Cell Dr Ravish

7/31/2019 Cell Dr Ravish

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THE CELL

Cloned sheep (Dolly)


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Major Elements of the HumanBody

Carbon (C) Hydrogen (H) Oxygen (O)

Nitrogen (N)


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Lesser and Trace Elements of theHuman Body

Lesser elements make up 3.9% of thebody and include: Calcium (Ca), phosphorus (P), potassium (K),

sulfur (S), sodium (Na), chlorine (Cl),magnesium (Mg), iodine (I), and iron (Fe)

Trace elements make up less than 0.01%

of the body They are required in minute amounts, andare found as part of enzymes


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Cells: The Living Units

.
http://www.npl.co.uk/science-+-technology/biotechnology/dolly


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Cell Theory

The cell is the basic structural andfunctional unit of life (Schleiden & Schwann)

Organismal activity depends on individualand collective activity of cells

Biochemical activities of cells are dictated bysubcellular structure

Continuity of life has a cellular basis Virchow expanded on the cell theory and

concluded one living cell could only originatefrom another living cell


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Human cells are microscopic in

size , but they vary considerablyin size and differ even more inshape. For example : flat, brickshaped, threadlike, and irregularshapes.


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1 meter

10 -3

10 -6

10 -9

4.2 Most cells are microscopic, Cells vary in size and shape


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There are two kinds of cells Prokaryotic and Eukaryotic Common features of all cells are a plasma

membrane, DNA, and ribosomes.

4.3 Prokaryotic cells are structurally simpler than eukar yotic cells

Prokaryotic cell

Nucleoidregion

Nucleus

Eukar yotic cell Organelles

C o l o r i z e

d T E M

1 5

, 0 0 0

Figure 4.3A

The two groups (Domains) ofprokaryotic cells are the Bacteria and the Archaea .

Eukaryotic cells are usuallyrelatively larger (10 100 um ormore) in diameter. These cells areinternally complex, with organelles


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Composition of the CELL

Plasma membrane

Cytoplasma Organelles

Nucleus


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Part of the Cell

Plasma membrane: surrounds theentire cell, forming its outer

boundary Cytoplasma: living material insidethe cell (except the nucleus)

Nucleus: this structure containsthe genetic code


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Plasma membrane

It is the membrane that enclosesthe cytoplasm and form the outerboundary of the cell.

This membrane is compose by twolayers of phospolipids, also a fat

molecule called cholesterol (help tostabilize) and proteins (as receptor)


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Plasma Membrane

Figure 3.3


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Functions of Membrane Proteins

Transport Enzymatic activity Receptors for signal

transduction

Figure 3.4.1


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Functions of Membrane Proteins

Figure 3.4.2

Intercellularadhesion

Cell-cellrecognition

Attachment to

cytoskeleton andextracellular matrix


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Passive Membrane Transport:Diffusion

Simple diffusion nonpolar and lipid-soluble substances Diffuse directly through the lipid bilayer

Diffuse through channel proteins

Facilitated diffusion Transport of glucose, amino acids, and ions

Transported substances bind carrier proteinsor pass through protein channels


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Carriers

Are integral transmembrane proteins Show specificity for certain polar molecules

including sugars and amino acids


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Diffusion Through the PlasmaMembrane

Figure 3.7


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Effect of Membrane Permeability onDiffusion and Osmosis

Figure 3.8a


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Effects of Solutions of VaryingTonicity

Isotonic solutions with the same soluteconcentration as that of the cytosol

Hypertonic solutions having greater soluteconcentration than that of the cytosol

Hypotonic solutions having lesser soluteconcentration than that of the cytosol


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Active Transport

Uses ATP to move solutes across amembrane

Requires carrier proteins

Active TransportPLAY
http://../Anatomy%20Power%20Point/03PPTLect-anim/ActiveTransport.swfhttp://../Anatomy%20Power%20Point/03PPTLect-anim/ActiveTransport.swf


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Cytoplasma

It is the specialized living material of cells It lies between the plasma membrane and

the nucleus Numerous small structure (organelles) are

part of the cytoplasma, along with the fluidthat serves as the interiorenvironment of each cell


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Cytoplasmic Organelles

Specialized cellular compartments Membranous

Mitochondria, lysosomes, endoplasmicreticulum, and Golgi apparatus Nonmembranous

Cytoskeleton, centrioles, andribosomes


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Organelles

Ribosomes Endoplasmic reticulum

Golgi apparatus Mitocondria Lysosomes

Centrioles


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Isolating Organelles by CellFractionation

Cell fractionation takes cells apart and separatesthe major organelles from one another Ultracentrifuges fractionate cells into their

component parts Cell fractionation enables scientists to determine

the functions of organelles

LE 6-5a


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LE 6 5a

Homogenization

Homogenate Tissuecells

Differential centrifugation

LE 6-5b


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LE 6 5b

Pellet rich innuclei andcellular debris

Pellet rich inmitochondria(and chloro-plasts if cellsare from a plant)

Pellet rich inmicrosomes (pieces of plasmamembranes andcells internal membranes) Pellet rich in

ribosomes

150,000 g 3 hr

80,000 g 60 min

20,000 g 20 min

1000 g (1000 times theforce of gravity)

10 min

Supernatant pouredinto next tube


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CELL PART STRUCTURE FUNCTION(S)

PlasmaMembrane Phospholipid bilayerstudded with proteins Serves as the boundaryof the cell. P and C(outer surface) performvarious functions (Ex.markers and receptor)

Ribosomes Tiny particles eachmade up of rRNAsubunits

Synthesize proteins; acells protein factories

EndoplasmicReticulum(ER)

Membranous networkof interconnectedcanals and sacs, somewith ribosome (roughER) and some without(smooth ER)

Rough ER receives andtransports synthesizedproteinsSmooth ER synthesizes

lipids and carbohydrates


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Golgiapparatus

Stack of flattened,membranous sacs

Chemically processes,then packagessubstances from ER

Mitochondria Membranous capsulecontaining a large,folded membraneencrusted with

enzyme

ATP synthesis; a cellspowerhouse

Lysosomes Bubble of enzymesencased by membrane

A cells digestivesystem


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Nucleus Double-membraned,spherical envelopecontaining DNAstrands

Dictates proteinsynthesis, therebyplaying and essentialrole in other cellactivities, namely activetransport, metabolism,growth and heredity

Nucleolus Dense region of thenucleus

Plays an essential rolein the formation ofribosomes


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Mitochondria

Figure 3.17


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Mitochondria are the sites of cellular respiration Chloroplasts, found only in plants and algae, are

the sites of photosynthesis Mitochondria and chloroplasts are not part of the

endomembrane system Peroxisomes are oxidative organelles


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Mitochondria: Chemical EnergyConversion

Mitochondria are in nearly all eukaryotic cells They have a smooth outer membrane and an

inner membrane folded into cristae

The inner membrane creates two compartments:intermembrane space and mitochondrial matrix

Some metabolic steps of cellular respiration arecatalyzed in the mitochondrial matrix

Cristae present a large surface area for enzymesthat synthesize ATP

LE 6-17


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Mitochondrion

Intermembrane space

Outermembrane

Innermembrane

Cristae

Matrix

100 nm MitochondrialDNA

Freeribosomesin themitochondrialmatrix


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Endoplasmic Reticulum (ER)

Figure 3.18a and c


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The Endoplasmic Reticulum:Biosynthetic Factory

The endoplasmic reticulum (ER) accounts formore than half of the total membrane in manyeukaryotic cells

The ER membrane is continuous with the nuclearenvelope

There are two distinct regions of ER: Smooth ER, which lacks ribosomes

Rough ER, with ribosomes studding its surface

LE 6-12S th ER


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Ribosomes

Smooth ER

Rough ER

ER lumen Cisternae

Transport vesicle

Smooth ER Rough ER

Transitional ER 200 nm

Nuclearenvelope


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Functions of Smooth ER

The smooth ER Synthesizes lipids Metabolizes carbohydrates

Stores calcium Detoxifies poison


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Functions of Rough ER

The rough ER Has bound ribosomes Produces proteins and membranes, which are

distributed by transport vesicles Is a membrane factory for the cell

G l i A


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Golgi Apparatus

Figure 3.20a


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The Golgi apparatus consists of flattenedmembranous sacs called cisternae

Functions of the Golgiapparatus:

Modifies products of the ERManufactures certain macromoleculesSorts and packages materials into

transport vesicles


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Lysosomes: DigestiveCompartments

A lysosome is a membranous sac of hydrolyticenzymes

Lysosomal enzymes can hydrolyze proteins, fats,

polysaccharides, and nucleic acids Lysosomes also use enzymes to recycle

organelles and macromolecules, a process calledautophagy

Animation: Lysosome Formation

LE 6-14a1 mN l
http://media/06_14LysosomeFormation_A.htmlhttp://media/06_14LysosomeFormation_A.html


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Phagocytosis: lysosome digesting food

1 m

Plasmamembrane

Food vacuole

Lysosome

Nucleus

Digestiveenzymes

Digestion Lysosome

Lysosome containsactive hydrolyticenzymes

Food vacuolefuses withlysosome

Hydrolyticenzymes digestfood particles

LE 6-14bLysosome containing


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Autophagy: lysosome breaking downdamaged organelle

1 m

Vesicle containingdamaged mitochondrion

Mitochondrionfragment

Lysosome containingtwo damaged organelles

Digestion

Lysosome

Lysosome fuses withvesicle containingdamaged organelle

Peroxisomefragment

Hydrolytic enzymesdigest organellecomponents

N l


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Nucleus

Contains nuclear envelope, nucleoli,chromatin, and distinct compartments rich inspecific protein sets

Gene-containing control center of the cell Contains the genetic library with blueprints

for nearly all cellular proteins Dictates the kinds and amounts of proteins

to be synthesized

N l li


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Nucleoli

Dark-staining spherical bodies within thenucleus

Site of ribosome production

N l


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Nucleus

Figure 3.28a

THE CYTOSKELETON AND RELATED STRUCTURES


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Microfilaments of actin Enable cells to change shape and move

Intermediate filaments Reinforce the cell and anchor cer tain organelles

Microtubules give the cell rigidity

And provide anchors for organelles and act as tracksfor organelle movement

Actin subunit

Microfilament

7 nm

Fibrous subunits

10 nm

Intermediate filament Microtubule

25 nm

Tubulin subunit

THE CYTOSKELETON AND RELATED STRUCTURES

FUNCTIONAL CATEGORIES OF ORGANELLES


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FUNCTIONAL CATEGORIES OF ORGANELLES

4.19 Eukaryotic organelles comprise fourfunctional categories

Eukar

yotic organelles fall into four functionalgroups Manufacture : synthesis of macromolecules and

transport within the cell. Breakdown : elimination and recycling of cellular

materials. Energy processing : conversion of energy from one

form to another. Support, movement, and communication :

maintenance of cell shape, anchorage andmovement of organelles, and relationships with

extracellular environments All four categories work together as anintegrated team, producing the emergentproperties at the cellular level.


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THE END


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Cell Dr Ravish