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 occur A – Explain the genetic basis for Huntington's and polydactyly A* - Predict the likelihood of inheritance of Huntington's and polydactyly KEY WORDS Huntingtonsgenes recessive dominant expressed polydactyly

Huntington's Chorea Huntington’s Disease = genetic disorder of the nervous system 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 condition Allele for Huntington's = H Normal Allele = h Complete the genetic cross for the following three situations: a)Both parents have the disorder in both alleles b)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 alleles b)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?

Dimples The allele for dimples (D) is dominant over the allele for no- dimples (d). D d d d Dd dd Dd dd Probability of a child with dimples 50%

Albinism The allele for normal melanin (M) is dominant over the allele for albinism (m). Mm M m MM Mm mm Probability of a child with albinism 25%

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 occur A – Explain the genetic basis for Huntington's and polydactyly A* - 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 occur A – Explain the genetic basis for Huntington's and polydactyly A* - Predict the likelihood of inheritance of Huntington's and polydactyly