Nucleic acids MCQs

Set of Important MCQs on CHEMISTRY OF NUCLEIC ACIDS for the preparation of tests for chemistry and biology. 

Which one of the following vitamins plays an important role in the biosynthesis of purine nucleotides?

  1. Pyridoxal-amine
  2. Niacin
  3. Cobalamine
  4. Folic Acid

Question Answer: Folic Acid

Which is correct about bacterial chromosome?”

  1. It contains histones
  2. It is evenly distributed throughout the cell
  3. It is locally organized into nucleosome-like structures
  4. It is attached to the inner surface of the plasma membrane

Question Answer: It is attached to the inner surface of the plasma membrane

“PCR” technique is useful for:

  1. Hybridization of DNA
  2. Recombination of DNA
  3. Cloning of DNA
  4. All of these

Question Answer: Cloning of DNA

What is the number of hydrogen bond existing in G-C pair?

  1. 3
  2. 2
  3. 1
  4. 4

Question Answer: 3

Which of the following is the base which is not existing in DNA?

  1. Uracil
  2. Adenine
  3. Guanine
  4. Thymine

Question Answer: Uracil

Which is not a pyrimidine base?

  1. Uracil
  2. Thymine
  3. Guanine
  4. Cytosine

Question Answer: Guanine

The sugar existing in DNA is

  1. D-ribose
  2. D-glucose
  3. 3-Deoxy-D-ribose
  4. 2-Deoxy-D-ribose

Question Answer: 2-Deoxy-D-ribose

Which among the following is the sugar existing in RNA?

  1. D-arabinose
  2. D-ribose
  3. D-glucose
  4. Deoxyribose

Question Answer: D-ribose

Which is the  unit of nucleic acid having base-sugar combination?

  1. Nucleic acid
  2. Nucleotide
  3. Nucleoside
  4. None of these

Question Answer: Nucleoside

Cytosine, a pyrimidine base, pairs with which of the following?

  1. Thymine
  2. Guanine
  3. Adenine
  4. Any of these

Question Answer: Guanine

What is the number of hydrogen bonds holding A-T pair?

  1. 1
  2. 4
  3. 3
  4. 2

Question Answer: 2

Adenosine nucleoside has the base

  1. Guanine
  2. Adenine
  3. Thymine
  4. Cytosine

Question Answer: Adenine

RNA is involved in the synthesis of which of the following?

  1. Nucleic acid
  2. Proteins
  3. Carbohydrates
  4. Fats

Question Answer: Proteins

Which of the following is the formation of daughter DNA’s from parent DNA?

  1. Translation
  2. Replication
  3. Reproduction
  4. Transcription

Question Answer: Replication

Which of the following is the procedure of transfer of genetic message from DNA to m-RNA?

  1. Replication
  2. Translation
  3. Transference
  4. Transcription

Question Answer: Transcription

Hydrogen bonds holding the strands of nucleic acids are formed between ______ and  _____.

  1. Sugar and base units
  2. Base units
  3. Sugar and phosphate units
  4. Sugar units

Question Answer: Base units

Codon for amino acid glycine is not represented by base pair

  1. GGA
  2. GCA
  3. GGC
  4. GGU

Question Answer: GCA

Anticodons in t-RNA’s corresponding to different amino acids ________

  1. Same as in codons
  2. Complimentary to codons
  3. Sometimes as Same as in codons and sometimes as Complimentary to codons
  4. Haphazard in arrangement

Question Answer: Complimentary to codons

One arm of each t-RNA terminates in the base sequence

  1. UGU
  2. GGC
  3. CCA
  4. ACT

Question Answer: CCA

The binding site on ribosome for t-RNA and m-RNA is offered by which of the following?

  1. Ribosomal RNA
  2. Polysome
  3. Codons
  4. DNA

Question Answer: Ribosomal RNA

Biological role of nucleic does not include which of the following?

  1. Genetic continuity
  2. Protein synthesis
  3. Mutation
  4. Hybridization

Question Answer: Hybridization

The steps involved in biosynthesis of protein includes which of the following?

  1. Transcription
  2. Translation
  3. Both of these
  4. None of these

Question Answer: Both of these

How many nucleoprotein subunits does the mammalian ribosome contain?

  1. 6
  2. 1
  3. 2
  4. 5

Question Answer: 2

Which is the most abundant intracellular free nucleotide?

  1. FAD
  2. ATP
  3. NADP
  4. NAD

Question Answer: ATP

Hypoxanthine and ribose are components of _______ molecules.

  1. Adenosine
  2. Guanosine
  3. Inosine
  4. Cytidine

Question’s Answer: Inosine

Which are adapter molecules that translate genetic code into amino acid sequence?

  1. tRNA
  2. mRNA
  3. DNA
  4. rRNA

Question’s Answer: tRNA

All tRNA molecules have a common CCA sequence at the ______ termini.

  1. 4′ termini
  2. 3′ termini
  3. 3, 5′ termini
  4. All of these

Question’s Answer: 3′ termini

A prokaryotic polypeptide of 300 amino acids is encoded by how many base pairs of DNA?

  1. 100 bp
  2. 300 bp
  3. 1800 bp
  4. 900 bp

Question’s Answer: 900 bp

AUG, the only identified codon for methionine, is important as ______ .

  1. A chain initiating codon
  2. A chain terminating codon
  3. A releasing factor for peptide chain
  4. The recognition site on the tRNA

Question’s Answer: A chain initiating codon

The anticodon region is an important part of the structure of which of the following?

  1. rRNA
  2. mRNA
  3. tRNA
  4. hnRNA

Question’s Answer: tRNA

The chief end product of purine catabolism in man is _____.

  1. Urea
  2. Ammonia
  3. Uric acid
  4. Allantoin

Question’s Answer: Uric acid

DNA can be denatured by which of the following?

  1. Alkali
  2. Acid
  3. Heat
  4. All of these

Question’s Answer: All of these

The chemical name 2-amino-6-oxypurine is for ____.

  1. Guanine
  2. Xanthine
  3. Adenine
  4. Hypoxanthine

Question’s Answer: Guanine

The four nitrogen atoms in purine ring are derived from
which of the following?

  1. Aspartate and Glutamine
  2. Aspartate and Glycine
  3. Aspartate, Glycine and Glutamine
  4. Aspartate, Glycine and Ammonia

Question’s Answer: Aspartate, Glycine and Glutamine

Each turn of DNA structure has a pitch in ____nm.

  1. 3.4
  2. 2.4
  3. 2.7
  4. 4.5

Question’s Answer: 3.4

Which statement is correct about histones?

  1. Their amino acid sequences are highly variable among organisms
  2. They are positively charged proteins
  3. They do not undergo any covalent modifications
  4. All of these

Question’s Answer: They are positively charged proteins

The chemical name of thymine would be:

  1. 2, 4-dioxy-5-methylpyrimidine
  2. 2-oxy-4-aminopyri9midine
  3. 2,4-dioxypyrimidine
  4. None of these

Question’s Answer: 2, 4-dioxy-5-methylpyrimidine

The N atoms at position 3 and 9 of purine base are derived from the amide nitrogen____

  1. Glutamate
  2. Glutamine
  3. Asparagine
  4. A

Question’s Answer: Glutamine

Posttranscriptional modification of tRNA involves adding of which of the following?

  1. CCA at 5′ end
  2. Poly A tail at the 3′ end
  3. CCA at 3′ end
  4. 7-methyloguanosine to the 5′ end

Question’s Answer: CCA at 3′ end

The end product of purine catabolism is ________  in other mammals, excluding man.

  1. Uric acid
  2. Ammonia
  3. Allantoin
  4. Creatinine

Question’s Answer: Allantoin

The transfer-RNA approximately molecule comprises how many nucleotides?

  1. 74-95
  2. 70-84
  3. 93-105
  4. >110

Question’s Answer: 74-95

Histones are:

  1. Acidic chromosomal proteins
  2. Basic proteins associated with
  3. Acidic polysomal proteins RNA
  4. Basic proteins associated with DNA

Question’s Answer: Basic proteins associated with DNA

The structural stability of the double helix of DNA is largely the result of which of the following?

  1. Hydrogen bonding between adjacent purine bases
  2. Hydrogen bonding between stacked purine and pyrimidine bases
  3. The energy released due to the turning of the nucleic acid molecule
  4. Hydrogen bonding between purine and pyrimidine bases of the two chains

Question’s Answer: Hydrogen bonding between stacked purine and pyrimidine bases

A mature mRNA could be lengthier than its precursor pre-mRNA due to which of the following?

  1. Polyadenylation
  2. Splicing
  3. 5′-end capping
  4. None of these

Question’s Answer: Polyadenylation

Which processes does not happen in the nucleus of eukaryotes?

  1. Polyadenylation
  2. Translation
  3. Pre-mRNA splicing
  4. 5′-end capping of mRNAs

Question’s Answer: Translation

How many energy bonds are helpful and used up during the elongation step in protein synthesis?

  1. One
  2. Four
  3. Three
  4. Two

Question’s Answer: Two

mRNA is a complimentary copy of which?

  1. 5′-3′ strand of DNA
  2. Antisense strand of DNA
  3. Coding strand of DNA
  4. tRNA

Question’s Answer: Coding strand of DNA

For DNA-dependent RNA synthesis

  1. A RNA template and DNA primer are required
  2. A DNA template and RNA primer are required
  3. A DNA template and DNA primer are required
  4. Only the DNA template is required

Question’s Answer: Only the DNA template is required

Which statements regarding a double-helical of DNA is correct?

  1. All hydroxyl groups of pentoses are involved in linkages
  2. Bases are parallel to the long axis
  3. both the strands are identical
  4. Both the strands are parallel

Question’s Answer: All hydroxyl groups of pentoses are involved in linkages

Which is NOT correct regarding eukaryotic mRNA?

  1. They are translated sequentially over their length
  2. They are derived from precursor RNAS
  3. They have poly A. tails at their 3 ends
  4. They have 7-methyl GTP caps at their 5′ ends

Question’s Answer: They are translated sequentially over their length

Translocate is an enzyme required in the process of:

  1. DNA replication
  2. RNA synthesis
  3. Initiation of protein synthesis
  4. Elongation of peptides

Question’s Answer: Elongation of peptides

Nonsense codons bring about ________.

  1. Amino acid activation
  2. Initiation of protein synthesis
  3. Termination of protein synthesis
  4. Elongation of polypeptide chains

Question’s Answer: Termination of protein synthesis

Which is not a component of polysomes?

  1. Proteins
  2. tRNA
  3. mRNA
  4. DNA

Question’s Answer: DNA

In which way are the genomes of prokaryotes and eukaryotes similar?

  1. Both have genes that are precisely collinear with the amino acid sequences
  2. Both have chromosome (s) that are longer than the cell.
  3. BOTH have satellite DNA
  4. Both have multiple chromosomes

Question’s Answer: Both have chromosome (s) that are longer than the cell.

Which is NOT CORRECT about genetic code

  1. There may be as many as six codons for a single amino acid
  2. There are different codons for initiating methionine and internal methionine
  3. All the 64 possible codon are helpful and used during translation
  4. The arrangement of the genetic code table is Non-Random

Question’s Answer: There are different codons for initiating methionine and internal methionine

Reverse transcriptase enzyme catalyzes

  1. Formation of RNA using DNA template
  2. Peptidyl transformation
  3. DNA hybridization
  4. RNA directed DNA polymerization

Question’s Answer: RNA directed DNA polymerization

Where protein synthesis takes place predominantly in the mammalian secretory cells?

  1. Endoplasmic reticulum
  2. Nucleolus
  3. Nucleus
  4. Lysosomes

Question’s Answer: Endoplasmic reticulum

DNA ligase:

  1. Transfers AMP to the 5′ phosphate
  2. Catalyzes the formation of a phosphodiester bond between 3’and 5′ ends
  3. group at a nick Fills in gaps
  4. Provides the phosphate group needed to form a phosphodiester bond

Question’s Answer: Catalyzes the formation of a phosphodiester bond between 3’and 5′ ends

When double-stranded DNA is slowly warmed at 85°C?

  1. The hydrogen bonding between G-C pairs breaks before that between A-T
  2. The absorbance at 260 nm increases
  3. Purine bases are cleaved from deoxyribose
  4. The viscosity of DNA increases

Question’s Answer: The absorbance at 260 nm increases

The term “Transforming factors” has been helpful and used for _______ ?

  1. DNA
  2. RNA
  3. tRNA
  4. None of these

Question’s Answer: DNA

An accurate DNA replication needed all of the following, EXCLUDING

  1. A RNA primer
  2. DNA ligase
  3. 5′-3′ exonuclease activity
  4. A free 5′-OH

Question’s Answer: A free 5′-OH

The purine nucleotides act as the components of: factor

  1. Coenzyme A
  2. Fibrin stabilizing
  3. CTP
  4. All of these

Question’s Answer: Coenzyme A

Approximately……….mg of uric acid is synthesized in a normal man in 24 hours

  1. 200-300
  2. 500-600
  3. 400-500
  4. 300-400

Question’s Answer: 500-600

Which is correct about DNA gyrase?

  1. It underwinds DNA supercoils decreasing linking number
  2. It introduces positive supercoiling of DNA upstream of the fork
  3. It is a tapir’s topoisomerase
  4. All of these

Question’s Answer: It introduces positive supercoiling of DNA upstream of the fork

Promoters:

  1. Are required for elongation of transcription
  2. Are recognized by RNA polymerases in a sequence-dependent manner
  3. Are encoded by the DNA template strand
  4. Tend to be G-C rich

Question’s Answer: Are recognized by RNA polymerases in a sequence-dependent manner

Which is correct about reverse transcriptase?

  1. Its activity can be detected only in cells infected with retroviruses
  2. It has a low error rate
  3. It does not require a primer to initial synthesis
  4. None of these

Question’s Answer: Its activity can be detected only in cells infected with retroviruses

The normal function of restriction endonucleases is to:

  1. Excise introns from hnRNA
  2. Polymerize núcleotides to from RNA
  3. Remove proteins from Okazaki fragments
  4. Protect bacteria rom foreign DNA

Question’s Answer: Protect bacteria rom foreign DNA

The E.coli RNA polymerases binding to the promoter site is inhibited by:

  1. Rifampicin
  2. Streptomycin
  3. Aureomycin
  4. Terramycin

Question’s Answer: Rifampicin

Which is not a purine base?

  1. Guanine
  2. Adenine
  3. Cytosine
  4. None of these

Question’s Answer: Cytosine

Hydrolysis of nucleoprotein results in the formation of which of the following?

  1. Proteins
  2. Nucleic acids
  3. Both A. and B.
  4. They do not hydrolyze

Question’s Answer: Both A. and B

Complete hydrolysis of nucleotides results in the formation of which of the following?

  1. Heterocyclic bases
  2. A phosphate ion
  3. A pentose
  4. All of these

Question’s Answer: All of these

Which proteins unwinds the two parental DNA strands in E.coli?

  1. DNA gyrase
  2. Primase
  3. SSB protein
  4. Helicase

Question’s Answer: Helicase

PCR can be helpful and used for:

  1. Cloning DNA fragments from mummies
  2. As a forensic tool
  3. Detection of viral infection BC
  4. All of these.

Question’s Answer: All of these

Foot-printing technique is helpful and used to:

  1. Detect the single base pair defect
  2. Detect the protein binding site
  3. Identify the TATA and Pribnow boxes
  4. Detect the restriction endonuclease sites

Question’s Answer: Detect the protein binding site

Which nucleotides is helpful and used for epimerization of galactose to glucose?

  2. CTP
  3. GTP
  4. UTP

Question’s Answer: UTP

Which compounds is structural analogue of hypoxanthine and competitively inhibits xanthine oxidase?

  1. Ara C
  2. 5-Fluorouracil
  3. 5-phosphoribosylpyrophosphate (PRPP)
  4. Allopurinol

Question’s Answer: Allopurinol

Which is correct for ‘Alternative splicing:

  1. Gives rise to different arrangements of genomic DNA
  2. Results in distinct proteins with a number of common domains
  3. Needed different U1 suRNAS
  4. Results from different proteolytic processing events

Question’s Answer: Results in distinct proteins with a number of common domains

Which is not existing in both E.coli and human mRNA?

  1. Polyadenylation signals
  2. Shine-Dalgarno sequence
  3. Initiation codons
  4. None of these

Question’s Answer: Shine-Dalgarno sequence

Which is a best example of homologous genetic recombination?

  1. Transposition
  2. Crossing over during meiosis
  3. Immunoglobulin gene recombination
  4. Integration of bacteriophage DNA

Question’s Answer: Crossing over during meiosis

More Biochemistry MCQs

  1. Acid and Base MCQs
  2. Carbohydrate MCQs
  3. Proteins MCQs
  4. Lipids and Biomembranes MCQs
  5. Nucleic acids MCQs
  6. Metabolism of Carbohydrates MCQs
  7. Enzymes MCQs
  8. Vitamins and Hormones MCQs
  9. Bioenergetic MCQs
  10. Biotechnology MCQs
  11. Biotechnology MCQs 2
  12. Basic Biochemistry MCQs (important)
  13. CHEMISTRY MCQs From all subjects of  Chemistry

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