Genetics, Inheritance Patterns, and Human Reproductive Biology

Vocabulary practice flashcards covering Mendelian and complex inheritance patterns, reproductive anatomy, spermatogenesis, oogenesis, female hormonal cycles, and fertility factors.

Phenotype

The observable physical expression of an individual's allele combination or genotype, resulting from proteins.

Genotype

The specific genetic makeup or combination of alleles that an individual possesses for a particular trait.

Loci

The specific physical locations of genes on a chromosome.

Heterozygous

A genotype consisting of two different alleles for a given trait.

Homozygous

A genotype in which both alleles for a given trait are identical.

Law of Segregation

The genetic principle stating that homologous chromosomes separate during meiosis, ensuring that the two alleles for a particular gene move into separate haploid cells.

Law of Independent Assortment

The principle stating that traits and genes on non-homologous chromosomes are inherited independently of one another during the formation of haploid cells.

Dominant Allele

An allele version that masks the presence of a recessive allele during gene expression, requiring only one copy to express its phenotype.

Recessive Allele

An allele version that is only expressed phenotypically when no dominant allele is present in the genotype, requiring a homozygous state.

Autosomal Chromosomes

All non-sex chromosomes present in an organism, excluding the $X$ and $Y$ sex chromosomes.

Sex-linked Inheritance

An inheritance pattern for traits determined by alleles located specifically on sex chromosomes, typically the $X$ chromosome.

Incomplete Dominance

An inheritance pattern in which a heterozygous individual displays an intermediate phenotype between the dominant and recessive traits, such as wavy hair.

Co-dominant Trait

A genetic condition in which both alleles in a heterozygous individual are simultaneously expressed in the phenotype, as seen in $ABO$ blood types.

Polygenic Traits

Traits whose phenotypic outcome is governed by the combined interaction of several distinct genes, producing wide variations in genotype and phenotype.

Phenotypic Plasticity

The capacity of environmental factors to alter or influence how genes are expressed, contributing to variations in multifactorial traits.

SRY Region

A region on the $Y$ chromosome that, when activated, triggers the development of testes in the embryo.

Scrotal Sacs

External reproductive pouches containing the testes and epididymis that maintain testicular temperature below body temperature to preserve sperm count and quality.

Seminiferous Tubules

Coiled tubules located inside the testes where meiosis occurs and sperm are produced over a span of $64\text{ days}$.

Epididymis

The duct structure situated on the testes through which mature sperm travel en route to the vas deferens.

Vas Deferens

The muscular sperm duct that transports mature sperm from the epididymis to the urethra.

Seminal Vesicles

Male accessory glands that secrete an alkaline, sugar-rich fluid containing prostaglandins to protect and activate sperm within the female reproductive tract.

Bulbourethral Glands

Glands that secrete a pre-ejaculatory cleaning mucus into the urethra.

Prostate Gland

A male reproductive gland that secretes fluid to nourish sperm cells and lubricate the urethra.

Acrosome

The enzyme-filled cap at the tip of the sperm head that releases digestive enzymes to penetrate the outer membrane of an egg.

Semen

The combined fluid composed of sperm cells and secretions from the seminal vesicles, prostate, and bulbourethral glands.

Interstitial Cell Stimulating Hormone (ICSH)

A male pituitary hormone that acts directly on the testes to stimulate testosterone production.

Follicle Stimulating Hormone (FSH)

A hormone that initiates sperm production via meiosis in males starting at puberty, and triggers ovarian follicle growth and estrogen production in females.

Testosterone

The primary male hormone produced by the testes that masculinizes the brain and anatomy, drives sperm production, and promotes secondary sex characteristics.

Corpus Luteum

The glandular structure formed from an ovarian follicle after ovulation that produces progesterone and estrogen to sustain the uterine endometrium.

Polar Bodies

The three tiny, non-functional cells formed during female meiosis alongside the single large, nutrient-rich egg.

Oviducts

The fallopian tubes into which ovaries release eggs and where fertilization naturally occurs after eggs are caught by fimbriae.

Endometrium

The highly vascularized inner lining of the uterus that thickens to support embryo implantation and sheds during menstruation if fertilization does not occur.

Cervix

The narrow neck of the uterus that secretes cervical mucus and dilates during labor.

Luteinizing Hormone (LH)

A pituitary hormone whose mid-cycle spike triggers ovulation within $24\text{ hours}$, marking peak fertility.

Progesterone

A hormone produced by the corpus luteum that causes the uterine lining to thicken and mature, actively maintaining pregnancy.

Prolactin

A hormone that stimulates breast milk production and acts to suppress ovulation.

Estrogen

An ovarian hormone that stimulates female reproductive system development, secondary sex characteristics, healthy fat deposits, and endometrial thickening.

Menstrual Cycle

The recurring hormonal sequence that coordinates the maturation, thickening, and eventual shedding of the uterine endometrium.

Inter Uterine Insemination (IUI)

A fertility procedure where ovarian follicles are stimulated with hormones, monitored, and washed sperm are injected directly into the uterus to fertilize the egg in the oviduct.