Honors Biology Meiosis Practice/Review

Vocabulary practice and key numerical facts regarding meiosis, genetic variation, and chromosomal counts from the Honors Biology review.

Haploid

Cells, such as sex cells, created by meiosis that contain a $n$ number of chromosomes, or half of the genetic material.

Diploid

Body cells created by mitosis that contain a $2n$ number of chromosomes, or a full set of genetic material.

Homologous chromosomes

A pair of chromosomes (one maternal and one paternal) that contain the same genes but are not identical because they may have different versions.

Sister chromatids

Replicated chromosomes joined by a centromere that are identical.

Purpose of Meiosis

To create sex cells, also known as gametes.

Reduction division

A term for meiosis because the cell is dividing and the number of chromosomes is being reduced.

Meiosis I

The first division of meiosis where homologous chromosomes are separated.

Meiosis II

The second division of meiosis where sister chromatids are separated.

Zygote

The single cell created by the fusion of male and female gametes that develops into an embryo via mitosis.

Somatic cell

A body cell that contains a pair of each type of chromosomes, one maternal and one paternal.

Crossing over

The exchange of pieces of DNA between homologous chromosomes that occurs during meiosis I.

Synapsis

The process where homologous pairs come together very closely during meiosis I.

Tetrad

A structure formed during synapsis consisting of 2 duplicated chromosomes, or 4 sister chromatids.

Chiasmas

The specific locations along the homologues where DNA exchanges occur within a tetrad.

Recombinant chromatids

Newly formed chromatids that are no longer identical to the original because they have a brand new combination of genes following crossing over.

Chromosome combination formula

$2^n$, where $n$ is the haploid number, used to determine the total number of combinations of chromosomes meiosis can package into gametes.

Tiger bone cell chromosome count

$$38$$

Tiger sperm cell chromosome count

$$19$$

Human unique gamete combinations

For a single biological male, $2^{23}$ or about $8,000,000$ unique gametes.

Human unique offspring total

Approximately $64$ TRILLION unique offspring resulting from the possible combinations of sperm and egg.

Dog unique sperm cell combinations

$2^{39}$ or approximately $549,755,813,888$ (5.5 billion) unique sperm cells, based on a diploid number of $78$.