Hereditary Influences

A set of Q&A flashcards covering key concepts from the lecture notes on hereditary influences.

What is genotype?

The genes that one inherits.

What is phenotype?

The observable or measurable characteristics of an organism.

What is conception?

The moment when an ovum released by a woman’s ovary is fertilized by a man’s sperm.

What is the difference between genotype and phenotype?

Genotype is the genetic makeup; phenotype is the observable traits resulting from genotype and environment.

How many chromosomes are in a human zygote?

46 chromosomes.

What are chromosomes?

Threadlike bodies in the nucleus that contain genes.

What are genes?

Segments of DNA that are the basic units of heredity and code for proteins.

What is DNA?

A double-helix molecule that provides the chemical basis for development.

What is a zygote?

The fertilized cell formed when sperm fertilizes an ovum.

What is mitosis?

Cell division that produces two identical daughter cells, duplicating chromosome sets.

What are germ cells?

Cells in the gonads that produce sperm and ova through meiosis.

What is meiosis?

The cell division that produces haploid gametes and includes crossing-over.

How many chromosomes do gametes contain?

23 chromosomes.

What is crossing-over?

Exchange of genetic material between paired chromosomes, creating new combinations.

What is independent assortment?

Chromosome pairs segregate independently, producing many genetic combinations (about 2^23 in humans).

What are monozygotic twins?

Identical twins from a single zygote with identical genes.

What are dizygotic twins?

Fraternal twins from two separate ova fertilized by two different sperm.

How is sex determined in humans?

By the 23rd chromosome pair: males are XY and females are XX; the father determines sex by providing X or Y.

What are autosomes?

The first 22 pairs of chromosomes that are similar in males and females.

What are sex chromosomes?

The 23rd pair of chromosomes (X and Y).

What do genes do at a biochemical level?

They code for amino acids that form enzymes and proteins, regulate differentiation, and interact with the environment.

What are the basic patterns of gene expression mentioned?

Simple dominant-recessive inheritance, codominance, and sex-linked inheritance.

What is congenital defect?

A condition present at birth, many of which are not detectable at birth.

What are chromosomal abnormalities?

Abnormal distribution of chromosomes during meiosis; many are lethal.

What is amniocentesis?

A prenatal test that withdraws amniotic fluid with a needle for testing.

What is chorionic villus sampling (CVS)?

A prenatal test that collects placental tissue for testing, performed in the 8th–9th week.

What is ultrasound (sonography) used for in pregnancy?

A prenatal diagnostic technique using sound waves to scan the womb, useful after about 14 weeks.

What is Turner’s syndrome?

XO; missing an X chromosome in females, with features such as short stature and underdeveloped ovaries.

What is Triple X syndrome?

XXX; females with an extra X chromosome, often taller and may have mild learning difficulties.

What is Klinefelter syndrome?

XXY; males with tall stature, reduced facial/body hair, small testes, possible breast tissue."

What is Jacobs (Jacob’s) syndrome?

XYY; males with tall stature and possible behavioral problems.

What is cystic fibrosis?

A genetic disease causing thick mucus buildup in lungs, pancreas, and other organs.

What is diabetes?

A condition with high blood sugar due to insufficient insulin production or insulin resistance.

What is Duchenne muscular dystrophy?

A progressive muscle-weakening genetic disease, mostly affecting boys; no cure.

What is hemophilia?

A rare inherited bleeding disorder with reduced blood clotting.

What is phenylketonuria (PKU)?

A genetic disorder due to lack of the enzyme that breaks down phenylalanine, causing buildup.

What is sickle-cell anemia?

A genetic mutation causing sickle-shaped red blood cells and anemia.

What is Tay-Sachs disease?

A genetic disorder causing progressive nerve cell death in the brain and spinal cord.

What is genetic counseling?

A service to assess the likelihood of hereditary disorders by collecting family history (pedigrees).

What is prenatal screening?

Tests such as amniocentesis, CVS, and ultrasound to detect chromosomal/genetic issues, especially in older pregnancies.

What is a pedigree?

A family history used to estimate the risk of hereditary disorders.