[BCH210H1] - Final Exam Guide - Comprehensive Notes for the exam (40 pages long!)

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magentarhinoceros129

29 Nov 2016

School

UTSG

Department

Biochemistry

Course

BCH210H1

Professor

Stavroula Andreopoulos

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BCH210H1 Full Course Notes

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Complex molecules like proteins are built from simple building blocks like amino acids. Biochemistry allows us to understand the molecular basis of life and disease. The most commonly asked question is why are they red? : the calls contain massive amounts of hemoglobin, hemoglobin is a protein. Is a tetramer consisting of two alpha and two beta polypeptide chains. Contains heme which gives the colour. Globin is a protein which is colourless by natural. A single amino acid change (glu6val) in the beta-chain of haemoglobin causes sickle cell anemia we must learn more about this amino acid. Hb s forms long polymers that change the shape of the red blood cell from a disk to a sickle shape. Polymers of amino acids linked in series by peptide bonds: linear chain/array. Fold into specific 3d structures: linear sequence determines the folding of 3d structure (even a single change) Agents of biological function, often enzymes catalysts.

Related Questions

Normal adult hemoglobin is called Hemoglobin A (Hb A). Ninety-eight percent of adult hemoglobin is Hb A and 2% is Hb A2. There are other forms of hemoglobin. For example, the developing fetus has a different kind of hemoglobin than most normal adults. Fetal hemoglobin (Hb F) is synthesized beginning at the third month of gestation and continues up through birth. After the neonate is born, hemoglobin F synthesis declines (because synthesis of the (chain declines) and hemoglobin A is synthesized. By the time the baby is six months old, 98% of its hemoglobin is Hemoglobin A. There is also a mutant form of hemoglobin called Hemoglobin S, which is found in persons with the disease sickle cell anemia. The disease sickle cell anemia is one of the major health problems facing the African-American community. The World Health Organization estimates that 250,000 babies world wide are born with sickle cell anemia. Currently there is no cure. A person afflicted with sickle cell anemia has inherited a defective gene from each parent. The defective gene is the one coding for the Î²-chain. The amino acid at position 6 on each Î² chain has been mutated from a glutamate to a valine. Normal Î± chains have a decreased affinity for the mutated Î² chains; thus assembly of the HbS tetramer is more difficult. Red blood cells containing HbS form a sickle shape because the Hb S molecules polymerize. Hb S molecules are more likely to polymerize when in the deoxygenated T form than in the oxygenated R form. The polymerized Hb deforms the normal discoid shape of the red blood cells, producing a sickle-shaped cell. The sickle shaped red blood cells become trapped in capillaries and organs, depriving the victim of adequate oxygen supply and causing chronic pain and organ damage.

Glover, R. E., Ivy, E. D., Orringer, E. P., Maeda, H., and Mason, R. (1999) Molecular Pharmacology 55, pp. 1006-1010.

Huang, J., Hadimani, S. B., Rupon, J. W., Ballas, S. K., Kim-Shapiro, D. B., and S. Bruce King (2002) Biochemistry 41, pp. 2466-2474.

S. Bruce King (2003) J.Clin. Invest., 111, pp. 171-172.

1) Why do you think Hb S has higher tendency to polymerize compared to Hb A?

A human gene called the Î²-globin gene encodes a polypeptide that functions as a subunit of the protein known as hemoglobin. Hemoglobin is found within red blood cells; it carries oxygen. In human populations the Î²-globin gene can be found as the common allele known as Hb^A, and it can also be as the Hb^S allele. Individuals who have two copies of the Hb^S allele have the disease called sickle cell disease. Are the following examples descriptions of genetics at the molecular, cellular, organism, or population level?

A. The Hb^Sallele encodes a polypeptide that functions slightly differently from the polypeptide encoded by the Hb^Aallele.

B. If an individual has two copies of the Hb^Sallele, that persons red blood cells take on a sickle cell shape.

C. Individuals who have two copies of the Hb^Aallele do not have sickle cell disease, but are not resistant to malaria. People who have one Hb^Aallele and one Hb^S allele do not have sickle cell disease but are resistant to malaria. People who have two copies of the Hb^Sallele have sickle cell disease, and this disease may significantly shorten their lives.

D. Individuals with sickle cell disease have anemia because their red blood cells are easily destroyed by the body.

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16. Sickle cell anemia is a genetic disorder resulting in an alternation of the structure and function of hemoglobin. Specifically, the amino acid valine replaces glutamate in a position located in the surface of the protein. Based on your knowledge of protein sequence answer the following:

a. At what level of protein structure does the amino acid substitution occur? Explain?

b. Provide a biochemical rationale for why this change in the sequence of hemoglobinâs beta chain results in red blood cells sickling. Your answer should include reference to structures of valine and glutamine shown above.

[BCH210H1] - Final Exam Guide - Comprehensive Notes for the exam (40 pages long!)

BCH210H1 Full Course Notes

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