REVIEW of MITOSIS Vs

NOTE:

Diploid =

Has BOTH mom AND dad’s chromosome

Example:

In a cell, if it has chromosome number 1 for dad and chromosome number 1 for mom

Haploid =

Has EITHER

Mom OR dad’s chromosome

Example:

In a cell, if it has chromosome number 1 for dad or chromosome number 1 for mom, but not both

MEIOSIS I

Interphase

- Growth to maturity (G1)

- DNA replication (S)

46 single to 92 single

- copies of both mom and dad (diploid)

- Replication of organelles (G2)

Prophase I

- Homologous chromosomes pair to form tetrad by synapsis

- Crossing over can occur

- Centrioles spread and spindles extend

- Polar spindles extend centriole to centriole

- Kinetochore spindles attach to centromeres of each double chromosome

Metaphase I

- tetrads are organized in the middle of the cell

- crossing over could occur

Anaphase I

- Spindles retract pulling the homologous chromosomes to opposite sides of the cell (disjunction) allowing independent assortment by

- Cleavage furrow is obvious

Telophase I

- Cleavage furrow continues until cytokinesis occurs

- 2 haploid cells form. They have, for ex, double chromosome 1 of mom or dad, not both in the same cell.

CHROMO-

SOME NUMBERS (MEIOSIS)

46 single

92 single

46 double (23 double mom and 23 double dad)

Homologous chromosomes find to make 23 tetrads

23 tetrads (total 46 chromosomes)

23 double chromosomes to one side, 23 double to the other side (random)

2 cells (23 double chromosomes in each, but mom’s double chromo. 1 in one cell, dad’s double chromo. 1 in another cell…haploid

CHROMO-

SOME NUMBERS (MITOSIS)

46 single (diploid)

92 single

46 double

46 single to one side and 46 single to other side

46 single in each cell (23 single mom and 23 single dad in

each cell.. diploid)

MITOSIS

Interphase

- Growth to maturity (G1)

- DNA replication (S)

46 single to 92 single

- copies of both mom and dad (diploid)

- Replication of organelles (G2)

Prophase

- Chromosomes pair to double chromosomes (made of identical single chromosomes)

- Centrioles spread and spindles extend

- Polar spindles extend centriole to centriole

- Kinetochore spindles attach to centromere

Metaphase

- Double chromosomes are organized in the middle of the cell

Anaphase

- Spindles retract pulling the chromatids (now single chromosomes) apart to opposite sides of the cell.

- Cleavage furrow is obvious

Telophase

- Cleavage furrow continues until cytokinesis occurs

- 2 identical cells form. They have copies of both mom and dad’s chromosomes (diploid)

MEIOSIS II

Begin with 2 haploid cells (example: one cell has mom’s chromosome 1 and the other cell has dad’s chromosome 1…..if the cell has mom or dad’s then haploid

Prophase II

- Double chromosomes present (mixture of mom and dad)

- Centrioles spread and spindles extend

- Polar spindles extend centriole to centriole

- Kinetochore spindles attach to centromere

Metaphase II

- Double chromosomes are organized in the middle of each cell

Anaphase II

- Spindles retract pulling the chromatids (now single chromosomes) apart to opposite sides of the cell.

- Cleavage furrow is obvious

Telophase II

- Cleavage furrow continues until cytokinesis occurs

- 4 haploid sex cells form. In men, 2 are same as each other, while the other 2 are the same as one another.

CHROMO-

SOME NUMBERS (MEIOSIS)

2 cells with 23 double in each (haploid)

2 cells with 23 single to one side and 23 single to other side of each cell

23 single in each of the 4 cells (haploid)