Molecular Basis of Inheritance

Which of the following is NOT a stop codon in the genetic code?

1. UAA
2. UAG
3. UGA
4. AUG

Which scientist proposed the "Central Dogma of Molecular Biology"?

1. James Watson
2. Francis Crick
3. Erwin Chargaff
4. Frederick Griffith

Which one of the following statements correctly describes the lac operon?

1. It is an example of positive regulation only.
2. It remains active even in the absence of lactose.
3. It is an inducible operon involved in lactose metabolism.
4. It functions only in eukaryotic cells.

The enzyme responsible for synthesizing messenger RNA during transcription in eukaryotes is:

1. DNA Polymerase
2. RNA Polymerase II
3. DNA Ligase
4. Reverse Transcriptase

Which of the following enzymes is responsible for joining Okazaki fragments during DNA replication?

1. DNA Helicase
2. DNA Polymerase
3. DNA Ligase
4. RNA Polymerase

The codon AUG serves as:

1. A stop codon only
2. The initiation codon and codes for methionine
3. A termination codon
4. The codon for glycine

The genetic code is described as "degenerate" because:

1. One codon codes for more than one amino acid.
2. Multiple codons can specify the same amino acid.
3. Codons overlap during translation.
4. Every amino acid is coded by only one codon.

Which RNA molecule carries amino acids to the ribosome during protein synthesis?

1. Messenger RNA (mRNA)
2. Ribosomal RNA (rRNA)
3. Transfer RNA (tRNA)
4. Small nuclear RNA (snRNA)

The process by which genetic information stored in DNA is copied into messenger RNA (mRNA) is called:

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

Meselson and Stahl demonstrated that DNA replication is:

1. Conservative
2. Dispersive
3. Semi-conservative
4. Non-conservative

The enzyme DNA polymerase synthesizes a new DNA strand only in the:

1. 3' to 5' direction
2. 5' to 3' direction
3. Both directions simultaneously
4. Random direction

Which enzyme is primarily responsible for unwinding the DNA double helix during replication?

1. DNA polymerase
2. DNA ligase
3. Helicase
4. Primase

Who proposed the double-helical model of DNA in 1953?

1. Watson and Crick
2. Meselson and Stahl
3. Griffith and Avery
4. Hershey and Chase

According to Chargaff's rule, which of the following relationships is correct in double-stranded DNA?

1. Adenine equals Cytosine
2. Guanine equals Thymine
3. Adenine equals Thymine and Guanine equals Cytosine
4. Adenine plus Guanine equals Cytosine plus Uracil

Which experiment conclusively proved that DNA is the genetic material in most organisms?

1. Griffith's transformation experiment
2. Hershey and Chase experiment
3. Meselson and Stahl experiment
4. Beadle and Tatum experiment

________ is given the credit for developing DNA fingerprinting.

1. Ian Wilmut
2. Har Gobind Khurana
3. Jacob Monod
4. Alex Jeffreys

Satellite DNA is classified into many categories such as micro-satellites, mini-satellites on the basis of

1. Base composition (A:T rich or G:C rich)
2. Length of segment
3. Number of repetitive units
4. All of these

DNA fingerprinting involves identifying the differences in some specific regions in DNA sequence called

1. Non-repetitive DNA
2. Coding DNA
3. Non-coding DNA
4. Repetitive DNA

Which is present at 5' end of eukaryotic mRNA?

1. Poly-A tail
2. Modified C at 5'
3. 7-methylguanosine cap (7mG)
4. Poly-C

DNA-dependent DNA polymerases catalyzes polymerization in which direction?

1. 3' → 5'
2. 5' → 2'
3. 5' → 3'
4. 2' → 5'

Central dogma in molecular biology states that genetic information flows from

1. DNA to mRNA and then to Protein
2. RNA to DNA and then to Protein
3. RNA to RNA and then to Protein
4. DNA to RNA and then to Protein

Smooth strain of Streptococcus S-strain is due to

1. Protein
2. Mucopolysaccharide
3. Lipid
4. Nucleic acid

Correct sequence in Blending experiment of Hershey and Chase

1. Centrifugation, blending, infection
2. Infection, blending, centrifugation
3. Blending, infection, centrifugation
4. Infection, centrifugation and blending

Part of chromatin which is densely packed, stains darkly and is transcriptionally inactive is called

1. Euchromatin
2. Chromatosome
3. Heterochromatin
4. Chromosome

Which of the following is present in DNA

1. Ribose
2. Uracil
3. Purine
4. All

Commonly used vectors for human genome sequencing are

1. T-DNA
2. BAC and YAC
3. Expression vectors
4. T/A cloning vectors

Father of DNA fingerprinting is?

1. Alec Jeffreys
2. Lalji Singh
3. V.K. Kashyap
4. E.M. Southern

Transfer of DNA from an agarose gel to a nitrocellulose or nylon membrane is referred to

1. Western transfer
2. Northern transfer
3. Eastern transfer
4. Southern transfer

In lac operon, the structural genes are switched off when

1. Repressor binds to operator
2. Repressor binds to promoter
3. Repressor binds to regulator
4. Repressor binds to inducer

In lac operon, the genes a, i, y and z code respectively for?

1. Repressor protein, permease, β-galactosidase, transacetylase
2. Transacetylase, permease, β-galactosidase, repressor protein
3. β-galactosidase, transacetylase, repressor protein, permease
4. Transacetylase, repressor protein, permease, β-galactosidase

Lactose operon is considered to be glucose sensitive due to

1. Catabolic induction
2. Allosteric inhibition
3. Anabolic inhibition
4. None of the above

Which of the following set of options is used in translation?

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

During translation, the P-site on the ribosome receives directly

1. Amino acid
2. AA1 - tRNA
3. mRNA with codon
4. mRNA with anticodon

The first amino acid in any polypeptide chain of prokaryotes is always?

1. Formylated methionine
2. Formylated arginine
3. Lysine
4. Methionine

Dr. Har Gobind Khorana was instrumental in synthesizing RNA molecules with defined combinations of

1. Homopolymers
2. Heteropolymers
3. Homo-Oligomers
4. Hetero-Oligomers

Three dimensional shape of tRNA is

1. Inverted L-shaped
2. Clover leaf-like
3. X-shaped
4. Y-shaped

Which out of the following statements is incorrect about genetic code?

1. Genetic code is ambiguous
2. Genetic code is degenerate
3. Genetic code is universal
4. Genetic code is non-overlapping

How many adenylate residues are added at 3' end of hn RNA?

1. 300-400
2. 200-300
3. 400-500
4. 100-200

RNA polymerase III transcribes

1. tRNA
2. ssDNA
3. mRNA
4. Reverse transcriptase

mRNA, rRNA and tRNA are

1. Genetic RNA
2. Non genetic RNA
3. Both (1) and (2)
4. Present in all viruses

The strand of DNA which synthesises mRNA is

1. Sense strand
2. Antisense strand
3. Non-sense strand
4. Half sense and half non-sense strand

Ultimate biological unit which controls heredity is called

1. Genome
2. Genotype
3. Chromosome
4. Gene

Which one of the following is not applicable to RNA?

1. Chargaff's rule
2. Complementary base pairing
3. 5' phosphoryl and 3' hydroxyl ends
4. Heterocyclic nitrogenous bases

During DNA replication, synthesis of leading and lagging strand require?

1. Single primer
2. Single and many primers respectively
3. Many and single primers respectively
4. Many primers

E.coli with completely radioactive DNA, allowed to replicate in non-radioactive medium for two generations. Percentage of bacteria with radioactive DNA is

1. 50%
2. 12.5%
3. 100%
4. 25%

DNA replication in the lagging strand of most eukaryotic organisms is

1. Conservative and Continuous
2. Semi-conservative but discontinuous
3. Conservative and semi-discontinuous
4. Semi-conservative and continuous

Experiment of Avery et al. proved DNA is the genetic material. Which showed positive result?

1. Live R-strain + DNA from S-strain + RNAse
2. Live R-strain + DNA from S-strain + DNAse
3. Live R-strain + Denatured DNA of S-strain + Protease
4. Heat Killed R-strain + DNA from S-strain + DNAse

In some viruses, RNA is present instead of DNA indicating that

1. Their nucleic acid must combine with host DNA before replication
2. They cannot replicate
3. There is no hereditary information
4. RNA can act to transfer heredity

Stability as one of the properties of genetic material was very evident in

1. Griffith's transforming principle
2. Hershey and Chase experiment
3. Meselson & Stahl's centrifugation technique
4. Taylor's experiment

Which is the transcriptionally active chromatin?

1. Euchromatin
2. Heterochromatin
3. Tightly packed chromatin
4. Both (2) and (3)

Nucleosome is

1. Intron interrupted DNA
2. Double helix DNA
3. Negatively charged DNA wrapped around positively charged histone octamer
4. Satellite DNAs

How many nucleosomes are present in human cell

1. 3.3×10⁷ nucleosome
2. 1.1×10⁷ nucleosome
3. 6.6×10⁷ nucleosome
4. Indefinite

The haploid content of human DNA is

1. 3.3×10⁹ bp
2. 3.3×10⁹ kbp
3. 4.6×10⁶ bp
4. 48502 bp

Genetic information in a DNA molecule are coded in the

1. Number of bases
2. Sequence of nucleotides
3. Length of DNA
4. Number of nucleosides

5-methyl uracil is

1. Another name of thymine
2. A purine base
3. A double ring structure
4. Both (1) and (3)