Mitosis and Meiosis

Mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

Prophase I (Meiosis)

homologous chromosomes pair up and crossing over occurs

Metaphase I (Meiosis)

homologous pairs (tetrads) align at the equatorial plane and each pair attaches to a separate spindle fiber at the kinetochore

Anaphase I (Meiosis)

Homologous chromosomes separate

Telophase I (Meiosis)

Cytokinesis occurs, the result are two haploid daughter cells

Prophase II

The duplicated chromosomes and spindle fibers reappear in each new cell.

Metaphase II

The duplicated chromosomes move to the centre of the cell. Each centromere attaches to two spindle fibers instead of one.

Anaphase II

Centromeres divides. chromatids move to the opposite poles of the cells.

Telophase II

Nuclear membrane reforms, cytoplasm divides, 4 daughter cells formed

Cytokinesis

division of the cytoplasm

Diploid

containing two complete sets of chromosomes, one from each parent.

Haploid

An organism or cell having only one complete set of chromosomes.

Gamete

sex cell

somatic cells

Any cells in the body other than reproductive cells

Zygote

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Karyotype

A picture of all the chromosomes in a cell arranged in pairs

homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

genetic variation in meiosis

Results in cells that are genetically different as the result of crossing over and independent assortment

crossing over/recombination

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

independent assortment of chromosomes

The random distribution of maternal and paternal chromosomes into gametes during meiosis.

Random segregation of chromosomes

chromosomes in meiosis are separated randomly to produce gametes

asexual reproduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.

binary fission

A form of asexual reproduction in which one cell divides to form two identical cells.

Budding (asexual)

when a new organism grows out of the parent's body

Fragmentation

A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals.

Spores

Asexual reproductive or resting cell capable of developing into a new organism without fusion with another cell, in contrast to a gamete

Vegetative

reproduction of plants by direct cloning from existing plants