Cell Biology, Cytology

7/31/2019 Cell Biology, Cytology

1/64


2/64

Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Cytology, the study of the structure and function of cells

Cell biology

The human body contains both somatic and sex cells


3/64


THE CELL TYPES

Structural unit of living organism Two fundamentally different types

The prokaryotic cells --- only in bacteria

The eukaryotic cells


4/64

Cell Function Cells are the building blocks of all plants andanimals Cells are produced by the division of preexisting cells

Cells are the smallest units that perform all vitalphysiological functions Each cell maintains homeostasis at the cellularlevel

Homeostasis at higher levels reflects combined,coordinated action of many cells


5/64


CELLULAR FUNCTION

Movement Synthesis and secretion of enzymes Synthesis and secretion of mucous substances Synthesis and secretion of steroids Ion transport Intracellular digestion Metabolite absorption Transformation stimuli into nerve impulses


6/64

Cell Motility

The movement of whole cells is made possible throughthe membrane pliability and the rearrangement of thecytoskeleton and internal components


7/64

A Typical Cellfilaments)

2. Has organelles that perform specificfunctions in the cell (Mitochondria -

produces energy)3. Has certain active genes to give the cell a

specific function (heart cells, liver cells, brain cells, etc)

4. Has the information to perpetuate the whole organism as well as its specificfunction (Nucleus - DNA)


8/64Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Is surrounded by extracellular fluid, which is the

interstitial fluid of the tissue

A typical cell

Has an outer boundary called the cell membraneor plasma membrane



CELLULAR FLUID Human body ------60 % is fluid

Most of this fluid is inside the cells intracellular fluid extracellular fluid ---about one third

Consist of ions and nutrients The environment of the cells =internal

environment of the body = milieuinterieur



EXTRA AND INTRACELLULAR FLUID

Extra cellular Intracellular >> Na+ >> K+ Cl- Mg++ HCO3- Phosphates Nutrients



The Anatomy of a Representative Cell

Figure 3.2



THE CELL COMPONENTS

PLASMA MEMBRANE CYTOPLASM

Organelles : ribosome , endoplasmicreticulum, Golgi apparatus, lysosome,cytoskeleton ---embedded in thematrix ( cytosol )inclusion: carbohydrates, lipids andpigments

NUCLEUSNuclear envelope, DNA,chromosomes, chromatin andnucleolus



Nonmembranous organelles are not enclosed by a membrane and always in touch with the cytosol

Organelles

Cytoskeleton, microvilli, centrioles, cilia,ribosomes, proteasomes

Membranous organelles are surrounded by lipidmembranes

Endoplasmic reticulum, Golgi apparatus,lysosomes, peroxisomes, mitochondria


15/64

Different Types of Cell Movement (related tostructural components)Internal - movement of proteins, molecules,

organelles

External - movement of molecules into or out of the cellDetermined by cell membrane function and dynamics

Determined by cytoskeleton dynamics


16/64


PLASMA MEMBRANE

The outermost component of the cell Separates the cytoplasm from its

extracellular environment Contains protein called integrins


17/64


Membrane Structure

Primarily made up of lipids

Protein and carbohydrates

1. Lipids are the most abundantMembrane called phospholipid bilayer

Outermost portions - hydrophilic

Innermost layers - hydrophobic


18/64


Physical isolation

Cell membrane functions include:

Regulation of exchange with the environment

Changes in ECF, pH, receptorrecognition

Structural support


19/64


PLASMA MEMBRANE

FUNCTION Maintening the structural integrity of the cell Selective permeability Regulates the cell- cell interaction Recognition to antigen and foreign cells via

receptor Transducing extracellular signals into intra

cellular Acting as an interface between the cytoplasm

and the internal milieu


20/64


PLASMA MEMBRANE COMPOSITION PLASMA MEMBRANE COMPOSITION

PHOSPHOLIPID BILAYER : 1. POLAR HEAD (HYDROPHILIC HEAD) 2. NONPOLAR FATTY ACYL (HYDROPHOBIC )

PROTEIN MEMBRANE : 1. INTEGRAL PROTEIN

2. PERIPHERAL PROTEIN GLYCOCALYX : 1. GLYCOPROTEIN 2. GLYCOLIPID


21/64


Protein component

Integral proteins / transmembrane proteins : Directly incorporated within the lipid bilayer Can be extracted by drastic methods

Peripheral proteins : Exhibit a looser association with membrane surfaces Can be easily extracted with salt solutions


22/64


PROTEIN MEMBRANE INTEGRAL PROTEIN

EXSTRACELLULAR SURFACE RECEPTORS

CHANNEL PROTEIN CARRIER PROTEIN

PERIPHERAL PROTEIN CYTOPLASMA SURFACE

G- PROTEIN, ADENYL CYCLASE (AC),GUANYL CYCLASE (GC),

PHOSPHOLIPASE C (PLC)


23/64


The cell membrane is a phospholipid bilayer with

proteins, lipids and carbohydrates.

The Cell Membrane

Figure 3.3


24/64



25/64



26/64



27/64



28/64


P bilit


29/64


The ease with which substances can cross the cell membrane

Permeability

Nothing passes through an impermeable barrier Anything can pass through a freely permeable barrier

Cell membranes are selectively permeable

Selective permeability is based on size, electrical charges, molecularshape, and lipid solubility.

Transport of substances across the membrane can be Passive or ActiveActive transport requires energy to occur

Passive transport does not require energy

Diffusion, Osmosis and Active Transport are different types of movement


30/64


TRANSPORTATION VIA MEMBRANE

Passive without energy

Simple diffusion Fasilitated diffusion

Active with energy


31/64


MEMBRANE TRANSPORT PROTEINS

Channel Proteins:

Participate in formation of hydrophilic pores ion channels,across the plasmalemma

Gated or ungated Incapable of transporting substances against concentration

gradient

Carrier proteins : Can mediate such energy requiring active transport Multipass membrane transport proteins Possess binding sites for specific ions or molecules on

both sides Transport by carrier proteins can be passive or active Can be uniport or coupled ( symport and antiport )


32/64


Fi 3 19 Diff i h C ll M b


33/64


Figure 3.19 Diffusion across the Cell Membrane

Figure 3.19


34/64



35/64



36/64



37/64



38/64



39/64



40/64


Cytoskeleton provides strength flexibility and


41/64


Microfilaments(6nm) -

1. anchor cytockeleton to integral proteins,2. determine the consistency of the cytoplasm,3. interacts with myosin to produce movement

Cytoskeleton provides strength, flexibility andmotility

Intermediate filaments ( 7-11 nm)- Protein composition varies between cell types.1. Strengthen cell and help maintain shape;

2. Stabilize the position of organelles

3. Stabilize the position of the cell with respect to surrounding cells thru

specialized membrane attachments


42/64

Microtubules (up to 25nm)all cells contain microtubules, made up of protein tubulin. Largest cytoskeletal component

Functions:

1. Primary cytoskeletal component

2. Disassembly of microtubules provides a mechanism forchanging the shape of the cell and assisting in movement

3. Used to transport other proteins around the cell in associationwith motor proteins kinesin and dynein

4. Forms spindle apparatus during cell division

5. Form structural cell components such as cilia and centrioles

Figure 3 5 The Cytoskeleton


43/64


Figure 3.5 The Cytoskeleton

Figure 3.5

Figure 3 8 The Endoplasmic Reticulum


44/64


Figure 3.8 The Endoplasmic Reticulum

Figure 3.8

Site of protein and lipid synthesis

Figure 3 9 The Golgi Apparatus


45/64


Figure 3.9 The Golgi Apparatus

Figure 3.9

Forms secretory vesicles

Forms new membrane components

Figure 3 10 Functions of the Golgi Apparatus


46/64


Figure 3.10 Functions of the Golgi Apparatus

Figure 3.10

Lysosomes and Peroxisomes


47/64


Lysosomes are

Lysosomes and Peroxisomes

Filled with digestive enzymes

Responsible for autolysis of injured cells

Peroxisomes

Carry enzymes that neutralize toxins

Figure 3 11 Lysosome Functions


48/64


Figure 3.11 Lysosome Functions

Figure 3.11

Mitochondria


49/64


Responsible for ATP production through aerobicrespiration

Mitochondria

Matrix = fluid contents of mitochondria

Cristae = folds in inner membrane

The nucleus is the center of cellular operations


50/64


Surrounded by a nuclear envelope

The nucleus is the center of cellular operations

Perinuclear space

Communicates with cytoplasm throughnuclear pores

Figure 3 13 The Nucleus


51/64


Figure 3.13 The Nucleus

Figure 3.13

Contents of the nucleus


52/64


A supportive nuclear matrix

Contents of the nucleus

One or more nucleoli

Chromosomes

DNA bound to histones

Chromatin

Figure 3 14 Chromosome Structure


53/64


Figure 3.14 Chromosome Structure

Figure 3.14

The genetic code


54/64


The cells information storage system

The genetic code

Triplet code

A gene contains all the triplets needed to codefor a specific polypeptide

Gene activation and protein synthesis


55/64


Gene activation initiates with RNA polymerase binding to the gene

Gene activation and protein synthesis

Transcription is the formation of mRNA fromDNA

mRNA carries instructions from the nucleusto the cytoplasm


56/64


SECTION 3-6 The Cell Life Cycle

cell division


57/64


Cell division is the reproduction of cells

cell division

Apoptosis is the genetically controlled death of cells Mitosis is the nuclear division of somatic cells Meiosis produces sex cells

Interphase


58/64


Most somatic cells spend the majority of theirlives in this phase

Interphase

Interphase includes

G1 S

G2

Figure 3.27 The Cell Life Cycle


59/64


Figure 3.27 The Cell Life Cycle

Figure 3.27

Figure 3.28 DNA Replication


60/64


g p

Figure 3.28

Mitosis, or nuclear division, has four phases


61/64


Prophase

, , p

During cytokinesis, the cytoplasm divides andcell division ends

Metaphase

Anaphase

Telophase

Figure 3.29 Interphase, Mitosis, and Cytokinesis


62/64


g p , , y

Figure 3.29a-d

Figure 3.29 Interphase, Mitosis, and Cytokinesis


63/64


g p , , y

Figure 3.29e, f

Differentiation


64/64

Process of specialization

Results from inactivation of particular genes

Produces populations of cells with limitedcapabilities

Differentiated cells form tissues

Cell Biology, Cytology

Documents

Transcript of Cell Biology, Cytology