Cell With Cell Division

8/14/2019 Cell With Cell Division

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Cellular Diversity

75-100 trillion cells in the adult body- @ 200 differenttypes of cells

Vary in size and shape related to their function

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The Typical Cell

Not all cells contain all of these organelles.


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Identify the 3 types of lipid molecules found in cellmembranes: glycolipids, cholesterol and phospholipids

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Membrane Proteins

Integral versus Peripheral Proteins


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Functions of Membrane ProteinsFormation of Channel

passageway to allowspecific substance to passthrough

Transporter Proteinsbind a specific substance,change their shape & move it across membrane

Receptor Proteinscellular recognition site --bind to substance

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Cell Identity Markerallow cell to recognizeother similar cells

Cell Adhesion (Linker)anchor proteins in cellmembrane or to othercells

allow cell movementcell shape & structure

Act as Enzymespeed up reactions

Functions of Membrane Proteins


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The TransmembraneElectrochemical Potential

Concentration gradientWhat other solutes aredistributed differentlyacross the cellmembrane?

(review the slide from theintro. presentation)

Electrical gradientWhich solute(s)contribute to the netnegative charge insidecells?

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Transport Across the PlasmaMembrane

Differentiate betweenactive and passivetransport.Do all transport proteinsrequire ATP to movesubstances?

Why do substancescross membranespassively, i.e. what isthe force that drivespassive transport?


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DiffusionCrystal of dye placed in acylinder of waterDescribe the net directionof the movement of dyemolecules. Explain Describe the movement of dye molecules in the thirdcylinder

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Factors That Affect the Rate of Diffusion Across Cell Membranes

Describe the properties of materials that will diffusethrough a cell membrane. What kinds of materials donot diffuse through cell membranes?


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Osmosis of Water Through a Membrane

Pure water in the left arm & a membrane impermeable to thesolute found in the right armNet movement of water is down the concentration gradientfor water, until equilibrium is reachedOsmotic pressure is equal to the hydrostatic pressurenecessary to stop the net movement of water molecules

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Effects of Tonicity on CellMembranes

Isotonic solutionwater concentration the same inside & outside of cell results in nonet movement of water across cell membrane

Hypotonic solutionhigher concentration of water outside of cell results in hemolysis

Hypertonic solutionlower concentration of water outside of cell causes crenation


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Diffusion Through MembraneChannels

Each membrane channelis specific for particularion (K + , Cl-, Na + or Ca +2 )Slower than diffusionthrough membrane, butstill 1million K + through achannel in one secondChannels may be openall the time, or gated(closed randomly or as directed)

How might channels be regulated? Name one stimulus to open .

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Facilitated Diffusion of GlucoseGlucose binds to transportproteinTransport protein changesshapeGlucose moves across cellmembrane (but only downthe concentration gradient)Kinase enzyme reducesglucose concentration inside

the cell by transformingglucose into glucose-6-phosphate

Are these GluT transporters always present in cell membranes?


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Glut 4 Transporter

The receptor for the hormone insulin is a complex proteinthat acts as a catalyst, causing fusion of Glut 4 transportervesicles with the surface membrane (a process similar toexocytosis).

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Primary Active TransportTransporter protein called a pumpworks against concentration gradientrequires 40% of cellular ATP

Na+ /K + ATPase pumpmost common example

all cells have 1000s of themmaintains low concentration of Na +and a high concentration of K + in the cytosoloperates continually

Maintenance of osmotic pressure across membrane

cells do not normally shrink or swell due to osmosis & osmoticpressuresodium continually pumped out as if sodium could not enter the cell(factor in osmotic pressure of extracellular fluid)K + inside the cell contributes to osmotic pressure of cytosol

What other solutes contribute to osmotic pressure inside cells?


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Na+/K+ Pump & ATP As Its Energy Source

1. Na+ binding

2. ATP split

4. K+ binding

6. K+ is pushed in3. Na+pushed out

5. Phosphate release

3 Na+ ions removed from cell as 2 K+ brought into cell.

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Antiporters and Symporters

(one in & one out) (both going in)


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Pinocytosis and Phagocytosis

Pseudopods extend toform phagosomeLysosome joins it forintracellular digestion

No pseudopods formNonselective drinking of extracellular fluid

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Cell Organelles

Nonmembranous organelles lack membranes & areindirect contact with cytoplasmMembranous organelles surrounded by one or two lipidbilayer membranes


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Cytoskeleton

Network of proteinfilaments throughout thecytosolFunctions:

cell support and shapeorganization of chemicalreactionscell & organelle movement

Examples?Continually reorganized

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The Cytoskeletonal FilamentsMicrofilaments

thinnest filaments (actin)locomotion & divisionsupport microvilli

Intermediate filamentsseveral different proteinsanchor organelles

Microtubules

large cylindrical structures(composed of tubulin)flagella, cilia andcentrosomes


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Ribosomal RNA Large + small subunitsmade in the nucleolusassembled in the cytoplasm

small subunits holdmRNA during proteinsynthesis

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Smooth & Rough Endoplasmic ReticulumRough ER iscovered with fixedribosomes. What are thepossible destinationsfor proteins madehere?

Smooth ER contains enzymes,and may storesome cellchemicals.


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Packaging by Golgi Complex

Proteins pass from rough ER togolgi complex in transport vesicles

Finished proteins exit golgicomplex as component of:

secretory (for exocytosis),membrane, orstorage (lysosome) vesicles

Proteins in vesicle membranesfuse with plasma membrane

(example?)

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LysosomesMembranous vesicles

formed in Golgi complexfilled with digestive enzymespumps in H+ ions until internalpH reaches 5.0

Functionsdigest foreign substancesautophagy

recycles own organelles

autolysislysosomal damage after death


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Organization of DNA in

Chromosomes

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Protein SynthesisInstructions for making specificproteins is found in the DNA (your genes)

transcribe that information onto amessenger RNA molecule

each sequence of 3 nucleotides in DNA is called base tripleteach base triplet is transcribed as 3 RNA nucleotides (codon)

translate the message into a sequence of amino acidsin order to build a protein molecule

each codon must be matched by an anticodon found on thetRNA carrying a specific amino acid


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1. Transcription takes placein the nucleus.

2. Translation tak place at ribosomes,either fixed or free.

escribe the roles of e 3 types of RNA volved in protein nthesis.

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Normal Cell DivisionMitosis (somatic cell division)

one parent cell gives rise to 2 identical daughtercells

mitosis is nuclear divisioncytokinesis is cytoplasmic division

occurs in billions of cells each dayneeded for tissue repair and growth

Meiosis (reproductive cell division)egg and sperm cell productionin testes and ovary only


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The Cell Cycle in Somatic CellsProcess where cell duplicates its contents & divides in two

23 homologous pairs of chromosomes must beduplicatedgenes must be passed on correctly to the nextgeneration of cells

Mitosis = Nuclear divisioncontinuous process divided into 4 stagesprophase, metaphase, anaphase & telophase

Cytokinesis = division of the cytoplasm

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Interphase Stage of Cell CycleDoubling of DNA and centrosomePhases of interphase stage -- G 1, S, and G 2

G1 = cytoplasmic increase (G 0 if never divides again)S = replication of chromosomesG2 = cytoplasmic growth


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Replication of ChromosomesDoubling of genetic materialduring interphase. (S phase)DNA molecules unzipMirror copy is formed alongeach old strand.Nitrogenous bases pick upcomplementary base2 complete identical DNA molecules formed

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Stages of Nuclear Division:MitosisProphaseMetaphase

AnaphaseTelophase


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Control of Cell DestinyCell destiny is either to remain alive & functioning, to grow & divide or to dieHomeostasis must maintain balance betweencell multiplication & cell deathThe protein cyclin builds up during interphaseand triggers mitosisProgrammed cell death (apoptosis) occurs if atriggering agent turns on suicide enzymes

that kills the cellNecrosis is cell death caused by injury orinfection

Cell With Cell Division

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