Classical Genetics: Meiosis and Gametogenesis

These vocabulary flashcards cover the biological processes of meiosis, chromosomal abnormalities, human gamete structure, and the stages of fertilization based on the lecture transcript.

Zygote

The cell formed by the fusion of an egg cell and a sperm cell, containing twice as much genetic material as a single gamete.

Meiosis

A special cell division used in connection with sexual reproduction that results in cells with half of the genetic material of the original cell.

Haploid

Refers to organisms or cells containing a single set of chromosomes.

Diploid

Refers to organisms or cells containing two sets of chromosomes.

Centromere

The region of a chromosome where sister chromatids are joined and where spindle fibers attach during division.

Homologous Pair

A pair of chromosomes (one maternal and one paternal) that are of the same type and lay next to each other during prophase I.

Autosomes

The "normal" chromosomes that are not involved in determining the sex of an individual; humans have 44.

Gonosomes

The sex chromosomes (XX in females and XY in males) that determine the genetic sex of an individual.

Bivalent

A structure formed during prophase I when homologous double-chromatid chromosomes lay next to each other.

Crossing Over

The process during prophase I where homologous chromosomes exchange pieces of genetic material.

Interchromosomal Recombination

The random distribution of maternal and paternal homologous chromosomes to the poles during anaphase I.

Intrachromosomal Recombination

The increase in genetic variability caused by the exchange of chromosome pieces during crossing over.

Chiasma

The visible point under a microscope where crossing over occurs between homologous chromosomes.

Non-disjunction

A mishap in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly during meiosis.

Aneuploidy

A condition in which an offspring has an abnormal number of a particular chromosome (an "uneven number situation").

Trisomic

An aneuploid cell that has a chromosome present in triplicate, totaling $2n+1$ chromosomes.

Monosomic

An aneuploid cell that is missing a chromosome, totaling $2n-1$ chromosomes.

Down Syndrome

A condition known as Trisomy 21, characterized by short stature, characteristic facial features, and mental retardation.

Turner-syndrome

A female gonosomal monosomy ($45: 44+X0$) characterized by short height, webbed neck, and sterility.

Klinefelter-syndrome

A male gonosomal condition ($47: 44+XXY$) where individuals are often taller than average and sterile.

Barr Body

A condensed, inactive X chromosome found in the cells of female mammals.

Spermatozoon

A male gamete produced in the testes inside seminiferous tubules.

Acrosome

A membrane-bound compartment at the tip of the sperm head containing hydrolytic enzymes used to drill through the egg shell.

Sertoli Cells

Large, non-dividing "nurse cells" that nourish developing sperm cells within the testicular tubules.

Zona Pellucida

A protective layer of glycoproteins secreted by granulosa cells that surrounds the egg cell.

Spermatogenesis

The process of sperm production that takes approximately 64 days and results in four haploid spermatids from one spermatocyte I.

Oogenesis

The production of egg cells which begins in the female embryo and is arrested in prophase I until puberty.

Polar Bodies

Small "rest cells" formed during the unequal cytokinesis of oogenesis that eventually degenerate.

Acrosomal Reaction

The process where the sperm releases hydrolytic enzymes into the zona pellucida to reach the egg's plasma membrane.

Cortical Reaction

The release of enzymes from cortical granules that hardens the zona pellucida to block additional sperm and prevent polyspermy.