Meiosis and Mitosis, Mitosis and Meiosis

meiosis

type of cell division that results in 4 daughter cells that each have half the number of chromosomes as the parent cell.

Diploid

A cell containing two full sets of chromosomes

Haploid

A cell containing a single/ half set of chromosomes

Gametes

A haploid male or female germ cell (e.g. sperm and egg)

gene

a section of the DNA (chromosome) that codes for a specific trait (e.g. eye color or hair color)

crossing over

when homologous chromosomes exchange genes during Prophase 1 creating new mixture of parent traits in their offspring

Meiosis I

PMAT I: The first cell division of meiosis when the homologous pairs are split up into two separate cells.

Meiosis II

PMAT II: The second cell division of meiosis. This is when the sister chromatids are split up into two separate cells.

Mitosis

Produces cells that are genetically identical

23 pairs of chromosomes

How many pairs of chromosomes present in humans

Chromosome

Coiled up DNA surrounded by protein

Homologous Chromosomes

Carry the same genes at the same locus (location).
Ex. Chromosome 1 and Chromosome 1

Somatic cell

Body cell

Function and location of Mitosis

Cell division for growth, repair or maintenance. Occurs in somatic cells.
PMAT

Function and location of Meiosis

Cell division for gamete production (sperm and eggs). Happens in gonads (ovaries and testes).

Phases of the Cell Cycle

1. Interphase (G1, S, G2)
2. Mitosis (PMAT)
3. Cytokinesis (cell division)

Parts of Interphase

DNA is chromatin
G1

Events in Prophase in mitosis

Chromatin coils up into chromosomes.
Centrioles move to poles.
Spindle fibres and asters form. Nucleus and nucleolus
disappear.

Events in Metaphase in mitosis

Chromosomes line up at the middle of the cell
MIDDLE

Anaphase in mitosis

APART! Centromeres divide.

Telophase

Two new nuclear envelopes reform around chromosomes at the opposite ends of the cell

Cytokinesis

Cell divides into two.

Sexual Reproduction

Requires male and female gametes. Variation.

Crossing over

Homologous chromosomes may exchange genetic material during prophase I.

Prophase I

Homologous chromosomes pair up.
Crossing over may occur

Metaphase I

Homologous pairs line up in the middle on the metaphase plate.

Anaphase I

Segregation

Telophase I

Cleavage furrow. Replicated chromosomes reach the poles.

Prophase II

Chromosomes can be seen.
Cells are haploid (n).

Metaphase II

Chromosomes line up in the middle

Anaphase II

Centromeres split. Single chromosomes move apart.

Independent Assortment

The way the homologous pairs line up in Metaphase I is RANDOM!