KS4 Biology

1. KS4 Biology Inherited Diseases

2. Contents Inherited Diseases Cysticfibrosis Sickle cell anaemia Huntington’s disease

3. What is cystic fibrosis? Cystic fibrosis is an inherited disease that affects many body organs, particularly the lungs and digestive system. The air passages in healthy lungs are coated with a constant flow of mucus, which traps and removes bacteria. In a person with cystic fibrosis, mucus is thicker than normal. This thick, sticky mucus can block the lungs and airways. How will this affect a person with cystic fibrosis?

4. What is cystic fibrosis? A person with cystic fibrosis has breathing difficulties. They are at risk of repeated chest infections which can lead to lung damage. People with cystic fibrosis need daily physiotherapy, which involves massage to help loosen the sticky mucus. Antibiotics help to treat and control lung infections and prevent lung damage.

5. What is cystic fibrosis? Treatment for the cystic fibrosis also includes special inhalants. In severe cases, a lung transplant operation is required. People with cystic fibrosis can have problems digesting food. Most take enzyme pills when they eat to supply missing enzymes and allow digestion.

6. Living with cystic fibrosis Over 7,500 people in the UK are affected by cystic fibrosis. Children born with cystic fibrosis do not have a normal life expectancy, although this is improving all the time.

7. How is cystic fibrosis inherited? cystic fibrosis allele = c = C normal allele Cystic fibrosis is caused by a recessive allele. What symbols could stand for the different forms of this gene? What alleles has a person with cystic fibrosis inherited? A person with cystic fibrosis has the genotype cc. They have inherited a cystic fibrosis gene from both parents. c c

8. How is cystic fibrosis inherited? How do you represent the genotype of a person who inherits one cystic fibrosisallele? c C Does a person with this genotype have cystic fibrosis? A heterozygous person (Cc) is called a carrier. They do nothave the disease but they do carry the cystic fibrosis allele which they might pass on to their children. In the UK, 2.3 million people carry the cystic fibrosis gene.

9. Cystic fibrosis inheritance activity 1

10. Cystic fibrosis inheritance activity 2

11. Contents Inherited Diseases Cystic fibrosis Sickle cell anaemia Huntington’s disease

12. What is sickle cell anaemia? Sickle cell anaemia is an inherited disease that affects red blood cells. Normal red blood cells contain haemoglobin, a protein that carries oxygen around the body. In sickle cell anaemia, red blood cells have abnormal haemoglobin. This distorts red blood cells to form curved, sickle shapes.

13. What is sickle cell anaemia? Normal red blood cells are shaped so that they move easily through blood vessels. This ensures that oxygen is delivered to the body. normal cells move freely Sickle-shaped red blood cells can get stuck in narrow blood vessels and cause blockages. Oxygen is prevented from getting to the body’s tissues and organs. This leads to severe pain and can cause permanent organ damage. sickle cells get stuck

14. What is sickle cell anaemia? Red blood cells normally have a lifetime of about 4 months. Sickle cells are fragile and only last for 10–20 days. The shorter lifetime of sickle cells reduces the number of red blood cells leading to anaemia. People with anaemia feel weak and tired. Children with sickle cell anaemia are able to lead normal lives but need regular medical attention. Treatment sometimes includes blood transfusions.

15. Who is affected by sickle cell anaemia? It is estimated that there are around 6,000 people affected by sickle cell disorders in Britain. Sickle cell anaemia mostly affects people of African descent, but people from India, the Mediterranean and Middle East are also affected.

16. What causes sickle cell anaemia? normal allele sickle cell allele = s = S Sickle cell anaemia is caused by a recessive allele. What symbols could stand for the different forms of this gene? What alleles has a person with sickle cell anaemia inherited? A person with sickle cell anaemiahas inherited two sickle cell alleles, one from each parent. s s

17. What causes sickle cell trait? What is the genotype of a person who has inherited one sickle cellallele? s S Does a person with this genotype have sickle cell anaemia? The sickle cell allele is recessive so this person does nothave the disease. They are a carrier of the sickle cell allele.

18. Sickle cell anaemia inheritance activity

19. Contents Inherited Diseases Cystic fibrosis Sickle cell anaemia Huntington’s disease

20. What is Huntington’s disease? Huntington’s disease is an inherited disease that affects the brain and central nervous system. The wide-ranging symptoms of this inherited condition usually develop in adults between the ages of 30 and 50 . Huntington’s disease causes damage to nerve cells in the areas of the brain involved in the control of movement, planning and motivation. How will this affect a person with Huntington’s disease?

21. What is Huntington’s disease? People with Huntington’s disease are affected by gradual physical, mental and emotional changes. • The early symptoms of Huntington’s • disease include: • mild tremor • clumsiness • lack of concentration • problems remembering things • depression • mood changes, sometimes including aggressive behaviour. People can have symptoms for several years before finding out they have Huntington’sdisease. Why can it take so long for this disease to be diagnosed?

22. What is Huntington’s disease? The physical, mental and emotional symptoms of Huntington’s disease become progressively worse. As the disease continues, people mayexperience involuntary movements, weight loss, speech problems and extensive memory loss. Eventually a person with Huntington’s disease needs complete nursing care. Currently there is no cure for Huntington’s disease. Medication is available to help treat some symptoms such as involuntary movements, depression and mood swings. Around 4,800 people in the UK have Huntington’s disease.

23. How is Huntington’s disease inherited? normal allele = H Huntington’s allele = h Huntington’s disease is caused by a dominant allele. What symbols could stand for the different forms of this gene? If someone inherits one Huntington’s diseaseallele will they develop the disease? The Huntington’s disease allele is dominant,so inheriting H h one allele from either parent will lead to this condition.

24. How is Huntington’s disease inherited? Huntington’s disease is caused by a dominant allele and can be passed on by one parent who has the disease. Anyone who inherits the Huntington’s allelewilldevelop the disease, usually between the ages of 30 and 50. People with the Huntington’s allelemay have had a family before realizing that they have inherited the disease. If one parent has the Huntington’sallele and the other is a non-carrier, what is the chance that their children will have Huntington’s disease?

25. Huntington’s disease inheritance activity