Slide 1 Chapter 12: The Cell Cycle. Slide 2 Fig. 12-1 The Cell Cycle

Slide 1

Chapter 12:Chapter 12:

The Cell CycleThe Cell Cycle

Slide 2Fig. 12-1

The Cell CycleThe Cell Cycle

Figure 12.2

(a) Reproduction

(b) Growth and development

(c) Tissue renewal20 m

100 m

200 m

Why do Why do cells cells

divide?divide?

Figure 12.3

20 m

Eukaryotes Have ChromosomesEukaryotes Have Chromosomes

Figure 12.4

0.5 mCentromere

Sisterchromatids

Chromosomes are duplicated Chromosomes are duplicated before cell division!before cell division!

Figure 12.5-1

ChromosomesChromosomal

DNA molecules

Centromere

Chromosomearm

1

Figure 12.5-2

ChromosomesChromosomal

DNA molecules

Centromere

Chromosomearm

Chromosome duplication(including DNA replication)

and condensation

Sisterchromatids

1

2

Figure 12.5-3

ChromosomesChromosomal

DNA molecules

Centromere

Chromosomearm

Chromosome duplication(including DNA replication)

and condensation

Sisterchromatids

Separation of sisterchromatids into

two chromosomes

1

2

3

Slide 9

Chromosome arrangementChromosome arrangement

• Somatic cells – typical body cells Somatic cells – typical body cells

• 46 chromosomes in 23 pairs (humans)46 chromosomes in 23 pairs (humans)

• The chromosomes are not normally The chromosomes are not normally paired uppaired up

• Each pair is called homologous Each pair is called homologous chromosomeschromosomes

• Gametes – sex cellsGametes – sex cells

• 23 chromosomes (humans)23 chromosomes (humans)

• One member from each pairOne member from each pair

Slide 10

Homologous chromosomesHomologous chromosomes

• 22 of the pairs (autosomes) are “true 22 of the pairs (autosomes) are “true homologues”homologues”

• One of each came from mom and dadOne of each came from mom and dad

• Identical in length and type of genes carriedIdentical in length and type of genes carried

• Genes on each are slightly differentGenes on each are slightly different

• Sex chromosomes (23rd pair) don’t match Sex chromosomes (23rd pair) don’t match up exactly (X vs Y)up exactly (X vs Y)

Figure 13.3b

Pair of homologousduplicated chromosomes

Centromere

Sisterchromatids

Metaphasechromosome

5 m

Figure 12.6

INTERPHASE

G1

G2

S(DNA synthesis)

MITOTIC(M) PHASE

Cytokinesis

Mito

sis

The Cell CycleThe Cell Cycle

Slide 13

MitosisMitosis

• Division of the nucleusDivision of the nucleus

• Results in two nuclei that have the same Results in two nuclei that have the same chromosome number as the parentchromosome number as the parent

• The two nuclei are genetically identicalThe two nuclei are genetically identical

Slide 14

MitosisMitosis• Divided into 5 phases:Divided into 5 phases:

1.1. ProphaseProphase

2.2. PrometaphasePrometaphase

3.3. MetaphaseMetaphase

4.4. AnaphaseAnaphase

5.5. TelophaseTelophase

• Phases are determined by chromosome Phases are determined by chromosome movementmovement

• Chromosome movement determined by Chromosome movement determined by mitotic spindlemitotic spindle

• Mitotic spindle controlled by centrosomeMitotic spindle controlled by centrosome

Figure 12.8

Sisterchromatids

AsterCentrosome

Metaphaseplate

(imaginary)

Kineto-chores

Overlappingnonkinetochore

microtubules Kinetochoremicrotubules

Microtubules

Chromosomes

Centrosome

0.5 m

1 m

The Mitotic SpindleThe Mitotic Spindle

Figure 12.7a

G2 of Interphase Prophase Prometaphase

Centrosomes(with centriole

pairs)Chromatin

(duplicated)

NucleolusNuclear

envelope

Plasmamembrane

Early mitoticspindle

Aster

Centromere

Chromosome, consistingof two sister chromatids

Fragments of nuclearenvelope

Nonkinetochoremicrotubules

Kinetochore Kinetochoremicrotubule

Figure 12.7b

Metaphase

Metaphase plate

Anaphase Telophase and Cytokinesis

Spindle Centrosome atone spindle pole

Daughterchromosomes

Cleavagefurrow

Nucleolusforming

Nuclearenvelopeforming

Figure 12.7c

G2 of Interphase Prophase Prometaphase

10

m

Figure 12.7d

10

m

Metaphase Anaphase Telophase and Cytokinesis

Figure 12.11

ChromatincondensingNucleus

Nucleolus Chromosomes Cell plate10 m

Prophase Prometaphase Metaphase Anaphase Telophase1 2 3 4 5

Mitosis in a Plant CellMitosis in a Plant Cell

Figure 12.10

(a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (TEM)

Cleavage furrow

Contractile ring ofmicrofilaments

Daughter cells

Vesiclesformingcell plate

Wall of parent cell

Cell plate New cell wall

Daughter cells

100 m

1 m

Cytokenesis: Animal vs. Plant CellCytokenesis: Animal vs. Plant Cell

Figure 12.11

Binary Fission: Cell division in Binary Fission: Cell division in bacteriabacteria

Figure 12.12-1

1

Origin ofreplication

E. coli cell

Two copies of origin

Cell wall

Plasma membrane

Bacterial chromosome

Chromosomereplication

begins.

Figure 12.12-2

1

Origin ofreplication

E. coli cell

Two copies of origin

Cell wall

Plasma membrane

Bacterial chromosome

Origin Origin

Chromosomereplication

begins.

Replicationcontinues.

2

Figure 12.12-3

1

Origin ofreplication

E. coli cell

Two copies of origin

Cell wall

Plasma membrane

Bacterial chromosome

Origin Origin

Chromosomereplication

begins.

Replicationcontinues.

Replicationfinishes.

2

3

Figure 12.12-4

1

Origin ofreplication

E. coli cell

Two copies of origin

Cell wall

Plasma membrane

Bacterial chromosome

Origin Origin

Chromosomereplication

begins.

Replicationcontinues.

Replicationfinishes.

Two daughtercells result.

2

3

4

Slide 27LE 8-3b

Prokaryotic chromosomes

Co

lori

zed

TE

M 3

2,5

00

Figure 12.15

G1 checkpoint

G1

G2

G2 checkpointM checkpoint

M

SControlsystem

Cell

Cycl

e

Cell

Cycl

e

Contr

ol

Contr

ol

Figure 12.16

G1 checkpoint

G1 G1

G0

(a) Cell receives a go-ahead signal.

(b) Cell does not receive a go-ahead signal.

CheckpointsCheckpoints

Slide 30

CancerCancer

• Kills 1 out of 5 AmericansKills 1 out of 5 Americans

• Disease of the cell cycleDisease of the cell cycle

• Cells don’t respond to the normal cell cycle Cells don’t respond to the normal cell cycle checkpointscheckpoints

• Cancer cells DO NOT exhibit density or Cancer cells DO NOT exhibit density or anchorage dependenceanchorage dependence

• Cancer cells divide out of control and can Cancer cells divide out of control and can invade other parts of the bodyinvade other parts of the body

Figure 12.19

Anchorage dependence

Density-dependent inhibition

Density-dependent inhibition

(a) Normal mammalian cells (b) Cancer cells

20 m 20 m

Figure 12.20

Glandulartissue

Tumor

Lymph vesselBloodvessel

Cancercell

Metastatictumor

A tumor growsfrom a singlecancer cell.

Cancer cells invade neighboring

tissue.

Cancer cells spreadthrough lymph andblood vessels to other parts of the

body.

Cancer cells may survive and establisha new tumor

in another part of the body.

4321

Figure 12.UN01

Mitosis

Cytokinesis

MITOTIC (M) PHASE

G1

G2

S

Telophase andCytokinesis

AnaphaseMetaphase

Prometaphase

Prophase

I T R HASEE PN

Figure 12.UN05

Figure 12.UN04