Mitosis – Cellular Division

Blastocyst- fluid filled ball of cells

• 2 types of cells:

-cells to become placenta - trophoblast

-inner cell mass (stem cells)

Stem cells are pluripotent

-have ability to read all DNA in their nuclei.

-can become any cell

In 5 to 6 days lose this ability

Blastocyst implants in uterus

Gastrula

Giant squidGiant squidgenusgenus(Architeuthis)

1 nerve cell = 39 ft1 nerve cell = 39 ft

Fig. 13-2b

(b) Redwoods

Fig. 12-2a

100 µm

(a) Reproduction

Fig. 12-2b

200 µm

(b) Growth and development

Fig. 12-2c

20 µm

(c) Tissue renewal

Fig. 13-2a

(a) Hydra

0.5 mm

Bud

Parent

Fig. 12-14

SG1

M checkpoint

G2M

Controlsystem

G1 checkpoint

G2 checkpoint

Fig. 12-15

G1

G0

G1 checkpoint

(a) Cell receives a go-ahead signal

G1

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

DNA – lots of it in a small space

chromatin

chromosome

Fig. 12-UN3

Fig. 12-40.5 µm Chromosomes

Chromosomeduplication(including DNAsynthesis)

Chromo-some arm

Centromere

Sisterchromatids

DNA molecules

Separation ofsister chromatids

Centromere

Sister chromatids

Fig. 12-UN1

Telophase andCytokinesis

Anaphase

Metaphase

Prometaphase

Prophase

MITOTIC (M) PHASE

Cytokinesis

Mitosis

SG1

G2

Fig. 12-20

Tumor

A tumor growsfrom a singlecancer cell.

Glandulartissue

Lymphvessel

Bloodvessel

Metastatictumor

Cancercell

Cancer cellsinvade neigh-boring tissue.

Cancer cells spreadto other parts ofthe body.

Cancer cells maysurvive andestablish a newtumor in anotherpart of the body.

1 2 3 4

Fig. 12-UN4

Fig. 12-UN6

Fig. 12-6b

PrometaphaseProphaseG2 of Interphase

Nonkinetochoremicrotubules

Fragmentsof nuclearenvelope

Aster CentromereEarly mitoticspindle

Chromatin(duplicated)

Centrosomes(with centriolepairs)

Nucleolus Nuclearenvelope

Plasmamembrane

Chromosome, consistingof two sister chromatids

Kinetochore Kinetochoremicrotubule

Prophase

• Chromatin – coils and supercoils to form chromosomes

• Nucleoli disappear

• Nuclear membrane disappear

• Spindle begins to form as microtubules grow out of centrosomes (centrioles)

• Microtubules from spindle attach to kinetochores on chromosomes

Fig. 12-3

20 µm

Fig. 12-6d

Metaphase Anaphase Telophase and Cytokinesis

Cleavagefurrow

Nucleolusforming

Metaphaseplate

Centrosome atone spindle pole

SpindleDaughterchromosomes

Nuclearenvelopeforming

Metaphase

• Spindle fully formed

• Poles at opposite end of cell

• Chromosomes now on metaphase plate (middle of cell)

Fig. 12-7

Microtubules Chromosomes

Sisterchromatids

Aster

Metaphaseplate

Centrosome

Kineto-chores

Kinetochoremicrotubules

Overlappingnonkinetochoremicrotubules

Centrosome 1 µm

0.5 µm

Anaphase

• 2 centromeres of each chromosome come apart separating sister chromosomes

• Free chromatid now called a chromosome

• Spindle fibers attached to chromosomes kinetochores contract while those not attached lengthen.

• Poles move further apart and cell elongates

Fig. 12-10d

Anaphase4

Telophase

• Cell continues to elongate

• Nuclear membrane reforms

• Nucleolus forms

• Mitotic spindle disappears

• Cytokinesis occurs

• 2 genetically identical daughter cells form

Cytokinesis

• Division of the cytoplasm

• Occurs along with telophase

• Animal cells form a cleavage furrow which pinches the cell into 2

• Plant cells form a cell plate

Fig. 12-10e

Telophase5

Cell plate10 µm

Cleavage furrow

Fig. 12-9a

100 µm

Daughter cells

(a) Cleavage of an animal cell (SEM)

Contractile ring ofmicrofilaments

Fig. 12-9b

Daughter cells

(b) Cell plate formation in a plant cell (TEM)

Vesiclesformingcell plate

Wall ofparent cell

New cell wallCell plate

1 µm

Fig. 12-9

Cleavage furrow100 µm

Contractile ring ofmicrofilaments

Daughter cells

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

Vesiclesformingcell plate

Wall ofparent cell

Cell plate

Daughter cells

New cell wall

1 µm

Fig. 12-UN2

Fig. 12-UN5

Mitosis video

Fig. 12-16

Pro

tein

kin

as

e a

cti

vit

y (

– )

% o

f d

ivid

ing

ce

lls (

– )

Time (min)300200 400100

0

1

2

3

4

5 30

500

0

20

10

RESULTS

Fig. 12-17

M G1S G2

M G1S G2

M G1

MPF activity

Cyclinconcentration

Time(a) Fluctuation of MPF activity and cyclin concentration during the cell cycle

Degradedcyclin

Cdk

G 1S

G 2

M

CdkG2

checkpointCyclin isdegraded

CyclinMPF

(b) Molecular mechanisms that help regulate the cell cycle

Cy

clin

ac

cu

mu

latio

n

Fig. 12-17a

Time(a) Fluctuation of MPF activity and cyclin concentration during the cell cycle

Cyclinconcentration

MPF activity

M M MSSG1 G1 G1G2 G2

Fig. 12-17b

Cyclin isdegraded

Cdk

MPF

Cdk

MS

G 1G2

checkpoint

Degradedcyclin

Cyclin

(b) Molecular mechanisms that help regulate the cell cycle

G2

Cyclin

accum

ulatio

n

Fig. 13-3APPLICATION

TECHNIQUE

Pair of homologousreplicated chromosomes

5 µm

Centromere

Sisterchromatids

Metaphasechromosome

Fig. 13-3a

APPLICATION

Fig. 13-3b

TECHNIQUE

Pair of homologousreplicated chromosomes

Centromere

Sisterchromatids

Metaphasechromosome

5 µm

Fig. 13-4

Key

Maternal set ofchromosomes (n = 3)

Paternal set ofchromosomes (n = 3)

2n = 6

Centromere

Two sister chromatidsof one replicatedchromosome

Two nonsisterchromatids ina homologous pair

Pair of homologouschromosomes(one from each set)

Mitosis – Word Bank

Asters Centrioles Chromatids

Chromosome Cytoplasm Nucleus

Nucleolus Nuclear membrane

Spindle Fibers

Kinetochore Cleavage Furrow

Fig. 12-10a

Nucleus

Prophase1

Nucleolus

Chromatincondensing

Fig. 12-10b

Prometaphase2

Chromosomes

Fig. 12-10c

Metaphase3

Fig. 12-10d

Anaphase4

Fig. 12-10e

Telophase5

Cell plate10 µm