Anatomy and Physiology and Pa Tho Physiology Answer Sheet

8/3/2019 Anatomy and Physiology and Pa Tho Physiology Answer Sheet

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B. Pharm (Phar 115, Pharm 115)

(Sem. 1) Theory Examination 2011-12

Anatomy and physiology and

pathophysiology1

Paper ID. 5026, 0517

SOLVED BY SANDEEP SACHAN

1. (i) Write the composition of Plasma membrane.Composition

Cell membranes contain a variety of biological molecules, notably lipids and proteins.

Material is incorporated into the membrane, or deleted from it, by a variety of mechanisms:

Fusion of intracellular vesicles with the membrane (exocytosis) not only excretes thecontents of the vesicle but also incorporates the vesicle membrane's components into thecell membrane. The membrane may form blebs around extracellular material that pinch

off to become vesicles (endocytosis).

If a membrane is continuous with a tubular structure made of membrane material,then material from the tube can be drawn into the membrane continuously.

Although the concentration of membrane components in the aqueous phase is low(stable membrane components have low solubility in water), there is an exchange of

molecules between the lipid and aqueous phases.

Lipids
http://en.wikipedia.org/wiki/Vesicle_(biology)http://en.wikipedia.org/wiki/Exocytosishttp://en.wikipedia.org/wiki/Endocytosishttp://en.wikipedia.org/wiki/Endocytosishttp://en.wikipedia.org/wiki/Exocytosishttp://en.wikipedia.org/wiki/Vesicle_(biology)


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glycolipids: phosphatidylcholine (PtdCho),phosphatidylethanolamine (PtdEtn), phosphatidylinositol(PtdIns), phosphatidylserine (PtdSer).

The cell membrane consists of three classes of amphipathic lipids: phospholipids, glycolipids,

and cholesterols. The amount of each depends upon the type of cell, but in the majority of

cases phospholipids are the most abundant.In RBC studies, 30% of the plasma membrane is

lipid.

The fatty chains in phospholipids and glycolipids usually contain an even number of carbon

atoms, typically between 16 and 20. The 16- and 18-carbon fatty acids are the most common.

Fatty acids may be saturated or unsaturated, with the configuration of the double bonds

nearly always cis. The length and the degree of unsaturation of fatty acid chains have a

profound effect on membrane fluidity as unsaturated lipids create a kink, preventing the fattyacids from packing together as tightly, thus decreasing the melting temperature (increasing

the fluidity) of the membrane. The ability of some organisms to regulate the fluidity of their

cell membranes by altering lipid composition is called homeoviscous adaptation.

The entire membrane is held together via non-covalent interaction of hydrophobic tails,

however the structure is quite fluid and not fixed rigidly in place. Under physiological

conditions phospholipid molecules in the cell membrane are in the liquid crystalline state. It

means the lipid molecules are free to diffuse and exhibit rapid lateral diffusion along the layer

in which they are present. However, the exchange of phospholipid molecules between

intracellular and extracellular leaflets of the bilayer is a very slow process. Lipid rafts andcaveolae are examples ofcholesterol-enriched microdomains in the cell membrane.
http://en.wikipedia.org/wiki/File:Membrane_lipids.pnghttp://en.wikipedia.org/wiki/Phosphatidylcholinehttp://en.wikipedia.org/wiki/Phosphatidylethanolaminehttp://en.wikipedia.org/wiki/Phosphatidylinositolhttp://en.wikipedia.org/wiki/Phosphatidylinositolhttp://en.wikipedia.org/wiki/Phosphatidylserinehttp://en.wikipedia.org/wiki/Phospholipidhttp://en.wikipedia.org/wiki/Glycolipidhttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Red_blood_cellhttp://en.wikipedia.org/wiki/Melting_temperaturehttp://en.wikipedia.org/wiki/Membrane_fluidityhttp://en.wikipedia.org/wiki/Membrane_fluidityhttp://en.wikipedia.org/wiki/Homeoviscous_adaptationhttp://en.wikipedia.org/wiki/Non-covalenthttp://en.wikipedia.org/wiki/Physiological_conditionhttp://en.wikipedia.org/wiki/Physiological_conditionhttp://en.wikipedia.org/wiki/Liquid_crystalhttp://en.wikipedia.org/wiki/Lipid_raftshttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Lipid_raftshttp://en.wikipedia.org/wiki/Liquid_crystalhttp://en.wikipedia.org/wiki/Physiological_conditionhttp://en.wikipedia.org/wiki/Physiological_conditionhttp://en.wikipedia.org/wiki/Non-covalenthttp://en.wikipedia.org/wiki/Homeoviscous_adaptationhttp://en.wikipedia.org/wiki/Membrane_fluidityhttp://en.wikipedia.org/wiki/Membrane_fluidityhttp://en.wikipedia.org/wiki/Melting_temperaturehttp://en.wikipedia.org/wiki/Red_blood_cellhttp://en.wikipedia.org/wiki/Cholesterolhttp://en.wikipedia.org/wiki/Glycolipidhttp://en.wikipedia.org/wiki/Phospholipidhttp://en.wikipedia.org/wiki/Phosphatidylserinehttp://en.wikipedia.org/wiki/Phosphatidylinositolhttp://en.wikipedia.org/wiki/Phosphatidylinositolhttp://en.wikipedia.org/wiki/Phosphatidylethanolaminehttp://en.wikipedia.org/wiki/Phosphatidylcholinehttp://en.wikipedia.org/wiki/File:Membrane_lipids.png


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In animal cells cholesterol is normally found dispersed in varying degrees throughout cell

membranes, in the irregular spaces between the hydrophobic tails of the membrane lipids,

where it confers a stiffening and strengthening effect on the membrane.

Phospholipids forming lipid vesicles

Lipid vesicles or lisosomes are circular pockets that are enclosed by a lipid bilayer. These

structures are used in laboratories to study the effects of chemicals in cells by delivering thesechemicals directly to the cell, as well as getting more insight into cell membrane

permeability. Lipid vesicles and liposomes are formed by first suspending a lipid in an

aqueous solution then agitating the mixture through sonication, resulting in a vesicle. By

measuring the rate of efflux from that of the inside of the vesicle to the ambient solution,

allows researcher to better understand membrane permeability. Vesicles can be formed with

molecules and ions inside the vesicle by forming the vesicle with the desired molecule or ion

present in the solution. Proteins can also be embedded into the membrane through

solubilizing the desired proteins in the presence of detergents and attaching them to the

phospholipids in which the liposome is formed. These provide researchers with a tool to

examine various membrane protein functions.

Carbohydrates

Plasma membranes also contain carbohydrates, predominantly glycoproteins, but with some

glycolipids (cerebrosides and gangliosides). For the most part, no glycosylation occurs on

membranes within the cell; rather generally glycosylation occurs on the extracellular surface

of the plasma membrane.

The glycocalyx is an important feature in all cells, especially epithelia with microvilli. Recent

data suggest the glycocalyx participates in cell adhesion, lymphocyte homing, and many

others.

The penultimate sugar is galactose and the terminal sugar is sialic acid, as the sugar backbone

is modified in the golgi apparatus. Sialic acid carries a negative charge, providing an externalbarrier to charged particles.

Proteins

Proteins within the membrane are key to the functioning of the overall membrane. These

proteins mainly transport chemicals and information across the membrane. Every membrane

has a varying degree of protein content. Proteins can be in the form of peripheral or integral.

Type Description Examples

Integral proteins

ortransmembrane

proteins

Span the membrane and have a

hydrophilic cytosolic domain, which interacts with

internal molecules, a hydrophobic membrane-spanning

domain that anchors it within the cell membrane, and a

hydrophilic extracellular domain that interacts with

external molecules. The hydrophobic domain consists of

one, multiple, or a combination of-helices and

sheet protein motifs.

Ion

channels,proton

pumps,G protein-

coupled receptor

Lipid anchored

proteins

Covalently bound to single or multiple lipid molecules;

hydrophobically insert into the cell membrane and

anchor the protein. The protein itself is not in contactwith the membrane.

G proteins
http://en.wikipedia.org/wiki/Carbohydrateshttp://en.wikipedia.org/wiki/Glycoproteinhttp://en.wikipedia.org/wiki/Cerebrosidehttp://en.wikipedia.org/wiki/Gangliosidehttp://en.wikipedia.org/wiki/Glycosylationhttp://en.wikipedia.org/wiki/Glycocalyxhttp://en.wikipedia.org/wiki/Epitheliumhttp://en.wikipedia.org/w/index.php?title=Lymphocyte_homing&action=edit&redlink=1http://en.wiktionary.org/wiki/Penultimatehttp://en.wikipedia.org/wiki/Galactosehttp://en.wikipedia.org/wiki/Sialic_acidhttp://en.wikipedia.org/wiki/Golgi_apparatushttp://en.wikipedia.org/wiki/Integral_proteinhttp://en.wikipedia.org/wiki/Cytosolhttp://en.wikipedia.org/wiki/Protein_domainshttp://en.wikipedia.org/wiki/Alpha_helixhttp://en.wikipedia.org/wiki/Alpha_helixhttp://en.wikipedia.org/wiki/Alpha_helixhttp://en.wikipedia.org/wiki/Beta_sheethttp://en.wikipedia.org/wiki/Beta_sheethttp://en.wikipedia.org/wiki/Beta_sheethttp://en.wikipedia.org/wiki/Structural_motifhttp://en.wikipedia.org/wiki/Proton_pumphttp://en.wikipedia.org/wiki/Proton_pumphttp://en.wikipedia.org/wiki/G_protein-coupled_receptorhttp://en.wikipedia.org/wiki/G_protein-coupled_receptorhttp://en.wikipedia.org/wiki/Lipid_anchored_proteinhttp://en.wikipedia.org/wiki/Lipid_anchored_proteinhttp://en.wikipedia.org/wiki/Lipid_anchored_proteinhttp://en.wikipedia.org/wiki/G_proteinhttp://en.wikipedia.org/wiki/G_proteinhttp://en.wikipedia.org/wiki/G_proteinhttp://en.wikipedia.org/wiki/Lipid_anchored_proteinhttp://en.wikipedia.org/wiki/Lipid_anchored_proteinhttp://en.wikipedia.org/wiki/G_protein-coupled_receptorhttp://en.wikipedia.org/wiki/G_protein-coupled_receptorhttp://en.wikipedia.org/wiki/Proton_pumphttp://en.wikipedia.org/wiki/Proton_pumphttp://en.wikipedia.org/wiki/Structural_motifhttp://en.wikipedia.org/wiki/Beta_sheethttp://en.wikipedia.org/wiki/Beta_sheethttp://en.wikipedia.org/wiki/Alpha_helixhttp://en.wikipedia.org/wiki/Protein_domainshttp://en.wikipedia.org/wiki/Cytosolhttp://en.wikipedia.org/wiki/Integral_proteinhttp://en.wikipedia.org/wiki/Golgi_apparatushttp://en.wikipedia.org/wiki/Sialic_acidhttp://en.wikipedia.org/wiki/Galactosehttp://en.wiktionary.org/wiki/Penultimatehttp://en.wikipedia.org/w/index.php?title=Lymphocyte_homing&action=edit&redlink=1http://en.wikipedia.org/wiki/Epitheliumhttp://en.wikipedia.org/wiki/Glycocalyxhttp://en.wikipedia.org/wiki/Glycosylationhttp://en.wikipedia.org/wiki/Gangliosidehttp://en.wikipedia.org/wiki/Cerebrosidehttp://en.wikipedia.org/wiki/Glycoproteinhttp://en.wikipedia.org/wiki/Carbohydrates


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Peripheral

proteins

Attached to integral membrane proteins, or associated

with peripheral regions of the lipid bilayer. These

proteins tend to have only temporary interactions with

biological membranes, and, once reacted the molecule,

dissociates to carry on its work in the cytoplasm.

Some

enzymes,some

hormones

The cell membrane plays host to a large amount of protein that is responsible for its various

activities. The amount of protein differs between species and according to function, however

the typical amount in a cell membrane is 50%. These proteins are undoubtedly important to a

cell: Approximately a third of the genes in yeast code specifically for them, and this number

is even higher in multicellular organisms. The cell membrane, being exposed to the outside

environment, is an important site of cell-cell communication. As such, a large variety of

protein receptors and identification proteins, such as antigens, are present on the surface of

the membrane. Functions of membrane proteins can also include cell-cell contact, surface

recognition, cytoskeleton contact, signaling, enzymatic activity, or transporting substances

across the membrane.Most membrane proteins must be inserted in some way into the membrane. For this to occur,

an N-terminus "signal sequence" of amino acids directs proteins to the endoplasmic

reticulum, which inserts the proteins into a lipid bilayer. Once inserted, the proteins are then

transported to their final destination in vesicles, where the vesicle fuses with the target

membrane.

1 (ii) Write the functional unit in a Golgi complex.

The Golgi apparatus (also known as the dictyosome or Golgi body) is an organelle in a cell.

The Golgi apparatus, and Golgi body are the same thing. "The Golgi body and its vesicles

function in the sorting, modifying, and packaging of macro-molecules that are secreted by the

cell or used within the cell for various functions."

1(iii) Write the name of Clotting factor III.

Tissue factor, also called platelet tissue factor, factor III, thrombokinase, or CD142 is

a protein present in subendothelial tissue, platelets, andleukocytes necessary for the initiation

ofthrombin formation from the zymogen prothrombin. An incorrect synonym

is thromboplastin. Historically, thromboplastin was a lab reagent, usually derived from

placental sources, used to assay prothrombin times (PT time). Thromboplastin, by itself,

could activate the extrinsic coagulation pathway.

Functions

Coagulation

TF is the cell surface receptor for the serine protease factor VIIa.

The best known function of tissue factor is its role in blood coagulation. The complex of TF

with factor VIIa catalyzes the conversion of the inactive protease factor X into the active

protease factor Xa.

Together with factor VIIa, tissue factor forms the tissue factor or extrinsic pathway of

coagulation. This is opposed to the intrinsic (amplification) pathway which involves both

activated factor IX and factor VIII. Both pathways lead to the activation offactor X (the

common pathway) which combines with activated factor V in the presence of calcium

and phospholipid to produce thrombin (thromboplastin activity).
http://en.wikipedia.org/wiki/Peripheral_proteinhttp://en.wikipedia.org/wiki/Peripheral_proteinhttp://en.wikipedia.org/wiki/Peripheral_proteinhttp://en.wikipedia.org/wiki/Peripheral_protein#Enzymeshttp://en.wikipedia.org/wiki/Peripheral_protein#Enzymeshttp://en.wikipedia.org/wiki/Peripheral_protein#Polypeptide_ligands_.28hormones.2C_inhibitors.2C_toxins.2C_antimicrobial_peptides.29http://en.wikipedia.org/wiki/Peripheral_protein#Polypeptide_ligands_.28hormones.2C_inhibitors.2C_toxins.2C_antimicrobial_peptides.29http://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Yeasthttp://en.wikipedia.org/wiki/Antigenhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Cluster_of_differentiationhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Endotheliumhttp://en.wikipedia.org/wiki/Plateletshttp://en.wikipedia.org/wiki/Leukocytehttp://en.wikipedia.org/wiki/Thrombinhttp://en.wikipedia.org/wiki/Prothrombinhttp://en.wikipedia.org/wiki/Serine_proteasehttp://en.wikipedia.org/wiki/Blood_coagulationhttp://en.wikipedia.org/wiki/Factor_VIIhttp://en.wikipedia.org/wiki/Factor_Xhttp://en.wikipedia.org/wiki/Factor_Xahttp://en.wikipedia.org/wiki/Factor_IXhttp://en.wikipedia.org/wiki/Factor_VIIIhttp://en.wikipedia.org/wiki/Factor_Xhttp://en.wikipedia.org/wiki/Factor_Vhttp://en.wikipedia.org/wiki/Phospholipidhttp://en.wikipedia.org/wiki/Thrombinhttp://en.wikipedia.org/wiki/Thrombinhttp://en.wikipedia.org/wiki/Phospholipidhttp://en.wikipedia.org/wiki/Factor_Vhttp://en.wikipedia.org/wiki/Factor_Xhttp://en.wikipedia.org/wiki/Factor_VIIIhttp://en.wikipedia.org/wiki/Factor_IXhttp://en.wikipedia.org/wiki/Factor_Xahttp://en.wikipedia.org/wiki/Factor_Xhttp://en.wikipedia.org/wiki/Factor_VIIhttp://en.wikipedia.org/wiki/Blood_coagulationhttp://en.wikipedia.org/wiki/Serine_proteasehttp://en.wikipedia.org/wiki/Prothrombinhttp://en.wikipedia.org/wiki/Thrombinhttp://en.wikipedia.org/wiki/Leukocytehttp://en.wikipedia.org/wiki/Plateletshttp://en.wikipedia.org/wiki/Endotheliumhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Cluster_of_differentiationhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Antigenhttp://en.wikipedia.org/wiki/Yeasthttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Peripheral_protein#Polypeptide_ligands_.28hormones.2C_inhibitors.2C_toxins.2C_antimicrobial_peptides.29http://en.wikipedia.org/wiki/Peripheral_protein#Polypeptide_ligands_.28hormones.2C_inhibitors.2C_toxins.2C_antimicrobial_peptides.29http://en.wikipedia.org/wiki/Peripheral_protein#Enzymeshttp://en.wikipedia.org/wiki/Peripheral_protein#Enzymeshttp://en.wikipedia.org/wiki/Peripheral_proteinhttp://en.wikipedia.org/wiki/Peripheral_protein


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CytokineTF is related to a protein family known as the cytokine receptor class II family. The members

of this receptor family are activated by cytokines. Cytokines are small proteins that can

influence the behavior ofwhite blood cells. Binding of VIIa to TF has also been found to start

signaling processes inside the cell. The signaling function of TF/VIIa plays a role

in angiogenesis and apoptosis.

1 (iv) Define the term Disease.

Disease

The term disease broadly refers to any condition that impairs normal function. Commonly,

this term is used to refer specifically to infectious diseases, which are clinically evident

diseases that result from the presence ofpathogenic microbial agents, including viruses,

bacteria, fungi, protozoa, multicellular organisms, and aberrant proteins known as prions.

An infection that does not and will not produce clinically evident impairment of normal

functioning, such as the presence of the normal bacteria and yeasts in the gut, is not

considered a disease; by contrast, an infection that is asymptomatic during its incubation

period, but expected to produce symptoms later, is usually considered a disease. Non-

infectious diseases are all other diseases, including most forms ofcancer,heart disease,

and genetic disease.

Death due to disease is called death by natural causes. There are four main types of disease:

pathogenic disease, deficiency disease, hereditary disease, and physiological disease.

Diseases can also be classified as communicable and non-communicable disease

1(v) Write another name of Folic acid.
http://en.wikipedia.org/wiki/Cytokineshttp://en.wikipedia.org/wiki/White_blood_cellhttp://en.wikipedia.org/wiki/Angiogenesishttp://en.wikipedia.org/wiki/Apoptosishttp://en.wikipedia.org/wiki/Infectious_diseasehttp://en.wikipedia.org/wiki/Pathogenichttp://en.wikipedia.org/wiki/Prionhttp://en.wikipedia.org/wiki/Infectionhttp://en.wikipedia.org/wiki/Gut_florahttp://en.wikipedia.org/wiki/Incubation_periodhttp://en.wikipedia.org/wiki/Incubation_periodhttp://en.wikipedia.org/wiki/Non-infectious_diseasehttp://en.wikipedia.org/wiki/Non-infectious_diseasehttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Heart_diseasehttp://en.wikipedia.org/wiki/Genetic_diseasehttp://en.wikipedia.org/wiki/Death_by_natural_causeshttp://en.wikipedia.org/wiki/Death_by_natural_causeshttp://en.wikipedia.org/wiki/Genetic_diseasehttp://en.wikipedia.org/wiki/Heart_diseasehttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Non-infectious_diseasehttp://en.wikipedia.org/wiki/Non-infectious_diseasehttp://en.wikipedia.org/wiki/Incubation_periodhttp://en.wikipedia.org/wiki/Incubation_periodhttp://en.wikipedia.org/wiki/Gut_florahttp://en.wikipedia.org/wiki/Infectionhttp://en.wikipedia.org/wiki/Prionhttp://en.wikipedia.org/wiki/Pathogenichttp://en.wikipedia.org/wiki/Infectious_diseasehttp://en.wikipedia.org/wiki/Apoptosishttp://en.wikipedia.org/wiki/Angiogenesishttp://en.wikipedia.org/wiki/White_blood_cellhttp://en.wikipedia.org/wiki/Cytokines


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Folic acid (also known as vitamin B9, vitamin Bc or folacin) and folate (the form naturally

occurring in the body), as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate,

and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9. Folic acid is itself

not biologically active, but its biological importance is due to tetrahydrofolate and other

derivatives after its conversion to dihydrofolic acid in the liver.Vitamin B9 (folic acid and

folate inclusive) is essential to numerous bodily functions. The human body needs folate tosynthesize DNA, repair DNA, and methylate DNA as well as to act as a cofactor in biological

reactions involving folate. It is especially important in aiding rapid cell division and growth,

such as in infancy and regnancy. Children and adults both require folic acid

to produce healthy red blood cells and prevent anemia.

1(vi) Define Fibrous joint.

Fibrous joints are connected by dense connective tissue, consisting mainly ofcollagen.

Types

These joints are also called "fixed" or "immoveable" joints, because they do not move. These

joints have no joint cavity and are connected via fibrous connective tissue. The skull bones

are connected by fibrous joints.

Sutures are found between bones of the skull. In fetal skulls the sutures are wide to allow

slight movement during birth. They later become rigid (synarthrodial).

Syndesmoses are found between long bones of the body, such as the radius and ulna in

forearm and the fibula and tibia in leg. Unlike other fibrous joints, syndesmoses are moveable

(amphiarthrodial), albeit not to such degree as synovial joints.

Gomphosis is a joint between the root of a tooth and the sockets in the maxilla or mandible.

1(vii) Write any two names of Protein deficiency disorders.

MARASMUS

Marasmus is a disease caused by a severe deficiency of protein and calories that affect infants

and very young children, often resulting in weight loss and dehydration. Marasmus can

develop into starvation and cause fatality caused by a lack of essential nutrients. People with

marasmus appear bony with little muscle tissue, according to Food4Africa.

KWASHIORKOR

Kwashiorkor is a disease caused by a severe deficiency of protein in diets that contain

calories mostly from carbohydrates such as yams, rice and bananas. It usually affects older

children. People with kwashiorkor appear puffy in the abdomen area from retention of fluid,

according to the University of Maryland Medical Center. Common symptoms of both

marasmus and kwashiorkor include fatigue, irritability, diarrhea, stunted growth andimpairment of cognition and mental health.

DEFICIENCIES OF PROTEIN C AND PROTEIN S

Deficiencies of protein C and protein S are inherited conditions that cause abnormal blood

clotting, according to Medline Plus. Deficiency of protein C occurs in about 1 out of 300

people. Deficiency of protein S affects 1 in 20,000 people. Symptoms for these deficiencies

include redness, pain, tenderness or swelling in the affected area. People with these protein

deficiencies need to be careful about activities that increase risk of blood clots, such as

prolonged sitting, bed rest, and long-time travel in cars and airplanes. Research by A. Hooda

published in the "Annals of Indian Academy of Neurology" in 2009 discovered that protein S

deficiency causes ischemic stroke.

CACHEXIA
http://en.wikipedia.org/wiki/Glutamic_acidhttp://en.wikipedia.org/wiki/Glutamatehttp://en.wikipedia.org/wiki/Chemical_formulahttp://en.wikipedia.org/wiki/Water-solublehttp://en.wikipedia.org/wiki/B_vitaminshttp://en.wikipedia.org/wiki/Tetrahydrofolatehttp://en.wikipedia.org/wiki/Dihydrofolic_acidhttp://en.wikipedia.org/wiki/Essential_nutrienthttp://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Cell_growthhttp://en.wikipedia.org/wiki/Childhttp://en.wikipedia.org/wiki/Adulthttp://en.wikipedia.org/wiki/Producehttp://en.wikipedia.org/wiki/Red_blood_cellhttp://en.wikipedia.org/wiki/Anemiahttp://en.wikipedia.org/wiki/Fibrous_connective_tissuehttp://en.wikipedia.org/wiki/Collagenhttp://en.wikipedia.org/wiki/Suture_(joint)http://en.wikipedia.org/wiki/Human_skullhttp://en.wikipedia.org/wiki/Synarthrodialhttp://en.wikipedia.org/wiki/Syndesmoseshttp://en.wikipedia.org/wiki/Radius_(bone)http://en.wikipedia.org/wiki/Ulnahttp://en.wikipedia.org/wiki/Fibulahttp://en.wikipedia.org/wiki/Tibiahttp://en.wikipedia.org/wiki/Amphiarthrodialhttp://en.wikipedia.org/wiki/Gomphosishttp://en.wikipedia.org/wiki/Toothhttp://en.wikipedia.org/wiki/Dental_alveolushttp://en.wikipedia.org/wiki/Maxillahttp://en.wikipedia.org/wiki/Human_mandiblehttp://en.wikipedia.org/wiki/Human_mandiblehttp://en.wikipedia.org/wiki/Maxillahttp://en.wikipedia.org/wiki/Dental_alveolushttp://en.wikipedia.org/wiki/Toothhttp://en.wikipedia.org/wiki/Gomphosishttp://en.wikipedia.org/wiki/Amphiarthrodialhttp://en.wikipedia.org/wiki/Tibiahttp://en.wikipedia.org/wiki/Fibulahttp://en.wikipedia.org/wiki/Ulnahttp://en.wikipedia.org/wiki/Radius_(bone)http://en.wikipedia.org/wiki/Syndesmoseshttp://en.wikipedia.org/wiki/Synarthrodialhttp://en.wikipedia.org/wiki/Human_skullhttp://en.wikipedia.org/wiki/Suture_(joint)http://en.wikipedia.org/wiki/Collagenhttp://en.wikipedia.org/wiki/Fibrous_connective_tissuehttp://en.wikipedia.org/wiki/Anemiahttp://en.wikipedia.org/wiki/Red_blood_cellhttp://en.wikipedia.org/wiki/Producehttp://en.wikipedia.org/wiki/Adulthttp://en.wikipedia.org/wiki/Childhttp://en.wikipedia.org/wiki/Cell_growthhttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Essential_nutrienthttp://en.wikipedia.org/wiki/Dihydrofolic_acidhttp://en.wikipedia.org/wiki/Tetrahydrofolatehttp://en.wikipedia.org/wiki/B_vitaminshttp://en.wikipedia.org/wiki/Water-solublehttp://en.wikipedia.org/wiki/Chemical_formulahttp://en.wikipedia.org/wiki/Glutamatehttp://en.wikipedia.org/wiki/Glutamic_acid


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Cachexia is a condition that involves protein deficiency, depletion of skeletal muscle and an

increased rate of protein degradation, Cachexia causes weight loss and mortality and is

associated with cancer, AIDS, chronic kidney failure, heat disease, chronic obstructive

pulmonary disease and rheumatoid arthritis, Patients with malignant cancer of the stomach,

colon, liver, billiary tract and pancreas experience under nutrition from reduced intake of

protein, calories and micronutrients, and have fatigue and a negative nitrogen balance as aresult of loss of muscle mass from cachexia

1(viii) Define the term Anatomy, Physiology and Cell biology.

Anatomy (from the Greek anatomia, from ana: separate, apart from, and temnein, to cut up,

cut open) is a branch ofbiology and medicine that is the consideration of the structure of

living things. It is a general term that includes human anatomy, animal anatomy (zootomy),

and plant anatomy (phytotomy). In some of its facets anatomy is closely related

to embryology, comparative anatomy and comparative embryology, through common roots

in evolution.

Anatomy is subdivided into gross anatomy (or macroscopic anatomy)

and microscopic anatomy. Gross anatomy is the study of anatomical structures that can, when

suitably presented or dissected, be seen by unaided vision with the naked eye. Microscopic

anatomy is the study of minute anatomical structures on a microscopic scale. It

includes histology (the study of tissues), and cytology (the study of cells). The terms

microanatomy and histology are also sometimes used synonymously (in which case the

distinction between histology and cell biology isn't strictly made as described here).

Physiology is the science of the function of living systems. This includes how organisms,

organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions

that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in

Physiology or Medicine, awarded since 1901 by the Royal Swedish Academy of Sciences.Many U.S. universities offer physiology as a major.

Human physiology is the science of the mechanical, physical, and biochemical functions of

humans in good health, their organs, and the cells of which they are composed. The principal

level of focus of physiology is at the level of organs and systems within systems. Much of the

foundation of knowledge in human physiology was provided by animal experimentation.

Physiology is closely related to anatomy; anatomy is the study of form, and physiology is the

study of function. Due to the frequent connection between form and function, physiology and

anatomy are intrinsically linked and are studied in tandem as part of a medical curriculum.

Cell biology (formerly cytology, from the Greekkytos, "contain") is a scientific

discipline that studies cellstheir physiological properties, their structure, the organelles theycontain, interactions with their environment, their life cycle, division and death. This is done

both on a microscopic and molecular level. Cellbiology research encompasses both the great

diversity of single-celled organisms like bacteria and protozoa, as well as the many

specialized cells in multicellular organisms such as humans.

Knowing the components of cells and how cells work is fundamental to all biological

sciences. Appreciating the similarities and differences between cell types is particularly

important to the fields of cell and molecular biology as well as to biomedical fields such

as cancer research and developmental biology. These fundamental similarities and

differences provide a unifying theme, sometimes allowing the principles learned from

studying one cell type to be extrapolated and generalized to other cell types. Therefore,

research in cell biology is closely related to genetics, biochemistry, molecular biology,immunology, and developmental biology.
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1(ix) Define Homeostasis.

Homeostasis (from Greek: hmoios, "similar"and stsis, "standing still") is the property of a

system that regulates its internal environment and tends to maintain a stable, constant

condition of properties like temperature or pH. It can be either an open or closed system.

Typically used to refer to a living organism, the concept came from that ofmilieu

interieur that was created by Claude Bernard and published in 1865. Multiple dynamic

equilibrium adjustment and regulation mechanisms make homeostasis possible.

1(x) Write the composition of milk.

The Milk Composition section describes the chemical and physical properties and effects of

pasteurization on the compounds in milk. A brief overview of the variation in milk

composition is provided below as an introduction to this section. Topics covered are:

Carbohydrate (Lactose)

Milk Carbohydrate (Lactose)

Milk contains approximately 4.9% carbohydrate that is predominately lactose with trace

amounts of monosaccharides and oligosaccharides. Lactose is a disaccharide of glucose andgalactose. The structure of lactose is:

Fat
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Milk Fat Chemistry

Milk contains approximately 3.4% total fat. Milk fat has the most complex fatty acid

composition of the edible fats. Over 400 individual fatty acids have been identified in milk

fat. However, approximately 15 to 20 fatty acids make up 90% of the milk fat. The majorfatty acids in milk fat are straight chain fatty acids that are saturated and have 4 to 18 carbons

(4:0, 6:0, 8:0, 10:0, 12:0, 14:0, 16:0, 18:0), monounsaturated fatty acids (16:1, 18:1), andpolyunsaturated fatty acids (18:2, 18:3). Some of the fatty acids are found in very small

amounts but contribute to the unique and desirable flavor of milk fat and butter. For example,

the C14:0 and C16:0 -hydroxy fatty acids spontaneously form lactones upon heating which

enhance the flavor of butter.

The fatty acid composition of milk fat is not constant throughout the cow's lactation cycle.

The fatty acids that are 4 to 14 carbons in length are made in the mammary gland of the

animal. Some of the 16 carbon fatty acids are made by the animal and some come from the

animal's diet. All of the 18 carbon fatty acids come from the animal's diet. There are

systematic changes in milk fat composition that are due to the stage of lactation and the

energy needs of the animal. In early lactation, the animal's energy comes largely from bodystores and there are limited fatty acids available for fat synthesis, so the fatty acids used for


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milk fat production are obtained from the diet and tend to be the longer chain 16:0, 18:0, 16:1

and 18:2 fatty acids. Later in lactation more of the fatty acids in milk are formed in the

mammary gland so that the concentration of the short chain fatty acids such as 4:0 and 6:0 are

higher than they are in early lactation. These changes in fatty acid composition do not have a

great impact on milk's nutritional properties, but may have some effect on processing

characteristics for products such as butter.

Milk fat contains approximately 65% saturated, 30% monounsaturated, and 5%

polyunsaturated fatty acids. From a nutritional perspective, not all fatty acids are created

equal. Saturated fatty acids are associated with high blood cholesterol and heart disease.

However, short chain fatty acids (4 to 8 carbons) are metabolized differently than long chain

fatty acids (16 to 18 carbons) and are not considered to be a factor in heart

disease.Conjugated linoleic acid is a trans fatty acid in milkfat that is beneficial to humans in

many ways. These issues are discussed in the Milk and Human Health section.

The fatty acids are arranged on the triglyceride molecule (Figure 1) in a specific manner.

Most of the short chain fatty acids are at the bottom carbon position of the triglyceridemolecule, and the longer fatty acids tend to be in the middle and top positions. The

distribution of the fatty acids on the triglyceride backbone affects the flavor, physical, and

nutritional properties of milk fat.

Protein

Milk Protein Chemistry

Milk contains 3.3% total protein. Milk proteins contain all 9 essential amino acids required

by humans. Milk proteins are synthesized in the mammary gland, but 60% of the amino acids

used to build the proteins are obtained from the cow's diet. Total milk protein content and

amino acid composition varies with cow breed and individual animal genetics.

There are 2 major categories of milk protein that are broadly defined by their chemical

composition and physical properties. The casein family contains phosphorus and will

coagulate or precipitate at pH 4.6. The serum (whey) proteins do not contain phosphorus, and

these proteins remain in solution in milk at pH 4.6. The principle of coagulation, or curd

formation, at reduced pH is the basis for cheese curd formation. In cow's milk, approximately82% of milk protein is casein and the remaining 18% is serum, or whey protein.
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The casein family of protein consists of several types of caseins (-s1, -s2 , , and 6) and

each has its own amino acid composition, genetic variations, and functional properties. The

caseins are suspended in milk in a complex called a micelle that is discussed below in

the physical properties section. The caseins have a relatively random, open structure due to

the amino acid composition (high proline content). The high phosphate content of the casein

family allows it to associate with calcium and form calcium phosphate salts. The abundanceof phosphate allows milk to contain much more calcium than would be possible if all the

calcium were dissolved in solution, thus casein proteins provide a good source of calcium for

milk consumers. The 6-casein is made of a carbohydrate portion attached to the protein chain

and is located near the outside surface of the casein micelle (see Figure 2 below). In cheese

manufacture, the 6-casein is cleaved between certain amino acids, and this results in a protein

fragment that does not contain the amino acid phenylalanine. This fragment is called milk

glycomacropeptide and is a unique source of protein for people with phenylketonuria.

The serum (whey) protein family consists of approximately 50% -lactoglobulin, 20% -

lactalbumin, blood serum albumin, immunoglobulins, lactoferrin, transferrin, and many

minor proteins and enzymes. Like the other major milk components, each whey protein hasits own characteristic composition and variations. Whey proteins do not contain phosphorus,

by definition, but do contain a large amount of sulfur-containing amino acids. These form

disulfide bonds within the protein causing the chain to form a compact spherical shape. The

disulfide bonds can be broken, leading to loss of compact structure, a process called

denaturing. Denaturation is an advantage in yogurt production because it increases the

amount of water that the proteins can bind, which improves the texture of yogurt. This

principle is also used to create specialized whey protein ingredients with unique functional

properties for use in foods. One example is the use of whey proteins to bind water in meat

and sausage products.

The functions of many whey proteins are not clearly defined, and they may not have a

specific function in milk but may be an artifact of milk synthesis. The function of -

lactoglobulin is thought to be a carrier of vitamin A. It is interesting to note that -

lactoglobulin is not present in human milk. -Lactalbumin plays a critical role in the

synthesis of lactose in the mammary gland. Immunoglobulins play a role in the animal's

immune system, but it is unknown if these functions are transferred to humans. Lactoferrin

and transferrin play an important role in iron absorption and there is interest in using bovine

milk as a commercial source of lactoferrin.
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Deterioration of Milk Protein

Proteins can be degraded by enzyme action or by exposure to light. The predominant cause of

protein degradation is through enzymes called proteases. Milk proteases come from several

sources: the native milk, airborne bacterial contamination, bacteria that are added

intentionally for fermentation, or somatic cells present in milk. The action of proteases can be

desirable, as in the case of yogurt and cheese manufacture, so, for these processes, bacteria

with desirable proteolytic properties are added to the milk. Undesirable degradation

(proteolysis) results in milk with off-flavors and poor quality. The most important protease in

milk for cheese manufacturing is plasmin because it causes proteolysis during ripening which

leads to desirable flavors and texture in cheese.

Two amino acids in milk, methionine and cystine are sensitive to light and may be degraded

with exposure to light. This results in an off-flavor in the milk and loss of nutritional quality

for these 2 amino acids.

Vitamins in Milk

Vitamins have many roles in the body, including metabolism co-factors, oxygen transport and

antioxidants. They help the body use carbohydrates, protein, and fat. The specific content of

vitamins in milk is listed in theNutrient Content Tables in the Nutrition Facts section.

Milk contains the water soluble vitamins thiamin (vitamin B1), riboflavin (vitamin B2),

niacin (vitamin B3), pantothenic acid (vitamin B5), vitamin B6 (pyridoxine), vitamin B12

(cobalamin), vitamin C, and folate. Milk is a good source of thiamin, riboflavin and vitamin

B12 . Milk contains small amounts of niacin, pantothenic acid, vitamin B6, vitamin C, and

folate and is not considered a major source of these vitamins in the diet.

Milk contains the fat soluble vitamins A, D, E, and K. The content level of fat soluble

vitamins in dairy products depends on the fat content of the product. Reduced fat (2% fat),

lowfat (1% fat), and skim milk must be fortified with vitamin A to be nutritionally equivalentto whole milk. Fortification of all milk with vitamin D is voluntary. Milk contains small
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amounts of vitamins E and K and is not considered a major source of these vitamins in the

diet.

Minerals in Milk

Minerals have many roles in the body including enzyme functions, bone formation, waterbalance maintenance, and oxygen transport. The specific content of minerals in milk is listed

in the Nutrient Content Tables in the Nutrition Facts section.

Milk is a good source of calcium, magnesium, phosphorus, potassium, selenium, and zinc.

Many minerals in milk are associated together in the form of salts, such as calcium

phosphate. In milk approximately 67% of the calcium, 35% of the magnesium, and 44% of

the phosphate are salts bound within the casein micelle and the remainder are soluble in the

serum phase. The fact that calcium and phosphate are associated as salts bound with the

protein does not affect the nutritional availability of either calcium or phosphate.

Milk contains small amounts of copper, iron, manganese, and sodium and is not considered amajor source of these minerals in the diet.

Effects of Heat Treatments & Light Exposure on the Vitamin & Mineral Content in

Milk

The mild heat treatment used in the typical high temperature short time

(HTST) pasteurization of fluid milk does not appreciably affect the vitamin content.

However, the higher heat treatment used in ultra high temperature (UHT) pasteurization for

extended shelf combined with the increased storage life of these products does cause losses of

some water-soluble vitamins. Thiamin is reduced from 0.45 to 0.42 mg/L, vitamin B 12 is

reduced from 3.0 to 2.7 g/L, and vitamin C is reduced from 2.0 to 1.8 mg/L (Potter et al.,

1984). Riboflavin is a heat stable vitamin and is not affected by severe heat treatments.

Calcium phosphate will migrate in and out of the casein micelle with changes in temperature.

This process is reversible at moderate temperatures. This does not affect the nutritional

properties of milk minerals. At very high temperatures the calcium phosphate may precipitate

out of solution which causes irreversible changes in the casein micelle structure.

Exposure to light will decrease the riboflavin and vitamin A content in milk. Milk should be

stored in containers that provide barriers to light (opaque plastic or paperboard) to maximize

vitamin retention.

Enzymes

Each enzyme has a specific site of action on its target molecule, and optimal conditions (pH

and temperature). There are a large number of enzymes in milk and the functions of many are

not well-defined. It should be noted that the enzymes in milk do not make a major

contribution to the digestion of milk in humans, which is accomplished by enzymes in the

human stomach and small intestine.

Lipases are enzymes that degrade fats. The major lipase in milk is lipoprotein lipase. It is

associated with the casein micelle. Agitation during processing may bring the lipase into
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contact with the milk fat resulting in fat degradation and off-flavors. Pasteurization will

inactivate the lipase in milk and increase shelf life.

Proteases are enzymes that degrade proteins. The major protease in milk is plasmin. Some

proteases are inactivated by heat and some are not. Protein degradation can be undesirable

and result in bitter off-flavors, or it may provide a desirable texture to cheese during ripening.Proteases are important in cheese manufacture, and a considerable amount of information is

available in the cheese literature.

Alkaline phosphatase is a heat sensitive enzyme in milk that is used as indicator

ofpasteurization. If milk is properly pasteurized, alkaline phosphatase is inactivated.

Lactoperoxidase is one of the most heat-stable enzymes found in milk. Lactoperoxidase,

when combined with hydrogen peroxide and thiocyanate, has antibacterial properties. It is

suggested that the presence of lactoperoxidase in raw milk inhibits the disease causing

microorganisms (pathogens) present in milk. However, since there is no hydrogen peroxide

or thiocyanate present in fresh milk, these compounds would have to be added to milk inorder to achieve the antibacterial benefits. Lysozyme is another enzyme that has some

antibacterial activities, although the amount of lysozyme present in milk is very small.

Unless otherwise stated, the information presented in this website refers to cow's milk.

In general, the gross composition of cow's milk in the U.S. is 87.7% water, 4.9% lactose

(carbohydrate), 3.4% fat, 3.3% protein, and 0.7% minerals (referred to as ash). Milk

composition varies depending on the species (cow, goat, sheep), breed (Holstein, Jersey), the

animal's feed, and the stage of lactation.

1(xi) Write the chief function of the serum albumin in the Blood.

Maintains osmotic pressure. Transports thyroid hormones. Transports other hormones, in particular, ones that are fat-soluble. Transports fatty acids ("free" fatty acids) to the liver. Transports unconjugated bilirubin. Transports many drugs; serum albumin levels can affect the half-life of drugs. Competitively binds calcium ions (Ca2+). Buffers pH. Serum albumin, as a negative acute-phase protein, is down-regulated in inflammatory

states. As such, it is not a valid marker of nutritional status; rather, it is a marker in

inflammatory states.

Prevents photo-degradation offolic acid.1(xii) Define Endocytosis.

Endocytosis is a process by which cells absorb molecules (such as proteins) by engulfing

them. It is used by all cells of the body because most substances important to them are

large polar molecules that cannot pass through the hydrophobic plasma or cell membrane.

The process which is the opposite to endocytosis is exocytosis.

1(xiii) Write the component of Nucleus.
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the nucleus (pl. nuclei;from Latin nucleus or nuculeus, meaning kernel) is a membrane-

enclosed organelle found ineukaryotic cells. It contains most of the cell's genetic material,

organized as multiple long linear DNA molecules in complex with a large variety ofproteins,

such as histones, to form chromosomes.

1(xiv) Give the function of golgi bodies.The Golgi apparatus (Golgi complex) is an organelle found in most eukaryotic cells. It was

identified in 1898 by the Italian physicianCamillo Golgi, after whom the Golgi apparatus is

named.

It processes and packages proteins inside of the cell and before they make their way to their

destination; it is particularly important in the processing of proteins for secretion. The Golgi

apparatus forms a part of the cellular endomembrane system.

Function

Cells synthesise a large number of different macromolecules. The Golgi apparatus is integral

in modifying, sorting, and packaging these macromolecules for cell secretion (exocytosis) oruse within the cell. It primarily modifies proteins delivered from the rough endoplasmic

reticulum but is also involved in the transport oflipids around the cell, and the creation

oflysosomes. In this respect it can be thought of as similar to a post office; it packages and

labels items which it then sends to different parts of the cell.

Enzymes within the cisternae are able to modify the proteins by addition of carbohydrates

(glycosylation) and phosphates (phosphorylation). In order to do so, the Golgi imports

substances such as nucleotide sugars from the cytosol. These modifications may also form

a signal sequence which determines the final destination of the protein. For example, the

Golgi apparatus adds a mannose-6-phosphate label to proteins destined for lysosomes.

The Golgi plays an important role in the synthesis ofproteoglycans, which are moleculespresent in the extracellular matrix of animals. It is also a major site ofcarbohydrate synthesis.

This includes the production ofglycosaminoglycans (GAGs), long unbranched

polysaccharides which the Golgi then attaches to a protein synthesised in the endoplasmic

reticulum to form proteoglycans. Enzymes in the Golgi polymerize several of these GAGs

via a xylose link onto the core protein. Another task of the Golgi involves the sulfation of

certain molecules passing through its lumen via sulfotranferases that gain their sulfur

molecule from a donor called PAPs. This process occurs on the GAGs of proteoglycans as

well as on the core protein. The level of sulfation is very important to the proteoglycans'

signalling abilities as well as giving the proteoglycan its overall negative charge.

The phosphorylation of molecules requires that ATP is imported into the lumen of the Golgi

and then utilised by resident kinases such as casein kinase 1 and casein kinase 2. One

molecule that is phosphorylated in the Golgi is Apolipoprotein, which forms a molecule

known as VLDL that is a constituent ofblood serum. It is thought that the phosphorylation of

these molecules is important to help aid in their sorting for secretion into the blood serum.

The Golgi has a putative role in apoptosis, with several Bcl-2 family members localised there,

as well as to the mitochondria. A newly characterized protein, GAAP (Golgi anti-apoptotic

protein), almost exclusively resides in the Golgi and protects cells from apoptosis by an as-

yet undefined mechanism.

1(xv) Define sickle cell anemia.

Sickle cell anemiaAnemia - sickle cell; Hemoglobin SS disease (Hb SS); Sickle cell disease
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Patients with sickle cell disease need ongoing treatment, even when they are not having a

painful crisis.

Folic acid supplements should be taken. Folic acid is needed to make red blood cells.

Treatment for a sickle cell crisis includes:

Blood transfusions (may also be given regularly to prevent stroke) Pain medicines Plenty of fluids

Other treatments for sickle cell anemia may include:

Hydroxyurea (Hydrea), a medicine that may help reduce the number of painepisodes (including chest pain and difficulty breathing) in some people

Antibiotics to prevent bacterial infections, which are common in children withsickle cell disease

Treatments for complications of sickle cell anemia may include:

Kidney dialysis or kidney transplant for kidney disease Drug rehabilitation and counseling for psychological complications Gallbladder removal in those with gallstone disease Hip replacement for avascular necrosis of the hip Treatments, including surgery, for persistent, painful erections (priapism) Surgery for eye problems Wound care, zinc oxide, or surgery for leg ulcers

Bone marrow or stem cell transplants can cure sickle cell anemia. However, they are current

not an option for most patients. Sickle cell anemia patients are often unable to find well-

matched donors.

1(xvi) Define the Coronal Plane and Sagital Plaine.

Sagittal plane is a vertical plane which passes from front to rear dividing the body into rightand left sections.

The terms median plane or mid-sagittal plane are sometimes used to describe the sagittal

plane running through the midline. This plane cuts the body into halves (assuming bilateral

symmetry),

passing through midline structures such as the navel and spine. It is one of the

lines defining the right upper quadrant of the human abdomen.

It is also worth mentioning that terms such as parasagittal are sometimes used to describe a

plane parallel to the midline; however, this term is unnecessary, since any plane parallel to

and on either side of the medial plane is sagittal by definition.
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In general, planes that are parallel to the sagittal plane, but do not pass through the midline,

are known as parasagittal.

The midclavicular line crosses through the clavicle.

Other sagittal lines/planes include the lateral sternal and parasternal.

A coronal plane (also known as the frontal plane) is any vertical plane that divides the body

into ventral and dorsal (belly and back) sections.

It is one of the planes of the body used to describe the location of body parts in relation to

each other.

SectionB2. Attempt any six question:(i) Describe the Structure and function of the mitochondria.

MitochondrionIn cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle

found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers (m) in

diameter. Mitochondria are sometimes described as "cellular power plants" because they

generate most of the cell's supply ofadenosine triphosphate (ATP), used as a source

ofchemical energy.In addition to supplying cellular energy, mitochondria are involved in a

range of other processes, such as signaling, cellular differentiation, cell death, as well as the

control of the cell cycle and cell growth.

Mitochondria have been implicated in several

human diseases, including mitochondrial disordersand cardiac dysfunction, and may play a

role in the aging process. The word mitochondrion comes from the Greek or mitos,

thread chondrion, granule.

Several characteristics make mitochondria unique. The number of mitochondria in a cell

varies widely by organism and tissue type. Many cells have only a single mitochondrion,

whereas others can contain several thousand mitochondria.The organelle is composed of

compartments that carry out specialized functions. These compartments or regions include

the outer membrane, the intermembrane space, the inner membrane, and

the cristae andmatrix. Mitochondrial proteins vary depending on the tissue and the species. In

humans, 615 distinct types of proteins have been identified from cardiacmitochondria,

whereas in Murinae (rats), 940 proteins encoded by distinct genes have been reported.The

mitochondrial proteome is thought to be dynamically regulated.

Although most of a cell's

DNA is contained in the cell nucleus, the mitochondrion has its own independent genome.

Further, its DNA shows substantial similarity to bacterial genomes.

Structure
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A mitochondrion contains outer and inner membranes composed ofphospholipid bilayers

and proteins. The two membranes, however, have different properties. Because of thisdouble- embraned organization, there are five distinct compartments within the

mitochondrion. There is the outer mitochondrial membrane, the intermembrane space (the

space between the outer and inner membranes), the inner mitochondrial membrane, the

cristae space (formed by infoldings of the inner membrane), and the matrix (space within the

inner membrane).

Outer membrane

The outer mitochondrial membrane, which encloses the entire organelle, has a protein-to-

phospholipid ratio similar to that of the eukaryotic plasma membrane (about 1:1 by weight).

It contains large numbers ofintegral proteins called porins. These porins form channels that

allow molecules 5000 Daltons or less in molecular weight to freely diffuse from one side ofthe membrane to the other.

Larger proteins can enter the mitochondrion if a signaling

sequence at their N-terminus binds to a large multisubunit protein called translocase of the

outer membrane, which then actively moves them across the membrane. Disruption of the

outer membrane permits proteins in the intermembrane space to leak into the cytosol, leading

to certain cell death.The mitochondrial outer membrane can associate with the endoplasmic

reticulum (ER) membrane, in a structure called MAM (mitochondria-associated ER-

membrane). This is important in ER-mitochondria calcium signaling and involved in the

transfer of lipids between the ER and mitochondria.

Inter membrane space

The intermembrane space is the space between the outer membrane and the inner membrane.Because the outer membrane is freely permeable to small molecules, the concentrations of

small molecules such as ions and sugars in the intermembrane space is the same as

the cytosol.

However, large proteins must have a specific signaling sequence to be

transported across the outer membrane, so the protein composition of this space is different

from the protein composition of the cytosol. One protein that is localized to the

intermembrane space in this way is cytochrome c

Inner membrane

The inner mitochondrial membrane contains proteins with five types of functions:

1. Those that perform the redox reactions ofoxidative phosphorylation2. ATP synthase, which generates ATP in the matrix
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3. Specific transport proteins that regulate metabolite passage into and out of the matrix4. Protein import machinery.5. Mitochondria fusion and fission protein

It contains more than 151 different polypeptides, and has a very high protein-to-phospholipid

ratio (more than 3:1 by weight, which is about 1 protein for 15 phospholipids). The inner

membrane is home to around 1/5 of the total protein in a mitochondrion. In addition, the inner

membrane is rich in an unusual phospholipid, cardiolipin. This phospholipid was originally

discovered in cow hearts in 1942, and is usually characteristic of mitochondrial and bacterial

plasma membranes. Cardiolipin contains four fatty acids rather than two, and may help to

make the inner membrane impermeable. Unlike the outer membrane, the inner membrane

doesn't contain porins, and is highly impermeable to all molecules. Almost all ions and

molecules require special membrane transporters to enter or exit the matrix. Proteins are

ferried into the matrix via the translocase of the inner membrane (TIM) complex or via Oxa1.

In addition, there is a membrane potential across the inner membrane, formed by the action

of the enzymes of the electron transport chain.

Cristae

Cross-sectional image of cristae in rat liver mitochondrion to demonstrate the likely 3D

structure and relationship to the inner membrane.

The inner mitochondrial membrane is compartmentalized into numerous cristae, which

expand the surface area of the inner mitochondrial membrane, enhancing its ability to

produce ATP. For typical liver mitochondria, the area of the inner membrane is about five

times greater than the outer membrane. This ratio is variable and mitochondria from cells that

have a greater demand for ATP, such as muscle cells, contain even more cristae. These folds

are studded with small round bodies known as F1 particles or oxysomes. These are not simple

random folds but rather invaginations of the inner membrane, which can affect

overall chemiosmotic function.

One recent mathematical modeling study has suggested that the optical properties of the

cristae in filamentous mitochondria may affect the generation and propagation of light within

the tissue.

Matrix

The matrix is the space enclosed by the inner membrane. It contains about 2/3 of the total

protein in a mitochondrion. The matrix is important in the production of ATP with the aid of

the ATP synthase contained in the inner membrane. The matrix contains a highly-

concentrated mixture of hundreds of enzymes, special mitochondrial ribosomes,tRNA, and

several copies of the mitochondrial DNA genome. Of the enzymes, the major functionsinclude oxidation ofpyruvate and fatty acids, and the citric acid cycle.

Mitochondria have their own genetic material, and the machinery to manufacture their

own RNAs and proteins (see: protein biosynthesis). A published human mitochondrial DNA

sequence revealed 16,569 base pairs encoding 37 total genes: 22 tRNA, 2 rRNA, and

13 peptide genes. The 13 mitochondrial peptides in humans are integrated into the inner

mitochondrial membrane, along withproteins encoded by genes that reside in the host

cell's nucleus.

Mitochondria-associated ER membrane (MAM)

The mitochondria-associated ER membrane (MAM) is another structural element that isincreasingly recognized for its critical role in cellular physiology and homeostasis. Once
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considered a technical snag in cell fractionation techniques, the alleged ER vesicle

contaminants that invariably appeared in the mitochondrial fraction have been re-identified as

membranous structures derived from the MAMthe interface between mitochondria and the

ER. Physical coupling between these two organelles had previously been observed in electron

micrographs and has more recently been probed with fluorescence microscopy.Such studies

estimate that at the MAM, which may comprise up to 20% of the mitochondrial outermembrane, the ER and mitochondria are separated by a mere 10-25 nm and held together by

protein tethering complexes.

Purified MAM from subcellular fractionation has shown to be enriched in enzymes involved

in phospholipid exchange, in addition to channels associated with Ca2+

signaling.These hints

of a prominent role for the MAM in the regulation of cellular lipid stores and signal

transduction have been borne out, with significant implications for mitochondrial-associated

cellular phenomena, as discussed below. Not only has the MAM provided insight into the

mechanistic basis underlying such physiological processes as intrinsic apoptosis and the

propagation of calcium signaling, but it also favors a more refined view of the mitochondria.

Though often seen as static, isolated powerhouses hijacked forcellular metabolism throughan ancient endosymbiotic event, the evolution of the MAM underscores the extent to which

mitochondria have been integrated into overall cellular physiology, with intimate physical

and functional coupling to the endomembrane system.

Phospholipid transfer

The MAM is enrichad in enzymes involved in lipid biosynthesis, such as phosphatidylserine

synthase on the ER face and phosphatidylserine decarboxylase on the mitochondrial face.

Because mitochondria are dynamic organelles constantly undergoing fission and fusion

events, they require a constant and well-regulated supply of phospholipids for membrane

integrity.

But mitochondria are not only a destination for the phospholipids they finish

synthesis of; rather, this organelle also plays a role in inter-organelle trafficking of theintermediates and products of phospholipid biosynthetic pathways, ceramide and cholesterol

metabolism, and glycosphingolipid anabolism.

Such trafficking capacity depends on the MAM, which has been shown to facilitate transfer

of lipid intermediates between organelles.In contrast to the standard vesicular mechanism of

lipid transfer, evidence indicates that the physical proximity of the ER and mitochondrial

membranes at the MAM allows for lipid flipping between apposed bilayers. Despite this

unusual and seemingly energetically unfavorable mechanism, such transport does not require

ATP. Instead, it has been shown to be dependent on a multiprotein tethering structure termed

the ER-mitochondria encounter structure, or ERMES, although it remains unclear whether

this structure directly mediates lipid transfer or is required to keep the membranes in

sufficiently close proximity to lower the energy barrier for lipid flipping.

The MAM may also be part of the secretory pathway, in addition to its role in intracellular

lipid trafficking. In particular, the MAM appears to be an intermediate destination between

the rough ER and the Golgi in the pathway that leads to very-low-density lipoprotein,

or VLDL, assembly and secretion. The MAM thus serves as a critical metabolic and

trafficking hub in lipid metabolism.

Calcium signaling

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