Flashcards in Normal and abnormal hemoglobin Deck (16)
myoglobin binds oxygen best at what concentration?
low oxygen concentration
which Hb subunits bind oxygen first?
how does 2,3-BPG affect oxygen affinity?
lowers oxygen affinity (stabilizes T form)
how does Hb F differ from Hb A and what is the significance?
1. Hb F has a histidine residue in the beta chain - 2,3-BPG cannot bind as well
2. Hb F oxygen affinity increases - allows oxygen flow from mother to fetus
what are the two types of hemoglobinopathies?
1. structural variants
which Hb variant causes sickle cell disease? what is the result?
1. Hb S
2. deoxygenated Hb polymerizes
3. misshapen cells block circulation
definition: sickle cell trait, sickle cell disease
1. trait - heterozygous for Hb S
2. disease - homozygous for Hb S
how does hydroxyurea treat sickle cell disease?
increases Hb F
Hb C causes what condition? why?
1. hemolytic anemia
2. less soluble than Hb A - precipitates and breaks
Hb E leads to what conditions? why?
1. mild thalassemia, microcytosis, hypochromia, mild anemia
2. mutant B globin chain is not synthesized effectively
reduced synthesis of either type of chain reduces amount of functional tetramer formed
when do alpha thalassemias manifest?
throughout development and all of life
how are alpha thalassemias most often generated?
deletion by homologous recombination - misalignment during meiosis because loci look similar
1 functional B globin gene / 1 defective B globin gene will cause what symptoms?
1. low MCV
2. low MCH
3. increased Hb A2
the best characterized beta thalassemias are caused by what defect?
splicing leading to point mutation