chapter 13

Fertilization

The union of sperm and egg that forms a zygote.

Asexual reproduction

Produces genetically identical offspring through methods like binary fission, budding, or vegetative reproduction.

Sex Chromosomes

Chromosomes that determine the sex of an individual (XX = female, XY = male).

Autosomes

Chromosomes that do not determine the sex of the organism; humans have 22 pairs.

Karyotype

A chromosome map showing homologous pairs, used to identify chromosomal abnormalities.

Homologous chromosomes

Chromosomes that are similar in size, shape, and gene content, containing the same genes but different alleles.

Meiosis

A two-step process that reduces chromosome number and leads to the formation of haploid cells.

Crossing Over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Independent Assortment

The random orientation of homologous chromosome pairs during metaphase I, contributing to genetic variation.

Oogenesis

The process by which female gametes are produced, typically resulting in one mature egg and three polar bodies.

Spermatogenesis

The process in males where all four haploid cells develop into viable sperm.

Genetic Variation

The diversity in gene frequencies among individuals, crucial for evolution and survival.

Mutations

Random changes in DNA sequences that can lead to new traits, enhancing survival or adaptability.

Lateral DNA Transfer

The horizontal gene transfer that allows genetic exchange among species and viruses.