Cell DivisionCell DivisionRubie Maranan-Causaren

The cell cycle.

DNA REPLICATIONREPLICATION

G1

Phases Activities

Interphase

G1

SCell cycle G2

MitosisCell Division Karyokinesis

Meiosis

Cytokinesis

Interphase

• Nucleus• Nuclear membrane• Nucleoli• Chromatin network

ProphaseProphase

Figure 9 3Figure 9.3

MetaphaseMetaphase

Anaphase

Telophasep

WhitefishWhitefish blastula

onion rootonion root tipp

t i lcentrioles

MITOSIS

INTERPHASE

Figure 6.3. Mitosis. This type of nuclear division ensures that each daugther cell has same chromosomal number (diploid=2n) as that of the parent cell.

Film clip

Film clip2Film clip2

MEIOSIS

Chromosome number?

(double threads)

“synapsis and

Homology search

“synapsis and crossing over”

(thick threads)

search

“rough pairing” (yolked threads)

Figure 6.4. Meiosis. A diagrammatic representation of the major events occurring during meiosis (example in a male animal with a diploid number of 4).

rough pairing

(Thin threads)

(yolked threads)

Karyotype1Karyotype1

Karyotype2

Karyotype3

Figure 10 1Figure 10.1

Chiasma and crossing overChiasma and crossing over

How meiosis works

Stages of meiosis

Random orientation of chromosomes

spermatogenesisspermatogenesis

SpermatogenesisSpermatogenesis

(2n) (n) (n) (n) (n)(2n)

spermatogonium

Meiosis vs. mitosis

C it i Mit i M i iCriteria Mitosis MeiosisKinds of cells somatic cells gametes (egg and sperm)no. of division/s per cycle one two

f d ht ll f d l t fno. of daughter cells formed per cycle two fourchromosome no. of daughter cells diploid (2n) haploid (n)progeny/daughter cells genetically identical genetically differentti f l th h t lif l t d ft ltime of cycle throughout life completed after sexual

maturity (in humans)uses growth, repair, and sexual reproduction,

asexual reproduction generating new geneasexual reproduction generating new genecombinations

Figure 10 8Figure 10.8

Salamat……..