1. 14-19 Learning Core Development Programme Laura Blacoe Connah’s Quay High School

2. Aim To help pupils understand more about the importance of the increasing knowledge of genetics and how and why people inherit genetic disorders.

3. Lesson Objectives We are learning:  That genetic information is found in the nucleus of every cell in the body and determines characteristics.  That genetic information is inherited from parents and that in each pair of chromosomes one is inherited from the mother and one from the father.  That diseases and disorders can be inherited.

4. Lesson Outcomes What I am looking for: TYC describe what DNA, genes and chromosomes are and how they determine characteristics. TYC describe how genetic information is inherited and use genetic cross diagrams to determine the possible genotype of offspring. TYC describe the symptoms of 4 different genetic diseases and explain how they are inherited. Also, predict possible genotype of offspring using genetic cross diagrams.

5. Sexual Fertilisation

6. Zygote Embryo Foetus

7. Human Chromosomes

8. Using letters to represent alleles Dominant alleles = Capital letter Recessive alleles = Lower case letter of the dominant allele Black hair allele = B Red hair allele = b

9. Genetic Crosses B b B B BB Bb Black Hair

10. B b b B BB Bb bb Bb Mum’s Genotype Dad’s Genotype

11. Activity 1 – Huntington’s Disease Huntington’s disease is a fatal disease that affects the nervous system. It is caused by a defective allele on chromosome 4. It affects both men and women and makes the body shake uncontrollably. Faulty allele = H Normal allele = h

12. Answers to activity 1 H h h h Hh hh Hh

13. Extension Activity John and Karen have both discovered that they have the genetic disorder Huntington’s disease. But, they already have 2 children together. Explain to them (using genetic cross diagrams) the possibilities of their children’s genotype.

14. Answers to extension activity H H HH HH H h H H Hh HH HhHH Hh H h hhHh

15. Activity 2 – Cystic Fibrosis Cystic Fibrosis is a genetic disorder caused by a recessive faulty allele. C = Normal allele c = Faulty allele Cystic Fibrosis affects the cells membranes and causes the production of excess mucus in the respiratory organs and digestive system.

16. C c C c Cc

17. Activity 3 – Sickle Cell Anaemia

18. Distribution of Sickle Cell sufferers

20. S s S s SSSsSs SsSs ss

21. Activity 4 - Haemophilia Symptoms:  Main symptom is that blood does not clot properly.  Even small cuts and tooth extractions can be lethal due to blood loss.  Small knocks can cause internal bleeding and big bruises and joints may also bleed.

22. Treatment  The condition can be treated quite successfully by regular injections of the clotting factor – FACTOR 8.

23. Haemophilia – The sex-linked Gene Sex linked means only present in males or females. Haemophilia is only present in males. Sex-linked conditions occur when the there’s a defective allelle on the X- chromosome. Any recessive genes on the man’s X- chromosome will express themselves because their equivalent gene is missing form the shorter Y-chromosome.

24. There are 5 possible combinations for the blood clotting allele Normal MaleXHYXHY Haemophiliac Male XhYXhY Normal FemaleXHXHXHXH Carrier FemaleXHXhXHXh Zygote does not develop XhXhXhXh You can’t have a male carrier without them having the disease. There are no female sufferers because the offspring don’t develop. H = Normal h = Haemophiliac

25. XHYXHY XHXhXHXh XHXH Y XHXH XhXh XHXhXHXh XHXHXHXH X H Y X h Y Parent Genotypes Normal Female Carrier Female Normal Male Haemophiliac Male Genetic Cross Diagram for Haemophilia