Chapter 3 - Genetics

Gene

fundamental unit of DNA

Human Karyotype

- picture of chromosome pairs

- 23 pairs of chromosomes (46 total)

- can identify chromosomal abnormalities

Autosomes

first 22 pairs of chromosomes

Sex Chromosome

- 23rd pair of chromosomes

- XX: female

- XY: male

Epigenetic Changes

- alterations in gene expression due to environmental stressors, behaviors, or lifestyle

- doesn't change the DNA sequence but rather the way DNA is "read" (turns genes on or off)

Examples of Epigenetic Changes

smoking, diet, exercise

Familial Hypercholesterolemia - Inheritance Pattern

autosomal dominant

Familial Hypercholesterolemia - Characteristics

- lack of LDL receptors (LDL "bad cholesterol" then accumulates in the blood)

- elevated cholesterol

- atherosclerosis (hardening of arteries)

Familial Hypercholesterolemia - Results

extremely high levels of blood cholesterol which increases the chance of a heart attack (with children also at risk)

Tay-Sachs Disease - Inheritance Pattern

autosomal recessive

Tay-Sachs Disease - Signs/Symptoms

- cherry-red spot in the retina

- muscle flaccidity

- fatigue

Tay-Sachs Disease - Characteristics

- lysosomal storage disease

- deficient in hex A enzyme leads to the accumulation of gangliosides in the brain

- prominent in ashkenazi jews

Tay-Sachs Disease - Results

death normally occurs by age 3

Huntington's Disease - Inheritance Pattern

autosomal dominant

Huntington's Disease - Characteristics

- movement disorder (ticks)

- cognitive disorder (slurred speech)

- behavior disorder (mood swings)

Huntington's Disease - Adult Onset (40+)

- most common type

- huntingtin protein (HTT) disrupted by trinucleotide (CAG) repeats

Huntington's Disease - Early Onset

less common than adult onset

Huntington's Disease - Treatment

none