powerpoint about inherited diseases

1. Inherited diseases
Starter: What
diseases are these?
Friday, 11 December 2020
Key words: Dominant, Recessive, allele

2. The big picture: “What
diseases can be inherited?”
Learning outcomes
 State some of the symptoms of genetic
diseases.
 Construct and interpret punnet squares
to show the likelihood of these alleles
being passed on.
 Evaluate the impact of these diseases on
a person’s life.

3. Success criteria
• Describe the symptoms of cystic fibrosis,
polydactyly and Huntington’s disorder
• Explain how the diseases are inherited
• Predict how the alleles can be inherited

4. Reminder…
•Dominant allele - an allele that controls the
development of a
characteristic when it is
present on only one of the
chromosomes.
•Recessive allele - an allele that controls the
development of a
characteristic only if the
dominant allele is not present

5. Cystic fibrosis:
recessive gene
Polydactyly:
dominant gene
Extra challenge: Which of the two alleles (cystic fibrosis and polydactyl) would
spread faster in a population? Explain your reasons
Huntington's disease:
dominant gene

6. • https://www.youtube.com/watch?v=FMA
OEOmLoUE
1.What are the symptoms of cystic fibrosis?
2.What causes cystic fibrosis?
3.Draw a genetic diagram to give the possible offspring
of 2 carriers of cystic fibrosis (Ff)
Extra challenge: Explain why (using a punnet square) it is
impossible to suffer from cystic fibrosis if only one of
your parents is a carrier.
Cystic fibrosis

7. Cystic fibrosis
• Affects about 1 in 1600 people in the UK
• A disorder of cell membranes
• Caused by a defective gene inherited from
parents
• Lungs produce a thick mucus that has to be
removed by massage. This causes blockages in
the air passages and chest infections
• Mucus also occurs in pancreas which causes
digestive problems

8. Genetics of Cystic Fibrosis
F f
F FF
normal
Ff
carrier
f Ff
carrier
ff
sufferer

9. The likelihood is…
• If two parents who
are both cystic
fibrosis carriers
have a child what
chance is their that
they will have a
cystic fibrosis child?
• 25%. The child will
need to inherit 2
recessive cystic
fibrosis genes (ff)

10. Question
• If only one parent is
a cystic fibrosis
carrier can they
have a child who is a
cystic fibrosis
sufferer?
• No – because the
cystic fibrosis allele
is recessive the
child needs to
inherit 1 from each
parent

11. Cystic fibrosis is an example of an inherited disease caused by gene
mutation, which affects about one child in 2000.
a) Which parts of the body are mainly affected by this condition?
.......................................................................................................................................
........... (2 grades)
b) What substance (produced in excess) affects these parts of the
body? ................................... (1 grades)
c) The reproductive system is also affected by this condition. As a
result, people suffering from cystic fibrosis are often ………………….. (1
grades)
d) What are the main treatments for cystic fibrosis?
……………………………. and …………………………... (2 grades)
e) What genotype does a cystic fibrosis sufferer have? (1 grades)
f) Draw a genetic diagram to show how two healthy parents can have a
child affects by cystic fibrosis (4 grades)
11/11 – A*, 10/11 = A, 7/11 = B 5/11 = C, 3/11 = D 2/11 = E

12. Polydactyly
Polydactyly is a genetic
disorder of the
seventh chromosome
which results in extra
fingers or toes.
Polydactyly actually
means “Extra Digits.”

13. You only need to get the
abnormal gene from one
parent in order to
inherit the disease. One
of the parents may
often have the disease.
A Dominant allele

14. Probability of Disease occurring
G g
G
g
Complete the Punnet square to
show the probability of having
polydactyl if both your parents do.
Extra challenge:
If Mark (who is heterozygous dominant for
polydactyl) has a child with Vanessa (who does
not have polydactyl) what is the chance of
their child having it? Use a Punnet square in
your answer.

15. • https://www.youtube.com/watch?v=4Hg
FUvVyHYQ
1.Describe some symptoms of Huntington's disease
2.What causes Huntington's disease?
3.Most dominant allele diseases are removed by natural
selection. Why do you think Huntington's is different
Huntingtons

16. Nerve cells in brain degenerate.
Very rare but very serious.
Incurable and fatal.
Huntington’s

17. H h
h
h
Hh hh
Hh hh
Probability
of a child
with
Huntington’s
50% (Hh)
The allele for Huntington’s disease is
dominant.

18. Draw a Punnett square and calculate the percentage of
sufferers, carriers (if any) and unaffected offspring
for the following parents.
1.Dad suffers from Huntington’s but mum does
not.
2.Dad suffers from Huntington’s as does mum.
3.Dad is a carrier of CF but mum is not.
4.Dad has CF, so does mum.

19. Complete the worksheet

20. Exam style questions

21. Exam style questions

22. Plenary
1) Frankie and Annie are planning a family. Frankie's
sister has cystic fibrosis, and tests have shown that
he is a carrier. Annie has had tests too, and she is not
a carrier of the faulty gene. Produce a genetic
diagram to show the chance of Annie and Frankie
having a child affected by cystic fibrosis.
2) Manx cats are born with no tail. If a Manx cat is
mated to a normal cat, half the litter will have tails
and half will not. This suggests that Manx cats are
heterozygous for a dominant gene T which causes no
tail to form, with the normal tail gene t being
recessive. Show the Manx cat cross described above.

23. Genetics of Cystic Fibrosis –
Question 1
F F
F FF
normal
FF
normal
f Ff
carrier
Ff
carrier
0%
chance
of child
with CF

24. Genetics of Manx cat – Question 2
T t
t Tt tt
t Tt tt
Tt –
Manx no
tail
Tt –
normal
cat