52 Questions
Which of the following is true about the HBB gene mutation?
It can cause aberrant splicing of pre-mRNA, leading to reduced levels of functional beta-globin protein and anemia.
What is the function of telomeres?
They are specialized structures at chromosome ends, maintained by telomerase to protect DNA from degradation during replication.
What is the primary composition of collagen chains?
Proline and glycine, contributing to the stability of the triple helix structure.
What is the role of aspirin and ibuprofen?
They are inhibitors of the enzyme cyclooxygenase (COX), involved in the production of prostaglandins.
What is the role of the anomeric carbon in carbohydrates?
It undergoes rotation during the ring-opening and closing process in carbohydrates.
What is the common theme in DNA binding proteins' structure?
The presence of a specific helix lying across the major groove of DNA.
Which amino acid side chains can be phosphorylated by protein kinases?
Serine, threonine, tyrosine
What is the likely cause of elevated serum amylase and lipase levels in a 48-year-old man with acute abdominal pain?
Acute pancreatitis
What type of enzyme kinetics are common for multimeric enzymes, showing cooperative binding of substrates and allosteric modulation?
Sigmoidal kinetics
Which method cannot detect fructose as a reducing sugar?
Clinitest
Which type of amino acids are more likely to be exposed to water in a folded protein structure?
Polar amino acids
What is the likely cause of fetal warfarin syndrome in children of mothers taking warfarin during pregnancy?
Inhibition of vitamin K-dependent gamma-carboxylation of glutamate
What is the primary role of retinal, a form of vitamin A?
Vision
Which group is involved in the conversion of B-carotene to retinal in the intestinal mucosa?
Carotene dioxygenase
Which type of protein modification is phosphorylation?
Reversible post-translational modification
Where do non-polar amino acids usually form a cluster in a helical protein?
In the middle
What type of amino acids are more likely to be found in the interior of a folded protein?
Non-polar amino acids
What is the prosthetic group of rhodopsin?
Retinal
What type of bond is formed between two sugar molecules through the reaction between the anomeric carbon of one sugar and the hydroxyl group of another sugar?
Glycosidic bond
What is the common structural motif found in many DNA binding proteins, involved in the recognition and binding of specific DNA sequences?
Helix-turn-helix (HTH)
What type of bonds do DNA binding proteins form with DNA?
Hydrogen bonds with the nitrogenous bases
What enzyme is responsible for removing the phosphate group from phosphorylated amino acid residues, thus reversing the effects of kinases?
Phosphatase
What process do synthetases catalyze by joining two substrates using ATP?
Ligation
What is the major attractive force between DNA and proteins, allowing the formation of specific types of DNA-protein complexes during the cell cycle?
Electrostatic interactions
What transports retinol to the liver after processing by the intestinal mucosa?
Plasma retinol-binding protein (RBP)
What enzyme hydrolyzes glycosidic bonds, which are covalent bonds that link a sugar molecule to another molecule?
a-glycosidase
What is responsible for cleaving B-carotene in the intestinal mucosa, yielding retinal?
Beta-carotene dioxygenase
What can phosphorylation of specific amino acid residues in proteins do to the function of enzymes, membrane transporters, and other proteins?
Activate or deactivate
How many possible configurations (R and S) do chiral carbon atoms in sugars have?
Two
What is a common mechanism for regulating cellular signaling pathways and controlling various cellular processes such as metabolism, growth, and differentiation?
Phosphorylation
Which amino acids can be ionizable in water due to certain side chains or carboxyl groups?
Polar amino acids
What is the primary protein structure of hemoglobin and myoglobin?
Alpha helices
Which coenzyme is required for the action of pyruvate carboxylase?
Biotin
What gene mutations lead to Wilson's disease?
ATP7B
Which of the following is a characteristic of the genetic code?
Universal
Why are enzymes effective catalysts?
They decrease the free energy of activation
What is the primary function of alpha-1-antitrypsin?
Inhibiting neutrophil elastase
Do enzymes catalyze reactions that would not occur at all?
No
How do enzymes affect the equilibrium point of reactions?
Do not affect it
What change do enzymes bring to the rate of both forward and reverse reactions?
Increase the rate of both equally
What does alpha-1-antitrypsin compromise in the alpha1-globulin fraction of normal serum?
More than 90%
Is alpha-1-antitrypsin involved in the formation of elastin cross-links?
No
Which of the following amino acids is considered hydrophobic at physiological pH of 7.4?
Isoleucine
In B-thalassemia, patients with significantly reduced levels of B-globin transcripts and elevated levels of HbF exhibit no detectable HbA1 due to:
Splicing alteration of the B-globin mRNA
Which of the following amino acid side chains may be considered as hydrophobic at physiological pH of 7.4?
Isoleucine
In B-thalassemia, patients with significantly reduced levels of B-globin transcripts and elevated levels of HbF exhibit no detectable HbA1 due to:
Splicing alteration of the B-globin mRNA
What is a common mechanism for regulating cellular signaling pathways and controlling various cellular processes such as metabolism, growth, and differentiation?
Covalent modification of proteins
What is the major attractive force between DNA and proteins, allowing the formation of specific types of DNA-protein complexes during the cell cycle?
Ionic bonding
Which of the following amino acid side chains may be considered as hydrophobic at physiological pH of 7.4?
Isoleucine
In B-thalassemia, patients with significantly reduced levels of B-globin transcripts and elevated levels of HbF and no detectable HbA1 exhibit these observations due to:
Splicing alteration of the B-globin mRNA
Which of the following forms of amino acid side chains can form hydrogen bonds with water molecules?
Serine
In hemoglobin, which amino acid is responsible for the nonpolar side chain that is hydrophobic?
Leucine
Study Notes
Biochemistry and Genetics Summary
- Polar amino acids with certain side chains or carboxyl groups can be ionizable in water.
- Hemoglobin and myoglobin primarily consist of alpha helices, a common secondary protein structure.
- Pyruvate carboxylase deficiency requires biotin as a coenzyme for its action.
- Wilson's disease is caused by mutations in the ATP7B gene and leads to copper accumulation in the body.
- The genetic code is degenerate, unambiguous, nonoverlapping, without punctuation, and universal.
- Enzymes are effective catalysts because they decrease the free energy of activation of reactants.
- Alpha-1-antitrypsin inhibits neutrophil elastase and is involved in elastin biosynthesis.
- Enzymes do not catalyze reactions that would not occur at all or shift the equilibrium of reactions toward more complete conversion to product.
- Enzymes increase the rate of both the forward and reverse reactions equally, without affecting the equilibrium point of the reaction.
- Enzymes do not affect the standard free energy change (∆G 0) of reactions, only reducing the activation energy of the reaction.
- Alpha-1-antitrypsin compromises more than 90% of the alpha1-globulin fraction of normal serum and is mainly produced in the liver.
- Alpha-1-antitrypsin inhibits N- or C-terminal procollagen peptidases and is not involved in the formation of elastin cross-links.
Test your knowledge of biochemistry and genetics with this quiz. From amino acid properties to genetic disorders and enzyme functions, this quiz covers essential concepts in biochemistry and genetics.
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