Q. What is denaturation of proteins?
A.
The process of protein synthesis
B.
The loss of protein function due to structural changes
C.
The formation of peptide bonds
D.
The folding of proteins into their functional shape
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Solution
Denaturation refers to the process where proteins lose their native structure and function due to external factors like heat or pH changes.
Correct Answer: B — The loss of protein function due to structural changes
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Q. What is the function of hemoglobin in the body?
A.
To catalyze reactions
B.
To transport oxygen
C.
To provide structural support
D.
To store energy
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Solution
Hemoglobin is a protein that functions to transport oxygen from the lungs to tissues throughout the body.
Correct Answer: B — To transport oxygen
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Q. What is the isoelectric point (pI) of a protein?
A.
The pH at which the protein is positively charged
B.
The pH at which the protein is negatively charged
C.
The pH at which the protein has no net charge
D.
The pH at which the protein is denatured
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Solution
The isoelectric point (pI) of a protein is the pH at which the protein has no net charge, leading to minimal solubility.
Correct Answer: C — The pH at which the protein has no net charge
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Q. What is the isoelectric point of a protein?
A.
The pH at which the protein is positively charged
B.
The pH at which the protein is negatively charged
C.
The pH at which the protein has no net charge
D.
The pH at which the protein denatures
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Solution
The isoelectric point of a protein is the pH at which the protein has no net charge, leading to minimal solubility.
Correct Answer: C — The pH at which the protein has no net charge
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Q. What is the primary structure of a protein?
A.
The sequence of amino acids
B.
The folding of the polypeptide chain
C.
The arrangement of multiple polypeptide chains
D.
The interaction between side chains
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Solution
The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain.
Correct Answer: A — The sequence of amino acids
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Q. What is the role of enzymes in biological systems?
A.
To provide structural support
B.
To act as catalysts for biochemical reactions
C.
To store genetic information
D.
To transport molecules across membranes
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Solution
Enzymes are proteins that act as catalysts, speeding up biochemical reactions without being consumed in the process.
Correct Answer: B — To act as catalysts for biochemical reactions
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Q. What role do enzymes play in biological systems?
A.
They provide structural support
B.
They act as catalysts for biochemical reactions
C.
They store genetic information
D.
They transport molecules across membranes
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Solution
Enzymes are proteins that act as catalysts, speeding up biochemical reactions without being consumed in the process.
Correct Answer: B — They act as catalysts for biochemical reactions
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Q. What type of bond forms between the carboxyl group of one amino acid and the amino group of another?
A.
Hydrogen bond
B.
Ionic bond
C.
Peptide bond
D.
Disulfide bond
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Solution
A peptide bond forms between the carboxyl group of one amino acid and the amino group of another, linking them together in a protein.
Correct Answer: C — Peptide bond
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Q. What type of interaction is crucial for the tertiary structure of proteins?
A.
Hydrophobic interactions
B.
Covalent bonds
C.
Ionic interactions
D.
All of the above
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Solution
The tertiary structure of proteins is stabilized by a combination of hydrophobic interactions, ionic interactions, hydrogen bonds, and sometimes covalent bonds.
Correct Answer: D — All of the above
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Q. What type of interaction stabilizes the tertiary structure of proteins?
A.
Hydrophobic interactions
B.
Covalent bonds
C.
Ionic interactions
D.
All of the above
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Solution
The tertiary structure of proteins is stabilized by a combination of hydrophobic interactions, ionic interactions, hydrogen bonds, and sometimes covalent bonds.
Correct Answer: D — All of the above
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Q. What type of protein is hemoglobin?
A.
Enzyme
B.
Structural protein
C.
Transport protein
D.
Hormonal protein
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Solution
Hemoglobin is a transport protein that carries oxygen in the blood.
Correct Answer: C — Transport protein
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Q. What type of protein structure involves multiple polypeptide chains?
A.
Primary structure
B.
Secondary structure
C.
Tertiary structure
D.
Quaternary structure
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Solution
The quaternary structure of a protein is formed when two or more polypeptide chains assemble into a functional protein complex.
Correct Answer: D — Quaternary structure
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Q. Which bond is primarily responsible for the secondary structure of proteins?
A.
Ionic bonds
B.
Hydrogen bonds
C.
Disulfide bonds
D.
Peptide bonds
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Solution
The secondary structure of proteins, such as alpha-helices and beta-sheets, is stabilized by hydrogen bonds between the backbone atoms.
Correct Answer: B — Hydrogen bonds
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Q. Which level of protein structure is characterized by the arrangement of multiple polypeptide chains?
A.
Primary structure
B.
Secondary structure
C.
Tertiary structure
D.
Quaternary structure
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Solution
The quaternary structure of a protein refers to the arrangement and interaction of multiple polypeptide chains.
Correct Answer: D — Quaternary structure
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Q. Which level of protein structure is characterized by the overall 3D shape of a single polypeptide chain?
A.
Primary structure
B.
Secondary structure
C.
Tertiary structure
D.
Quaternary structure
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Solution
The tertiary structure of a protein refers to the overall 3D shape of a single polypeptide chain, determined by interactions among side chains.
Correct Answer: C — Tertiary structure
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Q. Which of the following amino acids contains a sulfur atom?
A.
Cysteine
B.
Serine
C.
Glutamine
D.
Alanine
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Solution
Cysteine is the amino acid that contains a sulfur atom in its side chain, which can form disulfide bonds.
Correct Answer: A — Cysteine
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Q. Which of the following is a characteristic of fibrous proteins?
A.
Soluble in water
B.
Structural role
C.
Globular shape
D.
Enzymatic activity
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Solution
Fibrous proteins are typically insoluble in water and serve structural roles in cells and tissues.
Correct Answer: B — Structural role
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Q. Which of the following is a function of proteins in the body?
A.
Energy storage
B.
Hormonal regulation
C.
Transport of molecules
D.
All of the above
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Solution
Proteins serve multiple functions in the body, including energy storage, hormonal regulation, and transport of molecules.
Correct Answer: D — All of the above
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Q. Which of the following is NOT a function of proteins?
A.
Enzymatic activity
B.
Energy storage
C.
Transport of molecules
D.
Cell signaling
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Solution
While proteins can be involved in energy metabolism, they are not primarily used for energy storage; carbohydrates and fats serve that purpose.
Correct Answer: B — Energy storage
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Q. Which of the following techniques is commonly used to determine protein structure?
A.
Mass spectrometry
B.
Nuclear magnetic resonance (NMR)
C.
X-ray crystallography
D.
Both B and C
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Solution
Both nuclear magnetic resonance (NMR) and X-ray crystallography are commonly used techniques to determine the three-dimensional structure of proteins.
Correct Answer: D — Both B and C
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Q. Which of the following techniques is commonly used to separate proteins based on their size?
A.
Chromatography
B.
Electrophoresis
C.
Spectroscopy
D.
Centrifugation
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Solution
Gel electrophoresis is a technique used to separate proteins based on their size and charge.
Correct Answer: B — Electrophoresis
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