Human Genetics

Question 1

Mandela inheritance- Dominant & Recessive traits

Answer 1

Dominant-
shows up even if just one copy of gene (e.g., brown eyes)

Recessive -two copies of the gene are present

Question 2

Mandela inheritance 3 key laws
1. Law of segregation
2.law of independent
3. Law of dominance

Answer 2

1. Law of Segregation - You get one gene from each parent. (e.g., Bb = brown eyes, b from mum, B from dad)
2. Law of Independent Assortment
   • Genes for different traits are inherited separately (e.g., eye color and height don’t affect each other)
3. Law of Dominance-Dominant allele masks recessive

Question 3

Genetic variation;Genetic disorder-
PKU- Phenylketonuria

Answer 3

Can’t break down phenylalanine (an amino acid)

Causes brain damage if untreated

Tested at birth

PKU = Protein Killer Untreated

Question 4

Genetic variation;Genetic disorder-
Sickle cell

Answer 4

Red blood cells shaped like sickles

Causes pain and poor oxygen flow

Common in people of African descent

Sickle = S-Shaped cells = Suffering cells

Question 5

Genetic variation;Genetic disorder- cystic fibrosis

Answer 5

Thick mucus in lungs/digestive system

Breathing + digestion issues

CF = Coughing Forever

Question 6

Genetic variation;Genetic disorder-
Huntington’s chorea

Answer 6

Brain disorder, affects movement & memory

Dominant = only one copy needed

Appears later in life (30s-50s)

Remember- Hunting-twitch = movement disorder

Question 7

Chromosomal disorders

Answer 7

Extra chromosome 21 (Trisomy 21)

Learning difficulties, distinctive appearance

Risk increases with mother’s age

Question 8

Diagnostic testing (before birth)

Amniocentesis

Answer 8

Done at 15–20 weeks

Needle takes amniotic fluid (has baby’s cells)

Tests for genetic/chromosome problems

Amino- comes later

Question 9

Diagnostic testing (before birth)
Chorionic Villus Sampling (CVS)

Answer 9

Done earlier: 10–13 weeks

Takes cells from placenta

Slightly higher risk than amniocentesis

CVS: Comes early