p. 66 © 2015 pearson education, inc.. figure 3-2 the plasma membrane. extracellular fluid cytoplasm...

p. 66

© 2015 Pearson Education, Inc.

Figure 3-2 The Plasma Membrane.

EXTRACELLULAR FLUID

CYTOPLASM

Glycolipidsof glycocalyx

Phospholipidbilayer

Integral proteinwith channel

Hydrophobictails

Integralglycoproteins

Plasmamembrane

Gatedchannel

CholesterolPeripheralproteins

Hydrophilicheads

Cytoskeleton(Microfilaments)= 2 nm

p. 68© 2015 Pearson Education, Inc.

p. 72


Figure 03-04a

p. 74


Figure 03-04b

p. 74


Figure 3-5a The Endoplasmic Reticulum.

Ribosomes

Cisternae

Nucleus

The three-dimensional relationships between the rough and smooth endoplasmic reticula are shown here.

a

p. 75


LE 3-6

Secretoryvesicles

Transportvesicles

Secretoryproduct

p. 76


LE 3-7a

Endoplasmicreticulum

Lysosomes

Golgi apparatusMaturingface

CYTOSOL

Formingface

Plasmamembrane

Secretoryvesicles

EXTRACELLULAR FLUID

Vesicleincorporation in plasma membrane

Transportvesicle

Membrane renewalvesicles


Figure 3-7 Protein Synthesis, Processing, and Packaging (Part 1 of 11).

p. 78


Figure 3-7 Protein Synthesis, Processing, and Packaging (Part 2 of 11).

p. 79


LE 3-8-1

Golgiapparatus

Autolysisliberatesdigestiveenzymes Primary lysosome

3

2

1

Reabsorption

Secondarylysosome

Endocytosis

Secondarylysosome

Reabsorption

Damaged organelle

Extracellularsolid or

fluid

Exocytosisejects residue

Exocytosisejects residue

p. 80


LE 3-9

Organic moleculesand O2

CO2

ATP

Outermembrane

CristaeMatrix

Inner membrane

Glycolysis

Enzymes

Enzymesand

coenzymesof cristae

Cytoplasmof cell Cristae Matrix

CO2

O2

ATPPyruvic acid

GlucoseCYTOPLASM

ADP +phosphateTCA

Cycle

MATRIX

MITOCHONDRION

H p. 81


Figure 3-10 The Nucleus

Nucleoplasm

Chromatin

Nucleolus

Nuclear envelope

Nuclear pore

Important nuclear structuresare shown here.

Nuclear pores

Nuclear pore

Perinuclear space

Nuclear envelope

A nuclear pore is a largeprotein complex that spansthe nuclear envelope.

Nucleus

Inner membrane ofnuclear envelope

Broken edge ofouter membrane

Outer membrane ofnuclear envelope

Nucleus

TEM 4800

Freeze fracture SEM 9240

This cell was frozen and then broken apart to make itsinternal structures visible. The technique, called freezefracture or freeze-etching, provides a unique perspectiveon the internal organization of cells. The nuclear envelopeand nuclear pores are visible. The fracturing process brokeaway part of the outer membrane of the nuclear envelope,and the cut edge of the nucleus can be seen.


p.82

LE 3-11Nucleus

Cell preparedfor division

Telomeres of sister chromatids

Visiblechromosome

KinetochoreCentromere

Supercoiledregion

Nondividingcell

Chromatin innucleus

DNAdouble

helixNucleosome

Histones

p. 83


LE 3-12-1DNA

Gene

Templatestrand

Promoter

Triplet 1

Triplet 2

Triplet 3

Triplet 4

1

2

3

4

4

3

1

2

Co

mp

lem

en

tary

trip

lets

Codingstrand

RNApolymerase

KEYUracil (RNA)Adenine

Guanine Thymine (DNA)

Cytosine

p. 85


LE 3-12-2

Codon1

RNAnucleotide



Cytosine

p. 85


LE 3-12-3

Codon1

Codon2

Codon 4(stop codon)

Codon3

mRNAstrand



Cytosine

p. 85


Figure 03-13-0

pp. 88 & 89


Figure 3-13 The Process of Translation (Part 1 of 5).

Adenine

KEY

Guanine

Cytosine

Uracil

mRNA

DNA

NUCLEUS

First amino acid(methionine)

Transfer RNA(tRNA)

Small ribosomalsubunit

tRNA bindingsites

Anticodon

Binding of Small RibosomalSubunit

Start codon mRNA strand

1

Translation begins when the mRNAstrand binds to a small ribosomalsubunit near its P site, one of threeadjacent tRNA binding sites. A tRNAthen binds to the P site and to thestart codon on the mRNA strand.Binding occurs between threenucleotides of the start codon and thethree complementary nucleotides in asegment of the tRNA strand known asthe anticodon.

p. 88



Largeribosomal

subunit

Formation of Functional Ribosome2

The small and large ribosomal subunits theninterlock around the mRNA strand, forming afunctional ribosome. The initiation complexis now complete and protein synthesis can proceed. The tRNA in the P site holds whatwill become the first amino acid of a peptidechain. The adjacent A site is where anadditional tRNA can bind to the mRNAstrand. More than 20 kinds of transfer RNAexist, each with a different nucleotideSequence in the anticodon. Each tRNAcarries an amino acid, and there is at leastone tRNA anticodon that corresponds toeach of the amino acids used in proteinsynthesis.

p. 88



Peptidebond

Formation of PeptideBond

3

When a complementary tRNA bindsto the A site, ribosomal enzymesremove the amino acid from thetRNA at the P site and attach it tothe amino acid delivered to the Asite by forming a peptide bond.

p. 89



Extension of Polypeptide4

The ribosome then moves onecodon farther along the mRNAstrand. The tRNA that was in the Psite (anticodon UAC) now enters theE site, from where it is released intothe cytoplasm. The released tRNAcan now bind another amino acid ofthe same type and repeat the cycle. p. 89



Largeribosomal

subunit

Completion ofPolypeptide

5

Termination occurs as a proteinreleasing factor, not a tRNAmolecule, recognizes the stopcodon. A ribosomal enzyme thenbreaks the bond between thepolypeptide and the tRNA in the Psite, releasing the polypeptide. Otherribosomal enzymes separatethe ribosomal subunits and freethe intact strand of mRNA.

Small ribosomalsubunit

Completedpolypeptide

Stopcodon

mRNA strand

p. 89


Figure 3-15 Diffusion across the Plasma Membrane.

Channelprotein

Plasma membrane

EXTRACELLULAR FLUIDLipid-soluble moleculesdiffuse through theplasma membrane

Large molecules that cannotdiffuse through lipids cannotcross the plasma membraneunless they are transportedby a carrier mechanism

Small water-solublemolecules and ionsdiffuse throughmembrane channels

CYTOPLASM

p. 91© 2015 Pearson Education, Inc.

http://www.youtube.com/watch?v=VVORi8Bqlss&feature=related

http://www.youtube.com/watch?v=VVORi8Bqlss&feature=related

Images from: http://www.phschool.com/science/biology_place/biocoach/biomembrane1/solutions.html

http://www.phschool.com/science/biology_place/biocoach/biomembrane1/solutions.html

Figure 3-17 Osmotic Flow across a Plasma Membrane

Solutemolecules

Watermolecules

In an isotonic saline solution, noosmotic flow occurs, and thesered blood cells appear normal.

SEM of normal RBCin an isotonic solution

SEM of RBC in ahypotonic solution

Immersion in a hypotonic salinesolution results in the osmoticflow of water into the cells. Theswelling may continue until theplasma membrane ruptures, orlyses.

SEM of crenated RBCsin a hypertonic solution

Exposure to a hypertonic solutionresults in the movement of waterout of the cell. The red blood cellsshrivel and become crenated.

© 2015 Pearson Education, Inc. p. 94

EXTRACELLULAR FLUIDGlucose moleculeattaches toreceptorsite

Receptorsite Carrier

protein

Change inshape of

carrier protein

Glucose released intocytoplasmCYTOPLASM

p. 95


Figure 3-18 Facilitated Diffusion.

EXTRACELLULAR FLUID

Sodium–potassiumexchange

pump

CYTOPLASM

3 Na+

ADPATP2 K+

p. 96


Figure 3-19 The Sodium–Potassium Exchange Pump.

EXTRACELLULAR FLUID

Glucose

CYTOPLASM 3 Na+

ADP ATP

2 K+

Na+

Na+–K+

pump

p. 97


Figure 3-20 Secondary Active Transport.

EXTRACELLULAR FLUIDLigands binding to receptors

CYTOPLASM

Ligandreceptors

Exocytosis

7

2

3

Coatedvesicle

Endocytosis

1

Ligands

4

Ligandsremoved

Primarylysosome

Secondarylysosome

6

5

p. 97


Figure 3-21 Receptor-Mediated Endocytosis.


Figure 3-22 Overview of Membrane Transport (Part 7 of 8).

Example:Cholesteroland iron ionsare transportedthis way.

Endocytosis Endocytosis is the packaging of extracellular materials into a vesicle for transport into the cell.

Extracellular fluid Target molecules

Receptorproteins Vesicle

containingtarget molecules

Cytoplasm

Pinosome

Pinocytic vesicleforming

Pseudopodiumextends to

surround object

Phagosome

Example:Once thevesicle is insidethe cytoplasm,water and smallmolecules enterthe cell acrossthe vesiclemembrane.

Example:Large particlesare broughtinto the cell bycytoplasmicextensions(calledpseudopodia)that engulf theparticle andpull it into thecell.

Cell

Cell

Receptor-MediatedEndocytosis

Pinocytosis Phagocytosis

In receptor-mediatedendocytosis, targetmolecules bind to receptor proteins onthe membrane surface, triggering vesicleformation.

Substances Involved: Targetmolecules called ligands

Factors Affecting Rate: Number ofreceptors on the plasma membrane andthe concentration of target molecules

Substances Involved: Extracellular fluid, with dissolvedmolecules such as nutrients

Substances Involved: Bacteria,viruses, cellular debris, and otherforeign material

Factors Affecting Rate: Stimulusand mechanism not understood

Factors Affecting Rate: Presenceof pathogens and cellular debris

In pinocytosis, vesicles form atthe plasma membrane and bringfluids and small molecules into thecell. This process is often called“cell drinking.”

In phagocytosis, vesicles form atthe plasma membrane to bring solidparticles into the cell. This process isoften called “cell eating.”

LE 3-22b

Secondarylysosome

Phagosomefuses witha lysosome

Lysosome

Phagosome

PhagocytosisBacterium

Pseudopodium

Golgiapparatus

Exocytosis



Figure 3-22 Overview of Membrane Transport (Part 8 of 8).

Example:Cellular wastes invesicles areejected from thecell.

ExocytosisMaterialejected

from cell

Cell

In exocytosis, intracellular vesiclesfuse with the plasmamembrane to releasefluids and/or solids fromthe cells.

Substances Involved: Fluid andcellular wastes; secretory productsfrom some cells

Factors Affecting Rate: Stimulusand mechanism incompletelyunderstood

Segment 2DNA nucleotide

Segment 1

DNA polymerase

DNA polymeraseAdenine

Guanine

Cytosine

Thymine

KEY

p. 102


Figure 3-23 DNA Replication.

Centrioles(two pairs)

Astral rays andspindle fibers

Chromosomewith two sister

chromatids

Chromosomalmicrotubules

Metaphaseplate

Daughterchromosomes

Cleavagefurrow

Daughtercells

Anaphase Telophase Cytokinesis

Anaphase (AN-a-f z; ana-, apart) begins when the centromere of each chromatidpair splits and thechromatids separate. The two daughterchromosomes are now pulled toward opposite ends of the cell along thechromosomalmicrotubules.

During telophase(T¯L- -f z; telo-,end), each new cellprepares to return to the interphase state. The nuclearmembranes re-form, the nuclei enlarge, and thechromosomesgradually uncoil.This stage marks the end of mitosis.

Cytokinesis is thedivision of thecytoplasm into twodaughter cells.Cytokinesis usually begins with the formation of a cleavage furrow andcontinuesthroughouttelophase. Thecompletion ofcytokinesis marksthe end of celldivision.

E aa o

MetaphaseLate prophaseEarly prophase

Prophase (PR¯ -f z;pro, before) beginswhen thechromosomes coil so tightly they become visible as single structures under a light microscope. Anarray of microtubules called spindle fibersextends between the centriole pairs.Smaller microtubules called astral rays radiate into the cytoplasm.

Metaphase(MET-a-f z; meta,after) begins as the chromatids move to a narrow central zone called themetaphase plate.Metaphase endswhen all thechromatids arealigned in the plane of the metaphase plate.

O a

o

oE

a

e

As a result of DNAreplication during the Sphase, two copies of each chromosome now exist. Each copy, called a chromatid (KRO-ma-tid), is connected to itsduplicate copy at a single point, the centomere (SEN-tr -m r).Kinetochores(ki-N¯-t -korz) are theprotein-bound area of the centromere; theyattach to spindle fibers forming chromosomalmicrotubules.

¯

© 2015 Pearson Education, Inc.pp. 104-105

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