Forming a New Life: Genetics and Prenatal Development

Vocabulary flashcards covering human reproduction, genetic principles, chromosomal disorders, gene-linked abnormalities, developmental stages, and prenatal diagnostic testing.

Genomics

The study of the functions and interactions of various genes.

Ova

Female reproductive cells that begin maturing at puberty and are released monthly into a fallopian tube, propelled by cilia; if unfertilized, they result in menstrual flow.

Sperm

Self-propelled male reproductive cells that are smaller than ova, where Y-chromosome sperm swim faster than X-chromosome sperm; approximately $200$ to $400$ million are released per ejaculation, with $1$ in $1,000$ reaching the ovum.

Monozygotic Twins

Twins that develop from a single zygote that splits in two, resulting in genetically identical individuals.

Dizygotic Twins

Twins derived from two separate zygotes who share $50\%$ of their genetic material.

Carrier

An individual who is unaffected by a genetic disorder but holds and can pass on the gene for that disorder to offspring.

Polygenic Inheritance

The pattern of inheritance in which most traits (such as height) are determined by the interaction of several genes.

Genotype

An individual's actual genetic makeup or specific combination of alleles.

Phenotype

The observable physical or biochemical expression of genetic makeup, which is the product of the genotype.

Down Syndrome

An autosomal chromosomal disorder caused by an extra $21\text{st}$ chromosome (Trisomy 21), responsible for $40\%$ of moderate to severe mental retardation.

Turner Syndrome

A chromosomal condition affecting individuals assigned female at birth, characterized most commonly by short stature and early loss of ovarian function.

Klinefelter Syndrome

A chromosomal condition (XXY) in which boys and men are born with an extra X chromosome.

Fragile X Syndrome

A genetic condition causing developmental problems, learning disabilities, and cognitive impairment, usually affecting males more severely and causing speech and language delays by age $2$.

XYY Syndrome

A rare chromosomal disorder affecting males, characterized by tall stature, severe adolescent acne, normal range intelligence (with IQ averaging $10\text{--}15$ points lower than siblings), and potential behavioral or learning issues.

Cystic Fibrosis

A gene-linked abnormality involving glandular dysfunction that hampers breathing and digestion by interfering with mucus production.

Phenylketonuria (PKU)

A gene-linked metabolic disorder that causes mental retardation if untreated, but can be controlled with a special diet to allow average intelligence.

Sickle-Cell Anemia

A gene-linked blood disorder that limits the body's oxygen supply, leading to potential joint swelling, heart failure, and kidney failure.

Spina Bifida

A gene-linked neural tube disorder that causes brain and spine abnormalities.

Tay-Sachs Disease

A gene-linked disorder caused by lipid accumulation in the nervous system, leading to deceleration of mental and physical development and death usually by $5$ years of age.

Karyotype

A chart showing an individual's complete set of chromosomes, used in genetic counseling to identify chromosomal abnormalities.

Heritability

A statistical estimate of the proportion of trait variance within a population that is attributable to genetic (heritable) influences.

Epigenetics

The study of environmental factors putting their stamp on genes (epigenome), causing changes to gene and cell activity without changing the underlying DNA sequence.

Non-Shared Environment

Unique environmental influences and experiences that differ among siblings growing up in the same family.

Germinal Stage

The period of prenatal development from fertilization to Week $2$, characterized by cell division and implantation of the blastocyst into the uterine wall.

Zygote

A single-celled organism created by the fusion of sperm and egg, containing $23$ paired chromosomes ($50\%$ inherited from each parent).

Embryonic Stage

The period of prenatal development from Week $2$ to Week $8$, during which major organ systems differentiate.

Cephalocaudal Trend

A developmental pattern in which growth and motor control proceed directional from head to toes.

Proximodistal Trend

A developmental pattern in which growth and development proceed outward from the center of the body toward the extremities.

Fetal Stage

The prenatal period from Week $8$ until birth, during which major organ systems are formed, fingers and toes develop, and visual determination of sex becomes possible.

Rubella

A maternal infection that can cause miscarriage, stillbirth, or deafness if contracted by the mother at $12$ weeks of pregnancy or earlier.

DES (Diethylstilbestrol)

A hormone formerly administered to pregnant women to prevent miscarriage that caused reproductive organ cancer or poor sperm quality in offspring.

Toxoplasmosis

A parasitic infection contracted from rare/uncooked food or the intestinal tract of cats that poses severe risks to a developing fetus.

Rh Incompatibility

A condition occurring when an Rh-negative mother carries an Rh-positive fetus, leading to antibody production (especially after blood mixes during delivery) that can attack Rh-positive red blood cells in a subsequent pregnancy.

Ultrasound

A prenatal diagnostic procedure using sound waves to produce images of organs, tissues, and internal body structures.

Fetal MRI

A prenatal diagnostic imaging test that utilizes a magnetic field rather than radiation to provide detailed, high-resolution images of fetal anatomic structures.

Chorionic Villus Sampling (CVS)

A prenatal diagnostic test involving tissue sampling from the placenta to evaluate for chromosomal abnormalities and genetic conditions.

Amniocentesis

A prenatal diagnostic procedure where amniotic fluid is withdrawn from around the fetus in the uterus to test for health and chromosomal conditions.

Triple Screen Test

A maternal blood screening test measuring alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol, characterized by $70\%$ sensitivity and a $5\%$ false-positive rate.