Lab 9 Human Genetics Chromosomal Inheritance During Meiosis

Which describes the cells at the end of meiosis I ?

-The cells are haploid. Though the chromatids are connected at the centromere, the cell is haploid because it has half the original chromosome number. - The homologous chromosomes are in separate cells.

Autosomes

22 pairs of chromosomes in humans that are identical for both sexes

Homologous Chromosomes

A pair of matching autosomes with similar genes

At what phase can Nondisjunction occur?

Anaphase I or II. When the chromosomes are aligned and begin to separate to opposite sides during anaphase I or II the separation may not occur correctly or completely, leading to Nondisjunction

Interkinesis

Brief pause between meiosis I and meiosis II in which no DNA replication occurs

Meiosis

Cell division required for gametogenesis. Cells contain half the amount of genetic material as the parent cell.

Nondisjunction during meiosis I

Failure of homologous chromosomes to separate during anaphase I. Produces one cell with extra homologous chromosomes and one cell missing a homologous chromosome.

Nondisjunction during meiosis II

Failure of sister chromatids to separate during anaphase II

Completion of meiosis process with nondisjunction during meiosis I

Final product of meiosis II if Nondisjunction occurs during anaphase I is two cells with an extra chromosome and two cells missing a chromosome.

What is the difference between meiosis I and meiosis II

Meiosis I separates homologous chromosomes and Meiosis II separates sister chromatids

Sister Chromatids

Replicated chromosomes composed of two identical attached copies

Gametogenesis

Spermatogenesis; produces sperm in males Oogenesis; produces ova in females. *oogenesis considered complete if fertilization occurs

Haploid

State of a cell with one copy of each chromosome. Human gametes have one copy of 23 chromosomes.

Diploid

State of a cell with two copies of homologous chromosomes. Humans have 23 pairs of chromosomes.

Meiosis I before Nondisjunction during Meiosis II

The cells at the end of meiosis I when Nondisjunction occurs during meiosis II are haploid with homologous pairs in separate cells

Meiosis II

The end of meiosis II produces four haploid cells