Huntington's and Polydactyly Disease

L/O: To understand how genetic inheritance of

Huntington's and polydactyly occurs

Starter Recap: If a mother is a carrier and a father has cystic fibrosis, draw out the

chances of having the conditions

CORE: Effective Participators

Success Criteria:C – State what Huntington's and polydactyly are B – Describe the symptoms of Huntington's and polydactyly and how they occurA – Explain the genetic basis for Huntington's and polydactylyA* - Predict the likelihood of inheritance of Huntington's and polydactyly

KEY WORDSHuntingtons genes

recessivedominant expressed

polydactyly

Huntington's Chorea

Huntington’s Disease = genetic disorder of the nervous system

http://www.youtube.com/watch?v=d71Pjv2sPfc&feature=related

What symptoms might this cause?

Look at the questions and answer these as you watch

Huntington’s Disease

Huntington’s Genetics

How does Huntington’s continue throughout generations?

Quick check…

1.What type of disease is Huntington’s disease?

2.What are some of the external symptoms of Huntington's disease?

3.Who is affected by huntington’s disease?

4.What chromosome is affected in Huntington’s disease?

5.What are the internal symptoms?

How do you inherit Huntington’s?

Huntington’s genes are dominant, so you only need one parent to have it to inherit the

conditionAllele for Huntington's = HNormal Allele = hComplete the genetic cross for the following three situations:a)Both parents have the disorder in both allelesb)One parent has the condition and the other does

not

Dominant = stronger gene that is expressed

How do you think the disease comes to be passed on?

Polydactyly

Polydactyly = genetic disorder where babies are born with extra fingers or toes

The inheritance sequence is the same as for Huntington’s as it is a dominant disorder

Complete the genetic cross for the following two situations:a)Both parents have the

disorder in both allelesb)One parent has the

condition and the other does not

Sickle Cell Anaemia

• Caused by a recessive allele (s)• Causes red blood cells to change

shape – can be trapped in blood vessels & anaemia

Sickle Cell Anaemia

• Symptoms:- Breathlessness- Lack of energy- Tired- Affected children fail to grow- Pain and death of tissue- Block blood vessels

Sickle Cell Anaemia

• What is the advantage of being heterozygous for sickle cell anaemia in certain regions?

DimplesThe allele for dimples (D) is

dominant over the allele for no-dimples (d).

D ddd

Dd ddDd dd

Probability of a child with dimples50%

AlbinismThe allele for normal

melanin (M) is dominant over the allele for albinism

(m).

M mMm

MMMmMmmm

Probability of a child with albinism25%

Fact Page on Huntington’s or polydactyly for a doctors surgery

Success Criteria:C – State what Huntington's and polydactyly are B – Describe the symptoms of Huntington's and polydactyly and how they occurA – Explain the genetic basis for Huntington's and polydactylyA* - Predict the likelihood of inheritance of Huntington's and polydactyly

Huntington’s genes are dominant, so you only need one parent to have it to inherit the

condition

Apply your knowledge…

Complete the examination question to check your understanding of the disease.

Success Criteria:C – State what Huntington's and polydactyly are B – Describe the symptoms of Huntington's and polydactyly and how they occurA – Explain the genetic basis for Huntington's and polydactylyA* - Predict the likelihood of inheritance of Huntington's and polydactyly