Chapter 8 CELL DIVISION

I. Why Do Cells Divide?II. The Cell Cycle in ProkaryotesIII. The Cell Cycle in Eukaryotes A. The Cell Cycle and Mitosis and Cancer B. Meiosis 1. Chromosome Numbers 2. The Human Life Cycle 3. Meiotic Cell Division: Meiosis I and II 4. Biological significance C. Comparison of Mitosis and Meiosis

I. Why Do Cells Divide? - for ________________, and _____________

(asexual or sexual)

Paramecium: Asexual reproduction

Yeasts: Asexual reproduction (Budding)

Growth and Development

II. The Cell Cycle and Cell Division in Prokaryotes

*Cell division involves _________________*Chromosomes - packages of ___________, the hereditary

material (+ proteins)

*Gene - a segment of __________ that encodes

for a protein, which in turn is responsible for a particular trait

1attachment site

cellwall

plasmamembrane

circular DNA

3

4

5

2

Fig. 8-3

p. 114

_______________

(asexual reproduction in bacteria)

II. The Cell Cycle in Prokaryotes

III. The Cell Cycle and Cell Division in Eukaryotes

A. The Cell Cycle and Mitosis

Mitosis:

- occurs in ________ cells (body cells)

- daughter cells are genetically __________________

Fig. 8-7 p. 117

The Cell Cycle

in Eukaryotes

G1

G2

S

Fig. 8-10. Cytokinesis in animal cells: _______________________ formation

(Telophase) p. 123

Figure 8-11. Cytokinesis in Plant Cells: ______________________ formation

(Telophase) p. 123

(d) Anaphase: Sister chromatids have separated, and one set has moved toward each pole.

(a) Interphase in a seed cell: Thechromosomes (blue) are in thethin, extended state and appearas a mass in the center of thecell. The spindle microtubules(red) extend outward from thenucleus to all parts of the cell.

(b) Late prophase: The chromosomes (blue) have condensed and attached to the spindle microtubules (red).

(e) Telophase: The chromosomes have gatheredinto two clusters, one at thesite of each future nucleus.

(c) Metaphase: The chromosomeshave moved to the equator of the cell.

(f) Resumption of interphase: Thechromosomes are relaxing againinto their extended state. The spindlemicrotubules are disappearing,and the microtubules of the twodaughter cells are rearranging intothe interphase pattern.

Cell Cycle & Mitosis in a Plant Cell

Mitosis in Whitefish Blastula

WHITEFISH CELLS (MITOSIS)

Mitosis in Onion Root Tip

p. 119

HEALTH WATCH:

CANCER

p. 119

HEALTH WATCH:

CANCER

III. B. Meiosis

1. Chromosome Numbers

homologous pair of chromosomes - similar in size, shape and

_______________________________

diploid (2N) - _____ sets of chromosomes (full

complement)

haploid (N) - _________set of chromosomes

Fig. 8-6

p. 116

The karyotypeof a humanmale

Sex chromosomes

Organisms Chromosome #s

Bacteria 1

Human 46 (23 pairs)

Cat 38

Dog 78

Corn 20

Amoeba 50

Chimpanzee 48

juvenile

fertilized egg

mitotic cell division,differentiation and growth

fusionof gametes

sperm

egg

mitotic cell division, differentiation, and growth

adults

meiotic cell division(in testes)

meiotic cell division(in ovaries)

Fig. 8-8 p. 118

(N)

(2N)

(N)

III. B. 2. The Human Life Cycle

III. B. Meiosis

3. Meiotic Cell Divisions: Meiosis I & II

a) occurs in ___________sex cells (germ cells)

b) produces ______________ gametes that are

genetically ______________________

Fig. 8-12 p. 124

Fig. 8-12 p. 125

Fig. 8-14 Crossing Over (Prophase I)

Fig. 8-13 p. 127

a) The four possible arrangements of homologous pairs at Metaphase I

The 8 possible sets of chromosomes after Metaphase I

III. B. Meiosis

4. Biological Significance

a) Meiosis is the key to ______________

b) __________ reproduction is possible

c) Ensures that the of each species is maintained

throughout generations

III. C. Comparison of Mitosis and Meiosis (in Animal Cells)

Table 8-1 p. 127

Feature Mitosis Meiosis

Cells in which it occurs __________ or body cells Gamete-producing cells

Number of daughter cells 2 , genetically _________ 4 , genetically different

Final chromosome # Diploid Haploid

Number of cell divisions 1 2

Function in animals Development, growth, Gamete production for

repair and maintenance; sexual reproduction

asexual reproduction