Q: Which of the following equations correctly represents the percentage of total globin synthesis for a given globin type over time?

$$\frac{\text{Globin type synthesis}}{\text{Total globin synthesis}} \times 100$$

Question 1

Which of the following best explains why a single amino acid substitution in the β-globin subunit leads to sickle cell anemia?

Accepted Answer

It results in hydrophobic interactions between hemoglobin molecules, leading to their aggregation.

Question 2

Which hemoglobin type is predominant during fetal development, and what is its chain composition?

Accepted Answer

Hemoglobin F; two alpha and two gamma chains

Question 3

A patient with sickle cell anemia has a mutation in the β-globin gene. Which chromosome contains the β-globin gene?

Accepted Answer

Chromosome 11

Question 4

Why does the sickle cell allele persist in populations where malaria is prevalent?

Accepted Answer

Heterozygous individuals have a survival advantage against malaria.

Question 5

Which of the following best describes the quaternary structure of adult hemoglobin (HbA)?

Accepted Answer

A tetramer of two alpha and two beta chains

Question 6

During development, which globin gene is most highly expressed in the embryo, and what is its chain composition?

Accepted Answer

Epsilon globin; two epsilon and two alpha chains

Question 7

A patient receives gene therapy for sickle cell anemia. Which technique is most likely used to modify the stem cells?

Accepted Answer

Sequence-specific nuclease therapy with zinc finger domains

Question 8

Which of the following equations correctly represents the percentage of total globin synthesis for a given globin type over time?

Accepted Answer

$$\frac{	ext{Globin type synthesis}}{	ext{Total globin synthesis}} 	imes 100$$

Question 9

Which of the following is a direct consequence of the aggregation of sickle cell hemoglobin molecules in red blood cells?

Accepted Answer

Formation of rigid fibers that distort red blood cell shape

Question 10

If a population has a sickle cell allele frequency of $$p$$ and a normal allele frequency of $$q$$, which equation represents the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq$$

Question 11

Which of the following best explains the switch from fetal to adult hemoglobin gene expression after birth?

Accepted Answer

A gradual increase in beta globin synthesis and decrease in gamma globin synthesis

Question 12

Which of the following statements about the structure of hemoglobin is correct?

Accepted Answer

Adult hemoglobin (HbA) consists of two alpha and two beta polypeptide chains.

Question 13

A child is born with sickle cell anemia. Which of the following is most likely true about the child’s hemoglobin composition immediately after birth?

Accepted Answer

High levels of fetal hemoglobin (HbF) and low levels of sickle hemoglobin (HbS)

Question 14

Which of the following is a plausible reason for the evolutionary advantage of the sickle cell trait in malaria-endemic regions?

Accepted Answer

Heterozygous individuals are less likely to suffer severe malaria.

Question 15

Which of the following best describes the molecular basis for the sickling of red blood cells in sickle cell anemia?

Accepted Answer

A hydrophobic amino acid replaces a hydrophilic one in the β-globin chain.

Question 16

Which of the following is the correct sequence of globin gene expression from embryo to adult?

Accepted Answer

Epsilon → Gamma → Beta

Question 17

A researcher is studying the effect of gene therapy on sickle cell anemia. Which outcome would indicate successful treatment?

Accepted Answer

Restoration of normal hemoglobin function and red blood cell shape

Question 18

Which of the following is a direct effect of the sickle cell mutation on hemoglobin’s quaternary structure?

Accepted Answer

Formation of abnormal fibers due to hydrophobic interactions

Question 19

Which of the following best explains the clinical symptoms of sickle cell anemia?

Accepted Answer

Reduced oxygen delivery due to rigid, sickle-shaped red blood cells blocking capillaries

Hemoglobin Structure, Gene Expression, and Sickle Cell Anemia

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