Genetics and Development - Lecture Review

Vocabulary-style flashcards covering the basics of genetics, chromosomal disorders, gene-linked abnormalities, and prenatal testing methods.

Zygote

A single cell representing the start of human life, weighing approximately $1/20,000,000$ of an ounce.

Chromosomes

Thread-like structures contained within the nucleus of every human cell that carry genetic information.

Human Chromosome Count

Humans have $46$ chromosomes arranged into $23$ pairs.

Deoxyribonucleic acid (DNA)

A complex molecule with a double helix shape that contains our genetic information.

Genes

Short segments of DNA that serve as the basic units of heredity.

Mitosis

A process of cell division that results in a mother cell dividing into $2$ daughter cells.

Meiosis

A specialized form of cell division that produces gametes (sex cells) with $23$ chromosomes each.

Gametes

Sex cells (sperm and egg) that combine to create a zygote with $23$ chromosomes from each parent.

Genotype

An individual's actual genetic information.

Phenotype

The outward expression of genetic information, such as hair color, height, weight, and eye color.

Karyotype

A picture showing the number and visual appearance of a person’s chromosomes.

Autosomes

The first $22$ pairs of chromosomes in the human karyotype.

Sex Chromosomes

The $23rd$ pair of chromosomes, which determines biological sex ($XX$ for female, $XY$ for male).

Chromosomal Disorder

Situations where chromosomes are missing, changed, or additional copies are present.

Down Syndrome (Trisomy 21)

A disorder caused by an extra chromosome (total of $47$) characterized by a round face, flattened skull, and intellectual disabilities; risk increases to $1$ in $30$ for mothers aged $45$.

Klinefelter Syndrome

A disorder affecting biological males ($XXY$) causing small testicles, reduced testosterone, enlarged breasts, and potential learning disabilities.

Turner Syndrome

A disorder affecting biological females where they inherit only one X chromosome ($X0$), leading to short stature, webbed neck, and lack of ovarian function.

Edwards Syndrome (Trisomy 18)

A condition involving an extra copy of chromosome $18$ with a high rate of miscarriage and a $10\%$ survival rate past $1$ year.

Patau Syndrome (Trisomy 13)

A condition involving an extra copy of chromosome $13$ causing severe brain and spinal cord abnormalities; most do not survive past $10$ days.

X-Linked Chromosome Disorders

Disorders more common in males because they lack a second X chromosome to act as a "back up" for mutations inherited from the mother.

Red-Green Color Blindness

A vision deficiency caused by a mutation on the $X$ chromosome affecting opsin proteins in retinal cones; affects $1$ in $10$ males.

Hemophilia

A blood-clotting disorder caused by mutations in the $F8$ or $F9$ genes on the $X$ chromosome.

Fragile X

A condition caused by an $FRM1$ gene mutation that disrupts the $FMRP$ protein, leading to severe intellectual disability and physical features like large ears and a long neck.

Huntington’s Disease

A degenerative disorder caused by the $HTT$ gene on chromosome $4$ that typically appears in the $30s$ or $40s$ and causes the basal ganglia to die.

Phenylketonuria (PKU)

A disorder involving the $PAH$ gene on chromosome $12$ that prevents the processing of phenylalanine, requiring a "diet for life" to avoid brain damage.

Tay-Sachs Disease

A fatal disorder caused by a mutation in the $HEXA$ gene on chromosome $15$, leading to a toxic buildup of $GM2$ ganglioside in the brain.

Sickle Cell Anemia

A condition caused by a mutation in the $HBB$ gene on chromosome $11$ that misshapes red blood cells, which die prematurely in $10$ to $12$ days.

Cystic Fibrosis

A disorder caused by the $CFTR$ gene on chromosome $7$ that results in thick, sticky mucus buildup in the respiratory and digestive systems.

Genetic Counseling

A meeting with a practitioner prior to pregnancy to determine the probability of conceiving a child with a genetic disorder.

Amniocentesis

A prenatal test conducted between the $15th$ and $18th$ week that samples amniotic fluid to check for genetic abnormalities.

Chorionic Villus Sampling (CVS)

A prenatal test conducted between $9$ and $12$ weeks that takes tissue from the chorion to test for genetic disorders.

Noninvasive Prenatal Testing (NIPT)

A prenatal test conducted between $10$ and $22$ weeks that examines cell-free DNA from a mother's blood sample.