Question 1

In sickle cell hemoglobin, a Glu is mutated to a _______. This causes the formation of _______ between hemoglobin molecules, ultimately forming large aggregates.

Accepted Answer

A) Arg; salt bridges 
B) Cys; disulfide bonds 
C) Val; hydrophobic interactions 
D) Pro; disrupted $\alpha$-helix, resulting in several H-bonds and salt bridges 
E) none of the above 
A) Arg; salt bridges 
B) Cys; disulfide bonds 
C) Val; hydrophobic interactions 
D) Pro; disrupted $\alpha$-helix, resulting in several H-bonds and salt bridges 
E) none of the above

Question 2

Which of the following is the first step in the clonal selection theory for antibody production?

Accepted Answer

A) binding of an antigen to an antibody on a B lymphocyte stimulates the cell to replicate 
B) B stem cells in the bone marrow differentiate to become B lymphocytes 
C) immunoglobulins are exposed on the outer surfaces of the B lymphocytes 
D) effector B cells and memory cells are produced 
E) helper T cells recognize a bound antigen, bind to B lymphocytes and stimulate B cell reproduction 
A) binding of an antigen to an antibody on a B lymphocyte stimulates the cell to replicate 
B) B stem cells in the bone marrow differentiate to become B lymphocytes 
C) immunoglobulins are exposed on the outer surfaces of the B lymphocytes 
D) effector B cells and memory cells are produced 
E) helper T cells recognize a bound antigen, bind to B lymphocytes and stimulate B cell reproduction

Question 3

When oxygen is bound to myoglobin, the amino acid _____ is complexed to the iron ion of the heme group while _______ forms a hydrogen bound to the oxygen.

Accepted Answer

A) cysteine; serine 
B) cysteine; histidine 
C) serine; cysteine 
D) histidine; histidine 
E) histidine; cysteine 
A) cysteine; serine 
B) cysteine; histidine 
C) serine; cysteine 
D) histidine; histidine 
E) histidine; cysteine

Question 4

A typical Hill plot (log [YO2/(1- YO2)] vs log PO2)for hemoglobin-oxygen binding does not yield a straight line as it does for myoglobin. Which of the following is the best explanation for this?

Accepted Answer

A) at high oxygen pressures, hemoglobin is in a low oxygen affinity state 
B) at low oxygen pressures, hemoglobin is in a high oxygen affinity state 
C) hemoglobin undergoes a transition from low affinity state under low oxygen pressure to a high affinity state under high oxygen pressure 
D) hemoglobin undergoes a transition from high affinity state under low oxygen pressure to a low affinity state under high oxygen pressure 
E) none of the above 
A) at high oxygen pressures, hemoglobin is in a low oxygen affinity state 
B) at low oxygen pressures, hemoglobin is in a high oxygen affinity state 
C) hemoglobin undergoes a transition from low affinity state under low oxygen pressure to a high affinity state under high oxygen pressure 
D) hemoglobin undergoes a transition from high affinity state under low oxygen pressure to a low affinity state under high oxygen pressure 
E) none of the above

Question 5

Why do individuals who are heterozygous for sickle cell anemia have a resistance to malaria?

Accepted Answer

A) formation of hemoglobin aggregates makes red blood cells impervious to parasitic infection 
B) shortened life span of red blood cells does not allow sufficient time for the parasite to mature in the red blood cell 
C) diminished blood flow to the skin as a result of sickled red blood cells blocking capillaries prevents mosquitoes from actually transferring the malaria parasite to individuals 
D) sickle cell hemoglobin fibers have both decreased O2 and CO2 carrying capacity; since CO2 is a mosquito attractant, diminished CO2 exhalation does not attract mosquitoes 
E) none of the above 
A) formation of hemoglobin aggregates makes red blood cells impervious to parasitic infection 
B) shortened life span of red blood cells does not allow sufficient time for the parasite to mature in the red blood cell 
C) diminished blood flow to the skin as a result of sickled red blood cells blocking capillaries prevents mosquitoes from actually transferring the malaria parasite to individuals 
D) sickle cell hemoglobin fibers have both decreased O2 and CO2 carrying capacity; since CO2 is a mosquito attractant, diminished CO2 exhalation does not attract mosquitoes 
E) none of the above

Question 6

Which of the following mutations is correctly defined?

Accepted Answer

A) silent: change of a single base in the non-coding intron region of a gene 
B) missense: substitution of a single base results in a premature stop codon 
C) nonsense: substitution of a single base results in a complete change of amino acid sequence 
D) frameshift: deletion of a single base results in a single amino acid change 
E) permissive: results in a protein that has greater thermodynamic stability 
A) silent: change of a single base in the non-coding intron region of a gene 
B) missense: substitution of a single base results in a premature stop codon 
C) nonsense: substitution of a single base results in a complete change of amino acid sequence 
D) frameshift: deletion of a single base results in a single amino acid change 
E) permissive: results in a protein that has greater thermodynamic stability

Question 7

One would expect that defects in the globin genes would be so serious as to cause death in utero. Which of the following explains how some thalassemias are found in living people?

Accepted Answer

A) in $\beta$-thalassemia, the use of the $\gamma$ subunit allows individuals to live a normal lifespan 
B) individuals who completely lack functional $\alpha$ subunits can live if placed in a hypobaric chamber to induce hypoxia 
C) since humans have 4 copies of the $\alpha$ chain gene, effects are only seen when at least 3 of the genes are nonfunctional 
D) individuals with nonfunctional $\alpha$ chain genes can make $\beta$2$\gamma$2 tetramers that function normally 
E) none of the above 
A) in $\beta$-thalassemia, the use of the $\gamma$ subunit allows individuals to live a normal lifespan 
B) individuals who completely lack functional $\alpha$ subunits can live if placed in a hypobaric chamber to induce hypoxia 
C) since humans have 4 copies of the $\alpha$ chain gene, effects are only seen when at least 3 of the genes are nonfunctional 
D) individuals with nonfunctional $\alpha$ chain genes can make $\beta$2$\gamma$2 tetramers that function normally 
E) none of the above

In sickle cell hemoglobin, a Glu is mutated to a _. This causes the formation of _ between hemoglobin molecules, ultimately forming large aggregates.

Which of the following is the first step in the clonal selection theory for antibody production?

When oxygen is bound to myoglobin, the amino acid _ is complexed to the iron ion of the heme group while ___ forms a hydrogen bound to the oxygen.

A typical Hill plot (log [Y_O₂/(1- Y_O₂)] vs log P_O₂)for hemoglobin-oxygen binding does not yield a straight line as it does for myoglobin. Which of the following is the best explanation for this?

Why do individuals who are heterozygous for sickle cell anemia have a resistance to malaria?

Which of the following mutations is correctly defined?

One would expect that defects in the globin genes would be so serious as to cause death in utero. Which of the following explains how some thalassemias are found in living people?

The Scope of Biochemistry

The Matrix of Life: Weak Interactions in an Aqueous Environment

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Contractile Proteins and Molecular Motors

Carbohydrates: Sugars, Saccharides, Glycans

Lipids, Membranes and Cellular Transport

Enzymes: Biological Catalysts

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Citric Acid Cycle and Glyoxylate Cycle

Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism I: Fatty Acids, Triacylglycerols, and Lipoproteins

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Lipid Metabolism Ii: Membrane Lipids, Steroids, Isoprenoids, and Eicosanoids

Metabolism of Nitrogenous Compounds I: Principles of Biosynthesis, Utilization, and Turnover

Metabolism of Nitogenous Compounds II: Amino Acids, Porphyrins, and Neurotransmitters

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes, Genomes and Chromosomes

DNA Replication

DNA Restructuring: Repair, Recombination, Rearrangement, Amplification

Information Readout: Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

Filters

Exam 7: Protein Function and Evolution

In sickle cell hemoglobin, a Glu is mutated to a _______. This causes the formation of _______ between hemoglobin molecules, ultimately forming large aggregates.

Which of the following is the first step in the clonal selection theory for antibody production?

When oxygen is bound to myoglobin, the amino acid _____ is complexed to the iron ion of the heme group while _______ forms a hydrogen bound to the oxygen.

A typical Hill plot (log [YO2/(1- YO2)] vs log PO2)for hemoglobin-oxygen binding does not yield a straight line as it does for myoglobin. Which of the following is the best explanation for this?

Why do individuals who are heterozygous for sickle cell anemia have a resistance to malaria?

Which of the following mutations is correctly defined?

One would expect that defects in the globin genes would be so serious as to cause death in utero. Which of the following explains how some thalassemias are found in living people?

The Scope of Biochemistry

The Matrix of Life: Weak Interactions in an Aqueous Environment

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Contractile Proteins and Molecular Motors

Carbohydrates: Sugars, Saccharides, Glycans

Lipids, Membranes and Cellular Transport

Enzymes: Biological Catalysts

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Citric Acid Cycle and Glyoxylate Cycle

Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism I: Fatty Acids, Triacylglycerols, and Lipoproteins

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Lipid Metabolism Ii: Membrane Lipids, Steroids, Isoprenoids, and Eicosanoids

Metabolism of Nitrogenous Compounds I: Principles of Biosynthesis, Utilization, and Turnover

Metabolism of Nitogenous Compounds II: Amino Acids, Porphyrins, and Neurotransmitters

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes, Genomes and Chromosomes

DNA Replication

DNA Restructuring: Repair, Recombination, Rearrangement, Amplification

Information Readout: Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

Filters

In sickle cell hemoglobin, a Glu is mutated to a _. This causes the formation of _ between hemoglobin molecules, ultimately forming large aggregates.

When oxygen is bound to myoglobin, the amino acid _ is complexed to the iron ion of the heme group while ___ forms a hydrogen bound to the oxygen.

A typical Hill plot (log [Y_O₂/(1- Y_O₂)] vs log P_O₂)for hemoglobin-oxygen binding does not yield a straight line as it does for myoglobin. Which of the following is the best explanation for this?