Unit 2 Meiosis

homologous chromosomes

Pair of chromosomes that are SIMILAR size and appearance. Contain the same genes but may have different alleles.

crossing over

Exchange of genetic material between homologous chromosomes during prophase I of meiosis

haploid cell

A cell containing only ONE set of chromosomes (n). In mammals containing 23 chromosomes. Sperm and egg cells.

diploid cell

A cell containing TWO sets of chromosomes (2n), one set inherited from each parent. In mammals, containing 46 chromosomes.

meiosis

A type of sexual cell division that results in FOUR daughter cells each with HALF the number of chromosomes of the parent cell; results in gamete formation.

mitosis

Cell division in which the nucleus divides into TWO daughter cells containing the SAME number of chromosomes which are EXACT copies of the parent.

mutation

Change in a DNA sequence that affects genetic information

genetic variation

Differences among individuals in the composition of their genes or other DNA segments

somatic cells

Any cells in the body other than reproductive cells

gametes

Sex cells (sperm and egg)

haploid

chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.

chromatid

One of two identical "sister" parts of a duplicated chromosome

centromere

The area where the chromatids of a chromosome are attached

karotype

The arrangement of the homologous pairs of chromosomes from tallest to shortest.

male karyotypes have ______________

One X and one Y chromosome

female karyotypes have ______________

Two X chromosomes