This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Chemical Basis of Life – Proteins”.
1. In an amino acid, the carboxyl group and amino group are separated from each other by a single ____________ atom.
Explanation: Proteins are polymers containing amino acids as monomers. There are twenty different types of amino acids, with varying functional groups. Every amino acid has a carboxyl group and an amino group separated by a single carbon atom between them.
2. Amino acids used in the synthesis of proteins on a ribosome are ________________
a) D-amino acids
b) Mutated amino acids
c) L-amino acids
d) Fluorescing amino acids
Explanation: The Cloud User or the cloud consumer or the self-service user decides which computing resources such as CPU, memory, storage etc. to use for their instances.
3. Instances in cloud computing are also known as ___________
c) Virtual Machines
Explanation: D-amino acids have methyl and amide groups located on the right side of the molecule and L-amino acids have methyl and amide groups located on the left side of the molecule. The amino acids used for synthesis of proteins on a ribosome are L-amino acids.
4. Microorganisms use D-amino acids.
Explanation: Unlike animals, microorganism use D-amino acids in the synthesis of certain small peptides, including those present in cell walls and several antibiotics.
5. Which bonds are present in two neighboring amino acids?
a) Glycosidic bonds
b) Polypeptide bonds
c) Amide bonds
d) Hydrogen bonds
Explanation: Peptide bonds are present between two consecutive amino acids. Carboxyl group of one amino acid is bonded to the amino group of neighboring amino acid, by the elimination of water.
6. The longest known polypeptide is of the muscle protein called __________
Explanation: An average polypeptide chain consists of about 450 amino acids. The longest known polypeptide chain is found in the muscle protein called titin, consisting of over 30,000 amino acids.
7. Which of the following amino acids does not belong to polar charged group?
b) Aspartic acid
Explanation: Serine belongs to the category of polar uncharged amino acids whereas aspartic acid, lysine, glutamic acid and arginine belong to polar charged amino acids. These are fully charged at physiological pH and their side chains contain strong organic acids and bases.
8. Histidine is a polar uncharged amino acid.
Explanation: Histidine is considered a polar charged amino acid although it is not fully charged at physiological pH. The ability of Histidine to gain or lose a proton in physiological pH ranges, it is an important residue in active sites of many proteins.
9. Which residues are present in histone proteins?
b) Glutamic acid
Explanation: Histone proteins are highly alkaline proteins around which DNA winds and packaged structures of wound DNA on histones are called nucleosomes. The positively charged arginine residues of histone proteins are linked by ionic bonds to negatively charged phosphate groups of DNA.
10. Which of the following groups of amino acids does not interact with water?
c) Polar charged
d) Polar uncharged
Explanation: The side chains of non-polar amino acids are hydrophobic in nature and therefore do not form electrostatic bonds. The amino acids included in this category are alanine, valine, leucine, isoleucine, tryptophan, phenylalanine and methionine.
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