Meiosis

interphase.

A cell preparing to undergo meiosis duplicates its chromosomes during

Nondisjunction

An accident of meiosisor mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to seperate at anaphase

Somatic

Any cell in a multicellular organism except sperm or egg cell or a cell that develops into a sperm or egg.

Crossing Over

the exchange of segments between chromatoids of homologous chromosomes during synapsis in prophase 1 of meiosis; also, the exchange of segments between DNA molecules in prokaryotes

Mutation

A change in the nucleotides sequence of an organism's DNA; mutation also can occur in the DNA or RNA of a virus; the altimate source of genetic diversity

Autosome

A chromosome not directly involved in determining the sex of an organism, in mammals, any chromosome other than X or Y.

Sex chromosome

A chromosome that determines whether an individual male or female

Tetrads

A paired set of homologous chromosomes, each composed of two sister chromatoids. Tetrads form during prophase 1 of meiosis

Gamete

A sex cell; a haploid sperm or egg. The union of two gametes of opposite sex (fertilization) produces a zygote

four types of mutation

Deletion-a piece of DNA is lost, missing,etc. Duplication- a piece of DNA is add, replicated,more than once Inversion-a pirce of DNA breaks off and reattaches in reverse order Translocation-two chromosomes involved a piece of DNA breaks off one chromosomes and attaches to a differant chromosomes

prophase I.

During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

homologous chromosomes stick together in pairs.

During prophase I of meiosis

Diploid

In a organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one set inherited from each parent; a 2n cell has 46 chromosomes

Meiosis

In a sexually reproducing organism, the division of a single diploid nucleus into four haploid daughter nuclei. produce haploid gametes from diploid cells in the reporductive organs of the parents

Haploid

In the life cycle of an organism that reproduces sexually, a cell contains a single set of chromosomes; a n cell has 23 chromosomes

four haploid cells.

Meiosis starts with a single diploid cell and produces

four phases for mitosis

Prometaphase, Metaphase, Anaphase, Telophase

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

The correct order of events during meiosis is what?

Mitosis

The division of a single nucleus into two genetically identical daughter nuclei. make up the mitotic (M) phase of the cell cycle

homologous Chromosomes

The two chromosomes that make up a matched pair in a diploid cell. They are of the same length, centromere position, and staining pattern and possess gene for the same characteristics at corrosponding loci. One homologous chromosomeis inherited from the organism's father, and one grom the mother

Karyotypes

a display of micrographs of the metaphase choromosomes of a cell, arranged by size and centromere position

Sister chromatoids

one of the two identical parts of a duplicated chromosome in a eukaryotic cell