Chapter 11: Meiosis and Sexual Reproduction

These flashcards cover key concepts related to meiosis and sexual reproduction, including definitions, processes, and important terminology.

Ploidy

The number of chromosome sets in the nucleus, e.g., diploid (2n) for two sets, haploid (n) for one set.

Diploid

Organisms that have two sets of chromosomes, represented as 2n; humans have 46 chromosomes in somatic cells.

Haploid

Cells that contain a single set of chromosomes (n), such as human gametes which have 23 chromosomes.

Homologous chromosomes

A pair of chromosomes from each parent that have the same length, centromere position, and carry genes for the same traits.

Allele

An alternative version of a gene located at a specific position (locus) on a chromosome.

Meiosis

A type of cell division that reduces the chromosome number by half, creating four genetically unique haploid cells from one diploid cell.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Gametes

Specialized sex cells (sperm and egg) that are haploid, carrying only one copy of each chromosome.

Fertilization

The process in which a sperm and egg unite, resulting in the formation of a diploid zygote.

Independent assortment

The random distribution of maternal and paternal chromosomes into gametes during meiosis, contributing to genetic variation.

Crossing over

The exchange of genetic material between homologous chromosomes during Prophase I of meiosis, resulting in recombinant chromosomes.

Nondisjunction

An error in meiosis where homologous chromosomes or sister chromatids fail to separate, resulting in gametes with an abnormal number of chromosomes.

Oogenesis

The process of egg cell formation in females, involving meiosis and resulting in one viable ovum and polar bodies.

Spermatogenesis

The process of sperm cell formation in males, involving meiosis and producing four viable sperm from each primary spermatocyte.

Life Cycle

The series of stages in reproductive history of an organism, including diploid-dominant, haploid-dominant, and alternation of generations.

Tetrad

A structure formed during meiosis I, comprising a pair of homologous chromosomes, each consisting of two sister chromatids.

Genetic variation

Diversity in gene frequencies; arises from crossing over, independent assortment, and random fertilization during sexual reproduction.

Chiasmata

The points where homologous chromosomes connect and exchange genetic material during crossing over.

Zygote

The fertilized egg that results from the union of sperm and egg, which is diploid (2n) containing genetic material from both parents.