Hemoglobinopathies

Question 1

hemoglobin A

Answer 1

alpha 2 beta 2, predominant form of Hb found on RBC

Question 2

hemoglobin A2

Answer 2

alpha 2 delta 2

Question 3

hemoglobin F

Answer 3

alpha 2 gamma 2, fetal hemoglobin

Question 4

hemoglobin variants

Answer 4

result of single amino acid substitutions in one of the globin polypeptide chains

Question 5

methemoglobin

Answer 5

ineffective oxygen carrier, can result in person having cyanosis (blue skin), generator by heme oxidation, does not bind to oxygen well

Question 6

HbS

Answer 6

sickle cell anemia, single substitution from Glu to Val at position 6 of the beta chain, results in HbS to aggregate and polymerize into rigid extended fibers

homozygotes suffer from sickle cell anemia whereas heterozygotes live normal lives with protection from malaria.

Question 7

HbC

Answer 7

alpha 2 beta 2. Glu to Lys at position 6 of the beta chain. does not polymerize like HbS but does protect against malaria

Question 8

HbH

Answer 8

Beta 4. binds oxygen very tightly and non-cooperatively

Question 9

HbBarts

Answer 9

gamma 4. binds oxygen very tightly and non-cooperatively

Question 10

detection of abnormal Hb

Answer 10

native gel electrophoresis, HbS is less negatively charged than HbA resulting in slower migration

Question 11

amin acid substitutions can result in

Answer 11

changes in surface residues, changes in internal residues, heme oxidation leads to methemoglobin