Human genetics
Student note sheet
Genes and Health:
1. Sometimes, genes undergo __________ that can be harmful and cause ______________ or
______________.
2. Sickle cell anemia, cystic fibrosis and down syndrome are examples of ___________ that result from
____________.
Recessive genetic disorders:
1. Recessive disorders – the disorder is on a ______________ gene
- If you have one gene – you are a ____________ (you carry the gene but you don’t have
the actual disease)
- If you have both recessive genes – you will _________ the disorder
2. Sickle cell disease – blood cells are _________ shape (half-moon) instead of ________
- Can’t carry __________ correctly
- Need blood transfusions
3. Cystic Fibrosis – body produces more _________ in lungs and digestive tract
- Hard to ___________ and causes lung damage
- Digestive tract problems
- Helped with antibodies and physical therapy to
break up the thick mucus
Practice Punnett square problems:
1. A father is a carrier of sickle cell disease and the mother has the disease. (R = round blood cells, r =
sickle shaped blood cells) Complete a Punnett square to determine the offspring of these parents.
Father = _____
Mother = ____
____ % carrier
____ % have sickle cell anemia
____ % homozygous
____ % heterozygous
2. A father is the carrier of the gene for sickle cell anemia but the mother is purebred for normal red
blood cells. (R = round blood cells, r = sickle shaped blood cells) Complete a punnett square to
determine the offspring of these parents.
Father = _____
Mother = ____
____ % carrier
____ % have sickle cell anemia
____ % no disease
____ % homozygous
____ % heterozygous
3. A father and mother both carry the gene for cystic fibrosis. Complete a punnett square to see how this
will affect their offspring. (C = normal , c = cystic fibrosis)
Father = _____
Mother = ____
____ % carrier
____ % have cystic fibrosis
____ % no disease
____ % homozygous
____ % heterozygous
4. A mother has cystic fibrosis and marries a man who is a carrier of the disease. Complete a punnett
square to see how this will affect their offspring. (C = normal , c = cystic fibrosis)
Father = _____
Mother = ____
____ % carrier
____ % homozygous
____ % heterozygous
____ % no disease
____ % have cystic fibrosis
Sex Determination:
1. Last pair of _____________ determine the sex of a person
2. “____” = female chromosome, “___” = male chromosome
3. XX = female sex, XY = male sex
A man and women get married and have children. What are their chances of having a boy?
punnett square to see how this will affect their offspring. (X = female , y = male)
Father = _____
Mother = ____
____ % female
____ % male
Complete a