Figure 1-1 Levels of Organization Interacting atoms form molecules that combine in the protein...

Figure 1-1 Levels of Organization

Interacting atoms form molecules thatcombine in the protein filaments of a heartmuscle cell. Such cells interlock, creatingheart muscle tissue, which makes up most ofthe walls of the heart, a three-dimensionalorgan. The heart is only one component ofthe cardiovascular system, which alsoincludes the blood and blood vessels. Thevarious organ systems must work together tomaintain life at the organism level.

Integumentary

The Organ Systems

Skeletal

Atoms in combination

Muscular Nervous Cardiovascular

Complex protein moleculeProtein filaments

Chemical and Molecular Levels

Endocrine

Cellular Level

Heart musclecell

Major Organs• Skin• Hair• Sweat glands• Nails

Functions• Protects against environmental hazards• Helps regulate body temperature• Provides sensory information

Major Organs• Bones• Cartilages• Associated ligaments• Bone marrow

Functions• Provides support and protection for other tissues• Stores calcium and other minerals• Forms blood cells

Major Organs• Skeletal muscles and associated tendons

Major Organs• Brain• Spinal cord• Peripheral nerves• Sense organs

Major Organs• Pituitary gland• Thyroid gland• Pancreas• Adrenal glands• Gonads• Endocrine tissues in other systems

Functions• Provides movement• Provides protection and support for other tissues• Generates heat that maintains body temperature

Functions• Directs immediate responses to stimuli• Coordinates or moderates activities of other organ systems• Provides and interprets sensory information about external conditions

Functions• Directs long-term changes in the activities of other organ systems• Adjusts metabolic activity and energy use by the body* Controls many structural and functional changes during development

Functions• Distributes blood cells, water and dissolved materials including nutrients, waste products, oxygen, and carbon dioxide• Distributes heat and assists in control of body temperature

Major Organs• Heart• Blood• Blood vessels

Major Organs• Spleen• Thymus• Lymphatic vessels• Lymph nodes• Tonsils

Functions• Defends against infection and disease• Returns tissue fluids to the bloodstream

Major Organs• Nasal cavities• Sinuses• Larynx• Trachea• Bronchi• Lungs• Alveoli

Major Organs• Teeth• Tongue• Pharynx• Esophagus• Stomach• Small intestine• Large intestine• Liver• Gallbladder• Pancreas

Major Organs• Kidneys• Ureters• Urinary bladder• Urethra

Major Organs• Testes• Epididymides• Ductus deferentia• Seminal vesicles• Prostate gland• Penis• Scrotum

Major Organs• Ovaries• Uterine tubes• Uterus• Vagina• Labia• Clitoris• Mammary glands

Functions• Delivers air to alveoli (sites in lungs where gas exchange occurs)• Provides oxygen to bloodstream• Removes carbon dioxide from bloodstream• Produces sounds for communication

Functions• Processes and digests food• Absorbs and conserves water• Absorbs nutrients• Stores energy reserves

Functions• Produces male sex cells (sperm), suspending fluids, and hormones• Sexual intercourse

Functions• Excretes waste products from the blood• Controls water balance by regulating volume of urine produced• Stores urine prior to voluntary elimination• Regulates blood ion concentrations and pH

Functions• Produces female sex cells (oocytes) and hormones• Supports developing embryo from conception to delivery• Provides milk to nourish newborn infant• Sexual intercourse

Tissue LevelOrgan Level

Cardiac muscletissue

The heart

Organism level

Organ systemlevel

The cardiovascular

system

Lymphatic Respiratory Digestive Urinary Female ReproductiveMale Reproductive

© 2015 Pearson Education, Inc.pp. 8-9

Figure 1-1 Levels of Organization (Part 3 of 6)

Chemical and Molecular Levels

Cellular Level

Atoms in combination

Complex protein moleculeProtein filaments

Heart musclecell

© 2015 Pearson Education, Inc.p. 8


Tissue LevelOrgan Level

Cardiac muscletissue

The heart

Thecardiovascular

system

Organ systemlevel

Organismlevel


Figure 1-1 Levels of Organization (Part 5 of 6)The Organ Systems

Major Organs• Bones• Cartilages• Associated ligaments• Bone marrow

Skeletal CardiovascularEndocrineNervousMuscular

Major Organs• Skin• Hair• Sweat glands• Nails

Major Organs• Skeletal muscles and associated tendons

Major Organs• Pituitary gland• Thyroid gland• Pancreas• Adrenal glands• Gonads• Endocrine tissues in other systems

Major Organs• Brain• Spinal cord• Peripheral nerves• Sense organs

Functions• Protects support and protection for other tissues• Stores calcium and other minerals• Forms blood cells

Functions• Provides movement• Provides protection and support for other tissues• Generates heat that maintains body temperature

Functions• Directs immediate responses to stimuli• Coordinates or moderates activities of other organ systems• Provides and interprets sensory information about external conditions

Functions• Directs long-term changes in the activities of other organ systems• Adjusts metabolic activity and energy use by the body• Controls many structural and functional changes during development

Functions• Protects against environmental hazards• Helps regulate body temperature• Provides sensory information

Major Organs• Heart• Blood• Blood vessels

Functions• Distributes blood cells, water and dissolved materials including nutrients, waste products, oxygen, and carbon dioxide• Distributes heat and assists in control of body temperature

Integumentary



Major Organs• Spleen• Thymus• Lymphatic vessels• Lymph nodes• Tonsils

Functions• Defends against infection and disease• Returns tissue fluids to the bloodstream

Major Organs• Nasal cavities• Sinuses• Larynx• Trachea• Bronchi• Lungs• Alveoli

Major Organs• Teeth• Tongue• Pharynx• Esophagus• Stomach• Small intestine• Large intestine• Liver• Gallbladder• Pancreas

Major Organs• Kidneys• Ureters• Urinary bladder• Urethra

Major Organs• Testes• Epididymides• Ductus deferentia• Seminal vesicles• Prostate gland• Penis• Scrotum

Functions• Delivers air to alveoli (sites in lungs where gas exchange occurs)• Provides oxygen to bloodstream• Removes carbon dioxide from bloodstream• Produces sounds for communication

Functions• Processes and digests food• Absorbs and conserves water• Absorbs nutrients• Stores energy reserves

Functions• Produces male sex cells (sperm), suspending fluids, and hormones• Sexual intercourse

Functions• Excretes waste products from the blood• Controls water balance by regulating volume of urine produced• Stores urine prior to voluntary elimination• Regulates blood ion concentrations and pH

Functions• Produces female sex cells (oocytes) and hormones• Supports developing embryo from conception to delivery• Provides milk to nourish newborn infant• Sexual intercourse

Lymphatic Respiratory Digestive Female ReproductiveMale ReproductiveUrinary

Major Organs• Ovaries• Uterine tubes• Uterus• Vagina• Labia• Clitoris• Mammary glands

© 2015 Pearson Education, Inc. p. 9

Figure 1-5 Anatomical Landmarks

Cephalic or head

Frontal orforehead

Cranialor skull

Facialor face

Oral or mouthMental or chin

Axillary or armpit

Brachialor arm

Antecubitalor front of elbow

Antebrachialor forearm

Carpal or wrist

Palmar or palm

Pollexor thumb

Digits(phalanges)

or fingers (digitalor phalangeal)

Patellaror kneecap

Cruralor leg

Digits (phalanges)or toes (digital orphalangeal)

Tarsal orankle

Anterior view

Hallux orgreat toe

Pedalor foot

Femoralor thigh

Pubic(pubis)

Inguinalor groin

Manualor hand

Pelvic(pelvis)

Umbilicalor navel

TrunkAbdominal(abdomen)

Mammaryor breast

Thoracic orthorax, chest

Cervical or neck

Buccal or cheek

Otic or ear

Nasal or nose

Ocular, orbitalor eye

Posterior view

Acromial orshoulder

Olecranalor backof elbow

Lumbaror loin

Glutealor buttock

Popliteal orback of knee

Suralor calf

Calcaneal orheel of foot

Plantar orsole of foot

Dorsal orback

Upperlimb

Lower limb

Cervicalor neck

Cephalicor head


Figure 1-6 Abdominopelvic Quadrants and Regions

Abdominopelvic quadrants. The fourabdominopelvic quadrants are formed by twoperpendicular lines that intersect at the navel. Theterms for these quadrants, or their abbreviations, aremost often used in clinical discussions.

Right UpperQuadrant(RUQ)

Right LowerQuadrant(RLQ)

Left UpperQuadrant(LUQ)

Left LowerQuadrant(LLQ)

Righthypochondriacregion

Right lumbarregion

Rightinguinalregion

Abdominopelvic regions. The nine abdominopelvicregions provide more precise regional descriptions.

Left hypochondriacregion

Left lumbarregion

Left inguinalregion

Epigastricregion

Umbilicalregion

Hypogastric(pubic)region

Stomach

Spleen

Urinarybladder

Liver

Gallbladder

Large intestine

Small intestine

Appendix

Anatomical relationships. The relationship betweenthe abdominopelvic quadrants and regions and thelocations of the internal organs are shown here.


Figure 1-7 Directional References

Cranial

Posterioror dorsal

Anterioror ventral

Caudal

A lateral view.

Superior Right Left

Lateral

Proximal

Medial

Proximal

Distal

DistalInferiorAn anterior view. Arrowsindicate important directionalterms used in this text;definitions and descriptionsare given in Table 12.


Figure 1-8 Sectional Planes

Frontal plane

Transverse plane

Sagittal plane


Figure 1-10 The Ventral Body Cavity and Its Subdivisions

POSTERIOR ANTERIOR

Pleuralcavity

Pericardialcavity

Thoraciccavity

Pericardialcavity

Peritonealcavity

Abdominalcavity

Abdominopelviccavity

Spinal cord

Mediastinum

Parietalpleura

Pleural cavity

Pelviccavity

A lateral view showing the ventralbody cavity, which is divided by themuscular diaphragm into a superiorthoracic (chest) cavity and an inferiorabdominopelvic cavity. Three of thefour adult body cavities are shownand outlined in red; only one of thetwo pleural cavities can be shown in asagittal section.

A transverse section through the thoracic cavity, showing thecentral location of the pericardial cavity. Notice how themediastinum divides the thoracic cavity into two pleural cavities.Note that this transverse or cross-sectional view is oriented asthough the observer were standing at the subject’s feet andlooking toward the subject’s head. This is the standardpresentation for clinical images, and unless otherwise noted,sectional views in this text use this same orientation.

Rightlung

ANTERIOR

The heart projects into the pericardial cavity like a fistpushed into a balloon. The attachment site, corresponding tothe wrist of the hand, lies at the connection between theheart and major blood vessels. The width of the pericardialcavity is exaggerated here; normally the visceral and parietallayers are separated only by a thin layer of pericardial fluid.

Diaphragm

Heart

Visceralpericardium

Pericardialcavity

Parietalpericardium

Air space

Balloon

POSTERIOR

Leftlung


Figure 2-1 The Structure of Hydrogen Atoms

Electron shell

Hydrogen-1mass number: 1

A typical hydrogennucleus contains aproton and no neutrons.

Hydrogen-2,deuterium

A deuterium (2H)nucleus contains aproton and a neutron.

Hydrogen-3,tritium

A tritium (3H) nucleus contains a pair ofneutrons in additionto the proton.

mass number: 2 mass number: 3


Figure 2-2 The Arrangement of Electrons into Energy Levels

The first energy levelcan hold a maximum of

two electrons.

The second and thirdenergy levels can

each contain up to 8electrons.

Hydrogen, HAtomic number: 1Mass number: 1

1 electron

Lithium, LiAtomic number: 3Mass number: 6

(3 protons 3 neutrons)3 electrons

Hydrogen (H). A typicalhydrogen atom has oneproton and one electron.The electron orbiting thenucleus occupies the firstenergy level, diagrammedas an electron shell.

Helium (He). Anatom of helium hastwo protons, twoneutrons, and twoelectrons. The twoelectrons orbit in thesame energy level.

Neon, NeAtomic number: 10Mass number: 20


Lithium (Li). A lithiumatom has three protons,three neutrons, and threeelectrons. The first energylevel can hold only twoelectrons, so the thirdelectron occupies a second energy level.

Neon (Ne). A neonatom has 10 protons, 10neutrons, and 10electrons. The secondlevel can hold up toeight electrons; thus,both the first andsecond energy levelsare filled.

Helium, HeAtomic number: 2Mass number: 4



Figure 2-2a The Arrangement of Electrons into Energy Levels


two electrons.

Hydrogen, HAtomic number: 1Mass number: 1

1 electron

Hydrogen (H). A typicalhydrogen atom has oneproton and one electron.The electron orbiting thenucleus occupies the firstenergy level, diagrammedas an electron shell.© 2015 Pearson Education, Inc.

p. 30

Figure 2-2b The Arrangement of Electrons into Energy Levels


two electrons.

Helium (He). Anatom of helium hastwo protons, twoneutrons, and twoelectrons. The twoelectrons orbit in thesame energy level.

Helium, HeAtomic number: 2Mass number: 4



Figure 2-2c The Arrangement of Electrons into Energy LevelsThe second and

third energy levelscan each contain up

to 8 electrons.

Lithium, LiAtomic number: 3Mass number: 6


Lithium (Li). A lithiumatom has three protons,three neutrons, and threeelectrons. The first energy level can hold only two electrons, so the third electron occupies a second energy level.


Figure 2-2d The Arrangement of Electrons into Energy Levels

The second and third energy levelscan each containup to 8 electrons.

Neon, NeAtomic number: 10Mass number: 20


Neon (Ne). A neonatom has 10 protons,10 neutrons, and 10electrons. The secondlevel can hold up toeight electrons; thus,both the first andsecond energy levelsare filled.


Table 2-1 Principal Elements in the Human Body


Figure 2-5 Covalent Bonds in Five Common Molecules.

Molecule

Hydrogen(H2)

Oxygen(O2)

Carbondioxide(CO2)

Nitrogen(N2)

Nitricoxide(NO)

O O

H −H

O C

O

N ≡O

N O

Electron Shell Model andStructural Formula

p. 34

Figure 2-4 The Formation of Ionic Bonds

Formation of ions

Sodium atomSodium ion (Na)

Attraction betweenopposite charges

Formation of anionic compound

Sodium chloride (NaCl)

Chloride ion (Cl)Chlorine atom

Formation of an ionic bond. A sodium (Na) atom loses an electron,which is accepted by a chlorine (Cl) atom. Because the sodium (Na) .and chloride (Cl) ions have opposite charges, they are attracted to oneanother. The association of sodium and chloride ions forms the ioniccompound sodium chloride.

Chloride ions(Cl)

Sodium ions(Na)

Sodium chloridecrystal. Large numbersof sodium and chlorideions form a crystal ofsodium chloride (tablesalt).

3

21


Figure 2-4a The Formation of Ionic Bonds

Formation of ions

Sodium atomSodium ion (Na)

Attraction betweenopposite charges

Formation of anionic compound

Sodium chloride (NaCl)

Chloride ion (Cl)Chlorine atom

Formation of an ionic bond. A sodium (Na) atom loses an electron, which is accepted by a chlorine (Cl) atom. Because thesodium (Na) and chloride (Cl) ions have opposite charges, they areattracted to one another. The association of sodium and chlorideions forms the ionic compound sodium chloride.

1

3

2


Figure 2-4b The Formation of Ionic Bonds

Chloride ions(Cl)

Sodium ions(Na)

Sodium chloridecrystal. Largenumbers of sodium andchloride ions form acrystal of sodiumchloride (table salt).


http://web.virginia.edu/Heidi/chapter2/chp2.htm

Table 2-2 Important Electrolytes that Dissociate in Body Fluids


http://alevelnotes.com/Bonding/130

http://www.school-for-champions.com/chemistry/bonding_types.htm

http://www.tutorvista.com/content/chemistry/chemistry-i/chemical-bonding/triple-covalent-bond.php

http://www.school-for-champions.com/chemistry/bonding_types.htm

nonpolar: equal sharing of e-

Figure 2-6 Polar Covalent Bonds and the Structure of Water

Hydrogen atom

Hydrogen atom

Hydrogen atom

Oxygen atom

Oxygen atom

Formation of a watermolecule. In forming awater molecule, anoxygen atom completesits outermost energylevel by sharingelectrons with a pair ofhydrogen atoms. Thesharing is unequal,because the oxygenatom holds theelectrons more tightlythan do the hydrogenatoms.

Charges on a watermolecule. Because theoxygen atom has twoextra electrons much ofthe time, it develops a slight negative charge,and the hydrogenatoms become weaklypositive. The bonds in awater molecule arepolar covalent bonds.

2


http://www.elmhurst.edu/~chm/vchembook/162othermolecules.htmlhttp://www.dna-sequencing-service.com/dna-sequencing/dna-hydrogen-bonds-2/

© 2015 Pearson Education, Inc.

Figure 2-9a The Activities of Water Molecules in Aqueous Solutions

Negativepole

HPositive

pole

Water molecule. In awater molecule, oxygenforms polar covalentbonds with twohydrogen atoms.Because both hydrogenatoms are at one end ofthe molecule, it has anuneven distribution ofcharges, creating positive and negativepoles.


Figure 2-9b The Activities of Water Molecules in Aqueous Solutions

Cl

Na

Hydrationspheres

Sodium chloride insolution. Ionic compounds,such as sodium chloride,dissociate in water as thepolar water molecules breakthe ionic bonds in the largecrystal structure. Each ion insolution is surrounded bywater molecules, creatinghydration spheres.© 2015 Pearson Education, Inc.

p. 40

Figure 2-9c The Activities of Water Molecules in Aqueous Solutions

Glucose in solution.Hydration spheres alsoform around an organicmolecule containingpolar covalent bonds. Ifthe molecule bindswater strongly, as doesglucose, it will becarried into solution—inother words, it will dissolve. Note that themolecule does notdissociate, as occurs for ionic compounds.

Glucosemolecule


Figure 2-10 pH and Hydrogen Ion Concentration

1 mol/Lhydrochloric

acid

Stomachacid

Beer,vinegar,

wine,pickles

Tomatoes,grapes

Extremelyacidic

Increasing concentration of H Neutral Increasing concentration of OH Extremelybasic

Urine

Saliva,milk

Blood OceanwaterPure

waterEggs

Householdbleach Household

ammonia

Ovencleaner

1 mol/Lsodium

hydroxide

141312119 1010141013101210111010109

8108

7107

6106

5105

4104

3103

2102

1101

pH[H]

0100

(mol/L)


Figure 2-11a The Structure of Glucose

The structuralformula of thestraight-chain form


Figure 2-11b The Structure of Glucose

The structural formula ofthe ring form, the mostcommon form of glucose


Figure 2-12a The Formation and Breakdown of Complex Sugars

DEHYDRATION

SYNTHESIS

SucroseFructoseGlucose

Formation of the disaccharide sucrose through dehydration synthesis. Duringdehydration synthesis, two molecules are joined by the removal of a water molecule.


Figure 2-12a The Formation and Breakdown of Complex Sugars (Part 1 of 2)

DEHYDRATION

SYNTHESIS

FructoseGlucose

Formation of the disaccharide sucrose through

dehydration synthesis. During dehydration synthesis, two molecules are joined by the removal of a water molecule.


Figure 2-12a The Formation and Breakdown of Complex Sugars (Part 2 of 2)

DEHYDRATION

SYNTHESIS

Formation of the disaccharide sucrose through dehydration synthesis. During dehydration synthesis, two molecules are joined by the removal of a water molecule.

Sucrose


Figure 2-12b The Formation and Breakdown of Complex Sugars

HYDROLYSIS

GlucoseSucrose Fructose

Breakdown of sucrose into simple sugars by hydrolysis. Hydrolysis reverses the steps ofdehydration synthesis; a complex molecule is broken down by the addition of a water molecule.


Figure 2-12b The Formation and Breakdown of Complex Sugars (Part 1 of 2)

HYDROLYSIS

Sucrose

Breakdown of sucrose into simple sugars by hydrolysis. Hydrolysis reverses the steps of dehydration synthesis; a complex molecule is broken down by the addition of a water molecule.


Figure 2-12b The Formation and Breakdown of Complex Sugars (Part 2 of 2)

Breakdown of sucrose into simple sugars by hydrolysis. Hydrolysis reverses the steps of dehydration synthesis; a complex molecule is broken down by the addition of a water molecule.

HYDROLYSIS

Glucose Fructose


Table 2-4 Carbohydrates in the Body


Figure 2-13 The Structure of the Polysaccharide Glycogen

Glucosemolecules


Figure 2-16 Triglyceride Formation

Glycerol Fatty acids

Fatty Acid 2

Fatty Acid 1

Fatty Acid 3

Saturated

Saturated

Unsaturated

HYDROLYSISDEHYDRATIONSYNTHESIS

Triglyceride© 2015 Pearson Education, Inc.

p. 49

Figure 2-14a Fatty Acids

Lauric acid demonstrates two structuralcharacteristics common to all fatty acids: along chain of carbon atoms and a carboxylgroup (—COOH) at one end.

Lauric acid (C12H24O2)


Figure 2-14b Fatty Acids

Unsaturated

A fatty acid is either saturated (has singlecovalent bonds only) or unsaturated (hasone or more double covalent bonds). Thepresence of a double bond causes asharp bend in the molecule.

Saturated


Figure 2-18 Phospholipids and Glycolipids

The phospholipid lecithin. In a phospholipid, a phosphate grouplinks a nonlipid molecule to a diglyceride.

Glycerol

Carbohydrate

Phosphategroup

Fattyacids

In a glycolipid, a carbohydrateis attached to a diglyceride.

WATER

Nonlipid group

Fattyacids

Hydrophilicheads

Hydrophobictails

Phospholipid Glycolipid

In large numbers,phospholipids andglycolipids form micelles,with the hydrophilic headsfacing the water molecules,and the hydrophobic tailson the inside of eachdroplet.


Figure 2-15 Prostaglandins


Figure 2-19 Amino Acids

Structure of an Amino AcidAmino group

Central carbon

Carboxyl group

R group (variable side chainof one or more atoms)


Figure 2-20 The Fomation of Peptide Bonds

Peptide Bond Formation

Glycine (gly) Alanine (ala)

HYDROLYSISDEHYDRATION

SYNTHESIS

Peptide bond© 2015 Pearson Education, Inc.

p. 52

Figure 2-21 Protein Structure.

Linear chain of amino acids

Hydrogen bond

OR

A1 A2 A3 A4 A5 A6 A7 A8 A9

Primary structure. Theprimary structure of a polypep-tide is the sequence of aminoacids (A1, A2, A3, and so on)along its length.

Hydrogen bond

Alpha helix

A1 A3 A5 A7 A9

A2 A6

Secondary structure. Secondary structure is primarily the result of hydrogenbonding along the length of the polypeptide chain. Such bonding often produces asimple spiral, called an alpha helix (α helix) or a flattened arrangement known as abeta sheet (β sheet).

Tertiary structure. Tertiarystructure is the coiling and folding of a polypeptide. Within thecylindrical segments of thisglobular protein, the polypeptidechain is arranged in an alpha helix.

Alpha helix

Heme units

Hemoglobin(globular protein)

Quaternary structure. Quaternary structure develops when separatepolypeptide subunits interact to form a larger molecule. A singlehemoglobin molecule contains four globular subunits. Hemoglobintransports oxygen in the blood; the oxygen binds reversibly to the hemeunits. In collagen, three helical polypeptide subunits intertwine.Collagen is the principal extracellular protein in most organs.

Beta sheet

OR

Collagen(fibrous protein)

A1

A9

A11

A10

A3

A7

A13

A2

A8

A12

A4

A6

A14

A5

a

a

b

c

d

p. 53

Figure 2-21ab Protein Structure (Part 1 of 2).


A1 A2 A3 A4 A5 A6 A7 A8 A9

Primary structure. The pri-mary structure of a polypeptide is the sequence of amino acids (A1, A2, A3, and so on) along its length.

Hydrogen bond


Alpha helix

A1 A3 A5 A7 A9

A2 A6

a

b

p. 53

Figure 2-21ab Protein Structure (Part 2 of 2).


A1 A2 A3 A4 A5 A6 A7 A8 A9

Primary structure. The primary structure of a polypeptide is the sequence of amino acids (A1, A2, A3, and so on) along its length.

Hydrogen bond


Beta sheet

A1

A9

A11

A10

A3

A7

A13

A2

A8

A12

A4

A6

A14

A5

a

b

p. 53

Figure 2-21cd Protein Structure (Part 1 of 2).

Tertiary structure. Tertiarystructure is the coiling and folding of a polypeptide. Within thecylindrical segments of thisglobular protein, the polypeptidechain is arranged in an alpha helix.

Alpha helix

Heme units

Hemoglobin

(globular protein)

Quaternary structure. Quaternary structure develops when separatepolypeptide subunits interact to form a larger molecule. A singlehemoglobin molecule contains four globular subunits. Hemoglobintransports oxygen in the blood; the oxygen binds reversibly to the hemeunits. In collagen, three helical polypeptide subunits intertwine.Collagen is the principal extracellular protein in most organs.

c

d

p. 53

Figure 2-21cd Protein Structure (Part 2 of 2).

Tertiary structure. Tertiarystructure is the coiling and folding of a polypeptide. Within thecylindrical segments of this globular protein, the polypeptide chain is arranged in an alpha helix.

Alpha helix

Heme units

Quaternary structure. Quaternary structure develops when separate polypeptide subunits interact to form a larger molecule. A singlehemoglobin molecule contains four globular subunits. Hemoglobin transports oxygen in the blood; the oxygen binds reversibly to the hemeunits. In collagen, three helical polypeptide subunits intertwine. Collagen is the principal extracellular protein in most organs.

Collagen(fibrous protein)

c d

p. 53

Figure 2-22 A Simplified View of Enzyme Structure and Function

Substrates bind to activesite of enzyme

Once bound to theactive site, thesubstrates are heldtogether and theirinteraction facilitated

Substrate bindingalters the shapeof the enzyme, andthis change promotesproduct formation

Product detaches fromenzyme; entire process cannow be repeated

PRODUCT

PRODUCT

ENZYMEENZYME

S1S

2

Enzyme-substratecomplex

ENZYME

Activesite

Substrates

S1

S2

ENZYME


Figure 2-23 Nucleotides and Nitrogenous Bases

Generic nucleotideThe nitrogenous base may be a purine or a pyrimidine.

Sugar

Phosphategroup

Nitrogenousbase

Purines

Adenine

Guanine

Pyrimidines

Cytosine

Thymine(DNA only)

Uracil(RNA only)


Figure 2-24 The Structure of Nucleic Acids

Phosphategroup

Deoxyribose

Hydrogen bond

Adenine Thymine

DNA strand 1

DNA strand 2

RNA molecule. An RNAmolecule has a singlenucleotide chain. Its shapeis determined by thesequence ofnucleotides and bythe interactionsamong them.

DNA molecule. A DNAmolecule has a pair ofnucleotide chains linked byhydrogen bonding betweencomplementary base pairs.

Cytosine Guanine


Figure 2-24a The Structure of Nucleic Acids

RNA molecule. An RNAmolecule has a single nucleotide chain. Its shape is determined by the sequence of nucleotides and by the interactions among them.


Table 2-6 Comparison of RNA with DNA


Figure 2-25 The Structure of ATP

Adenine

Ribose Phosphate Phosphate Phosphate

High-energy bondsAdenosine

Adenosine monophosphate (AMP)

Adenosine diphosphate (ADP)

Adenosine triphosphate (ATP)

Adenine

Ribose

Adenosine

Phosphate groups

© 2015 Pearson Education, Inc.© 2015 Pearson Education, Inc.

p. 58

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