MitMei Review

ap bio Meiosis and Mitosis

Prophase

chromatids supercoils to create chromosomes

Metaphase

chromosomes align at the metaphse plane

Anaphase

sister chromosomes seperate an migrate to opposite poles of the spindle.

Telophase

Chromosomes arrive around poles (loose diffuse)

Sister Chromatids

They are the copied DNA, and the two halves of a chromosome. They are condensed to be prepared for nuclear division and they have identical nucleus acid sequence until phase.

Mitosis

-only involves one cycle of division
-follows a single S-Phase
-It is conservative
-two daughter nuclei genetically identical to parent nucleus
-following cytokineses the result of daughter cells are clones of the parent cell.

Meiosis

-reductive form of annular division
-chromosome count is in a diploid organism is reduced to the haploid state
- requires 2 stages of nuclear division
- in prophase 1 homologous chromosomes pair by synapis
- in Anaphase 1 homologous produce two haploid daughter nuclei.
- meiosis 2 involves separation of the sister chromatids with a haploid chromosome count

Cytokenisis

division of cytoplasm and cell itself.

What does meiotic division promote?

karyocytosis reduces the chromosome count, to facilitate sexual recombination. homologous pair and align randomly at metaphase 1, the popl. generates sex cells with unique combination of chromosomes. Chiasma forms between homologous may result in crossing-over in generation of hybrid chromosomes (increasing genetic diversity).

It also promotes sexual reproduction

crossing over

an exchange of equivalent chromosome regions

Synapsis

DNA replication during interphase

Chiasma

When homologous weakens, move apart, and reveal contact between chromatids. causes cross over

Meiosis

results in new combinations of chromosomes

Homologous chromosomes

consists of a pair chromosomes in diploid organism, in which on of the pair came from the father (sperm) and the other came from the mother (egg). which are combined by fertilization. They look alike and care forms of genes for the same traits.

diploid

two complete sets of chromosomes in an organism's cells, and each parent contributes to each pair of chromosomes

haploid

a cell that contains a single set of chromosomes

meiosis two

the homologous chromosomes pair and then separate as there is just one cycle of DNA replication, it involves a haploid number of chromosomes.

Prophase 1 (meiosis)

homologous unlike mitosis, chromosomes pair by synapsis

what is the number of new combinations of chromosomes?

2^N where N equals the haploid number.

is meiosis conservative or reductive?

it is a reductive process of nuclear division by which the nucleus of the sell is replicated twice, producing 4 unique haploid daughter nuclei

is mitosis conservative of reductive?

it is a conservative process of nuclear division the cell is replicated once, producing two identical daughter cells.

How does Meiosis differ from Mitosis?

the homologous chromosomes pair during prophase 1 of meiosis 1. there is just one cycle of DNA replication, Meiosis 2 involves a haploid number of chromosomes. Mitosis only needs one cycle of nuclear division, that is followed by an S-phase (synapsis).

a cell that contains pairs of homologous chromosome is said to be

diploid