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Flashcards in Lecture 9 Deck (17)

Which chromosome encodes the alpha globin molecule?

Chromosome 16


Which chromosome encodes the beta globin molecule?

Chromosome 11


Differences in hemoglobin subgroups for class A, A2, and F?

HbA contains two alpha and two beta subunits. HbA2 contains two alpha and two delta subunits. HbF contains two alpha and two gamma subunits.


What condition do alpha and beta thalassemia induce?

Microcytic anemia - red blood cells are smaller in size than average


Difference between HbS and HbC?

HbS is produced by a glutamate to valine change in the 6th codon coding for hemoglobin. HbC is produced by a glutamate to lysine change in the 6th codon coding for hemoglobin.


What is alpha thalassemia most often caused by?

Since chromosome 16 has two alpha globin genes on each chromosome, this predisposes this region of the chromosome to frequent deletion events by unequal crossing over. Hence, alpha thalassemia is most often caused by loss of alpha globin genes by deletion


What is an inclusion body?

An inclusion body is a protein containing viral proteins that can infect a host cell


What causes Beta thalassemia?

An alpha chain inclusion body forms in erythroid precursor cell in the bone marrow causing production of inefficient alpha subunits in hemoglobin. The inclusion body causes point mutations on the beta globin gene on chromosome 11


Difference between B0 and B+?

B0 is a mutant allele for the hemoglobin beta subunit in which no functional B-globin is made (nonsense mutation). B+ is a mutant allele for the hemoglobin beta subunit in which some partially functional B-globin is made (missense mutation)


What does hematocrit measure?

Hematocrit measures the % of RBCs in the blood (use centrifugation)


What is a reticulocyte count?

Measure of new RBCs that have been formed


How long do RBCs live on average?

120 days


How long does it take a RBC to circulate around the entire body?

About 1-3 minutes depending on the speed of the heart beating


What is a common characteristic of hemoglobinopathies?

They are usually caused by point mutations


What is unique about a point mutation found in thalassemia?

The point mutation does not code for a new protein subunit in hemoglobin, but rather creates a less functional protein of the same identity. This causes an imbalance in the # of normal alpha chains to beta chains


What is Bart's Hemoglobin?

4 gamma chains caused by a mutation in alpha globin gene. Causes extremely high affinity for oxygen and cant release oxygen


What are the three hemoglobin structure variants?

Hemolytic anemia, thalassemia, & altered oxygen transport (increased/decreased transport or irreversible binding)