Exams Prep Master
Proteins are organic compounds found in all living organisms. They are one of three macromolecule classes, the other two being carbohydrates and lipids. Proteins play numerous roles in living organisms, including metabolic, structural, and signaling functions. Eggs, pulses, milk, and other milk products are examples of high-protein foods for the body. Proteins are long-chain molecules composed of amino acid strings that have been linked together.
All amino acids have the same basic structure: an amino group, a carboxyl group, and a side chain. There are 20 different types of amino acids, which are the building blocks for all proteins. The digestive system breaks down proteins into amino acids, which are small enough to pass from our digestive system into our blood. They are then reconstructed as proteins and used in a variety of ways. To test food for protein, a copper sulfate solution and a sodium hydroxide solution are required. In this article, based on the complexity, importance, and weightage of the respective chapters MCQs are carefully selected. Students can secure more marks in their exams if they practice these MCQs.
Ques: What is the name of an amino acid bond?
(a) The ionic bond
(b) The acidic bond
(c) Peptide bond
(d) The hydrogen bond
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Ans: c
Explanation: A peptide bond is a chemical bond formed between two molecules when one's carboxyl group reacts with the amino group of the other, releasing a molecule of water (H2O). The resulting CO-NH bond is known as a peptide bond, and the molecule is known as an amide.
Ques: A peptide bond is a -
a) covalent bond
b) ionic bond
c) metallic bond
d) hydrogen bond.
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Ans: a
Explanation: A peptide bond is created by covalently joining two amino acids together via a substituted amide linkage.
Ques: A tripeptide contains-
- 3 amino acids and 1 peptide bond
- 3 amino acids and 2 peptide bonds
- Three amino acids and three peptide bonds
- Three amino acids and four peptide bonds
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Ans: b
Explanation: A monopeptide is a peptide composed of a single amino acid, a dipeptide of two amino acids joined by one peptide bond, and a tripeptide of three amino acids joined by two peptide bonds.
Ques: The factor which does not affect pKa value of an amino acid is _________
a) The loss of charge in the α-carboxyl and α-amino groups
b) The interactions with other peptide R groups
c) Other environmental factors
d) Molecular weight
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Ans: d
Explanation: The loss of charge in the α-carboxyl and α-amino groups, the interactions with other peptide R groups and other environmental factors can affect the pKa.
Ques: Which of the following is a 39-residue hormone of the anterior pituitary gland?
a) Corticotropin
b) Glucagon
c) Insulin
d) Bradykinin
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Ans: a
Explanation: Corticotropin is a 39-residue anterior pituitary gland hormone that stimulates the adrenal cortex.
Ques: Which of the following methods is used to determine the structure of proteins?
- X-ray crystallography
- Kryptonics x-ray vision
- Magnetic resonance imaging
- None of the preceding
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Ans: a
Explanation: Protein X-ray crystallography is a technique that uses x-ray diffraction of a crystallised form of a protein to determine its three-dimensional structure. Making crystals creates a lattice in which this technique aligns millions of protein molecules together to increase the sensitivity of data collection.
Ques: Which of the following is not a conjugated protein's classified form?
- Lipoproteins
- Glycoproteins
- Metalloproteins
- Lipoproteins
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Ans: d
Explanation: Conjugated proteins are classified into lipoproteins, glycoproteins, and metalloproteins based on the chemical nature of their prosthetic groups.
Ques: What makes amino acids unique?
- Amino group
- Carboxyl group
- Side chain
- None of the above
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Ans: c
Explanation: At this position, each amino acid is bound to a distinct chemical group known as its side chain. This side chain is what distinguishes each amino acid, giving each amino acid a distinct set of chemical properties.
Ques: Which of the following information is responsible for determining a protein's three-dimensional shape?
a) The peptide bond of the protein
b) The amino acid sequence of the protein
c) The protein's interaction with other polypeptides
d) The protein's interaction with molecular chaperones
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Ans: b
Explanation: A protein's three-dimensional shape is determined by its amino acid sequence.
Ques: The process of a protein unfolding is known as.
- Renaturation
- Denaturation
- Oxidation
- Reduction
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Ans: b
Explanation: The denaturation process causes proteins to lose their quaternary, tertiary, and secondary structures and return to their native state.
Ques: Which of the following is not a factor that causes protein denaturation?
a) Changes in pH
b) Organic solvents
c) Warm-up
d) Charge
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Ans: d
Explanation: Protein denaturation is caused by changes in pH, organic solvents, and heat.
Ques: What are the molecules that hydrolyze to produce amino acids?
- Proteins
- DNA
- RNA
- Ribosomes
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Ans: a
Explanation: A substance is hydrolyzed when water is added to it. Amino acids are the building blocks of proteins and cannot be further broken down.
Ques: A protein is made up of how many amino acids?
- 10
- 20
- 30
- 50
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Ans: b
Explanation: Although there are approximately 500 amino acids identified in nature, only 20 amino acids are found in human body proteins.
Ques: What is in a protein molecule?
- Oxygen
- Carbon dioxide
- Nitrogen
- Both a and c
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Ans. Proteins are made up of carbon, hydrogen, oxygen, nitrogen, and sulphur.
Ques: The proteins serve as the foundation for the major structural components of __
- permanent tissue
- plant tissue
- animal tissue
- meristem stem.
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Ans: c.
Explanation: Proteins are necessary for life and are the primary structural components of animal tissues (e.g., skin, muscles, wool, feather, tendons, eggs).
Ques: What are the proteins that only give a single amino acid when hydrolyzed?
- Simple proteins
- Conjugated proteins
- Derived proteins.
- All of the preceding
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Ans: a
Explanation: Simple proteins are hydrolyzed to produce only amino acids and a few small carbohydrate compounds. Some examples include albumins, globulins, glutelins, albuminoids, histones, and protamines.
Ques: What is the name of the simple protein found in blood?
- Ovolbumin
- Lactalbumin
- Serum albumin
- Legumelin
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Ans: c.
Explanation: The most abundant blood protein in mammals is serum albumin, which is produced by the liver and found dissolved in blood plasma.
Ques: In the protein classification, the globular proteins are __ in nature.
- Supersaturated
- Saturated
- Unsaturated
- water-soluble
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Ans: d
Explanation: Because of the structural arrangement of amino acids, globular proteins are highly soluble in water. As previously stated, hydrophilic amino acids are found on the surface of globular proteins, whereas hydrophobic amino acids are found within.
Ques: The resulting nucleoproteins combined with DNA are found in
- Chromosomes
- DNA
- RNA
- All of the above
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Ans: a
Explanation: The protein that is commonly combined with DNA is histone or protamine; the resulting nucleoproteins are found in chromosomes.
Ques: The __ of milk is a phosphoprotein.
- Casein
- Ovovittelin
- Tendomucoid
- Mucin
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Ans: a
Explanation: Casein proteins are phosphoproteins that account for roughly 80% of the total protein in bovine milk.
Ques: Which of the following cell organelles is involved in the protein synthesis process?
- Vesicles
- Ribosomes
- Synchrotrons
- Mitochondria
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Ans: b
Explanation: The ribosome is responsible for protein synthesis throughout the body by translating the genetic code transcribed in mRNA into an amino acid sequence. Ribosomes initiate, elongate, and terminate peptide synthesis using cellular accessory proteins, soluble transfer RNAs, and metabolic energy.
Ques: What is the average molecular weight of an amino acid residue in a protein?
(a) 120
(b) 110
(c) 130
(d) 140
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Ans: (b) 110
Explanation: An amino acid's average molecular weight is 110 Da. The atomic mass unit is known as the dalton (Da), and a kilodalton (kDa) is 1,000 daltons. Thus, a protein with a molecular weight of 64,000 grammes per mole has a mass of 64kDa.
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