In this chapter of IBDP Biology, we will learn about the cause, effects and the treatment of some genetic diseases.

• It’s a genetic disease that affects exocrine glands and mucus secreting glands of the airway, gut, reproductive system and some sweat glands.
• Cystic fibrosis leads to production of thick sticky mucus with the following effects: Problems in respiratory and digestive system, Infertility, Production of salty sweat.
• Treatment: Physiotherapy, Diet and enzymes, Drug therapy transplant surgery, Infertility treatment, Gene therapy

• When it comes to IBDP Biology, it's caused by a recessive gene resulting from mutation.
• Carriers of Cystic Fibrosis are phenotypically normal but have the ability to pass the gene to their offspring

• It’s a condition in organisms in which natural melanin pigment if the skin, eye and hair do not form.
• A mutant allele prevents the formation of enzyme tyrosinase which is active in melanocytes (pigment forming cells). As a result, the reaction of making melanin cannot occur
• Albinism is usually inherited through a recessive allele.

Photo of an albinism patient

When it comes to IBDP Biology,

• It’s a disorder that affects the polypeptide chain of the heamoglobin molecule in blood.
• Heamoglobin contains 574 amino acids that are arranged in four polypeptide chains and are held together by sulphur bridges.
• Types of Polypeptide Chains: Alpha α polypeptide chain, Beta β  polypeptide chain
• Each polypeptide chain is then arranged around an iron containing haem group.

• It’s inherited from genes on two loci on chromosome 16
• It’s caused by deletion of one or more genes
• The more genes are deleted; less alpha hemoglobin is formed resulting to more fatal condition.
• Individual with mild thalassemia tend to have low levels of anemia and increased resistance to malaria

• When it comes to IBDP Biology, its caused by mutation in HBB gene on chromosome 11.
• About 100 types of mutation affect the gene and their effects differ.
• Many mutations may reduce the number of beta heamoglobin chain leading to mild symptoms of anemia.
• Severe beta thalassemia could occur especially when heamoglobin molecule cannot be made. This condition is called thalassemia Major of Cooley’s anemia
• Mutation that cause beta thalassemia usually form recessive alleles. Carrier parents have the ability to produce sick children.

This is the end of this topic

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