Meiosis and Genetic Variation Practice Flashcards

A set of vocabulary flashcards covering the stages of meiosis, the origins of genetic variation, and the consequences of chromosomal errors such as nondisjunction.

Meiosis

A process involving two rounds of division that results in the formation of four haploid cells.

Crossing Over

The recombination of genetic information that produces gene combinations different from those carried by parental chromosomes.

Meiosis I

The first round of meiosis where two haploid cells form and chromosomes are still doubled.

Meiosis II

The second round of cell division during which sister chromatids separate, resulting in four haploid daughter cells containing single chromosomes.

Independent Assortment of Chromosomes

The principle where every chromosome pair orients independently of all others at metaphase I.

Total number of possible chromosome combinations in a gamete

Represented by the formula $2^n$.

Random Fertilization

The random fertilization of a human egg cell by one sperm, which can result in more than $64 \text{ trillion}$ different possible chromosome combinations in a zygote.

Nondisjunction

A mistake in meiosis where members of a chromosome pair fail to separate at anaphase (during meiosis I or II), producing gametes with an incorrect number of chromosomes.

Abnormal karyotype

The result of an organism surviving nondisjunction, likely leading to medical disorders caused by an abnormal number of genes.

Down Syndrome (Trisomy 21)

A condition caused by an extra chromosome $21$, affecting approximately $1$ out of every $700$ children.

Evolutionary advantage of asexual reproduction

Conveys an advantage when plants are sparsely distributed or well-suited to a stable environment; eliminates the need to expend energy forming gametes and copulating.

Evolutionary advantage of sexual reproduction

Speeds adaptation to a changing environment and allows a population to more easily rid itself of harmful genes.