Warm ups:
1. What is a mutation?
2. Can you inherit mutations from your
parents?
Human genetics
Genes and Health
1. Sometimes, genes undergo mutations
that can be harmful and cause disorders
or diseases.
2. Sickle cell anemia, cystic fibrosis and
down syndrome are examples of
disorders that result from mutations
Recessive genetic disorders
1. Recessive disorders – the disorder is a
recessive gene
a. If you have one gene – you are a carrier (you carry
the gene but you don’t have the actual disease)
b. If you have both recessive genes – you will have the
disorder
2. Sickle cell disease – blood cells are sickle
shape (half moon) instead of round
a. Can’t carry oxygen correctly
b. Need blood transfusions
3. Cystic Fibrosis – body produces more
mucus in lungs and digestive tract
a. Hard to breath and causes lung damage
b. Digestive tract problems
c. Helped with antibodies and physical therapy
to break up the thick mucus
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.
r
Rr
Father = _____
rr
Mother = ____
R
Rr
Rr
r
r r
r r
50
____ % carrier
50
____ % have sickle cell
anemia
50 % homozygous
____
50 % heterozygous
____
r
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.
R
r
Father = R
_____
RR
Mother = ____
R
RR
RR
r
Rr
Rr
50
____ % carrier
0
____ % have sickle cell
anemia
100 % no disease
____
50 % homozygous
____
50
____ % heterozygous
R
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)
C
C
c
Father = _____
C
c
Mother = ____
50
____ % carrier
25
____ % have cystic fibrosis
75
____ % no disease
50
____ % homozygous
50
____ % heterozygous
c
C CC C c
c
Cc
cc
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)
c
Father = C
_____
cc
Mother = ____
50
____ % carrier
50
____ % have cystic fibrosis
50
____ % no disease
50
____ % homozygous
50
____ % heterozygous
c
C Cc
c
c c
c
Cc
cc
Sex Determination
1. Last pair of chromosomes determine the
sex of a person
2. “X” = female chromosome, “Y” = 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?
Complete a
punnett square to see how this will affect their offspring.
(X = female , y = male)
Xy
Father = _____
XX
Mother = ____
50
____ % female
50
____ % male
X
X
X
XX XX
y
Xy
Xy
Exit slip questions
1. Explain the difference between being a
carrier of a disease and actually having
the disease.
2. If both parents are carriers for cystic
fibrosis, what percent of children will also
be carriers?