Molecular Basis of Inheritance

Amino acid sequence, in protein synthesis is decided by the sequence of -

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

E. coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because -

1. They cannot transport lactose from the medium into the cell
2. They cannot synthesize functional -galactosidase
3. In the presence of glucose, E. coli cells do not utilize lactose
4. The lac operon is constitutively active in these cells

Telomerase is an enzyme which is a -

1. RNA
2. Repetitive DNA
3. Simple protein
4. Ribonucleoprotein

Protein synthesis in an animal cell occurs -

1. On ribosomes present in the nucleolus as well as in cytoplasm
2. On ribosomes present in cytoplasm as well as in mitochondria
3. Only on the ribosomes present in cytosol
4. Only on ribosomes attached to the nuclear envelope and endoplasmic reticulum

Which one of the following makes use of RNA as a template to synthesize DNA -

1. Reverse transcriptase
2. DNA dependent RNA polymerase
3. RNA polymerase
4. DNA polymerase

During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at the point. What is the sequence called?

1. TATA box
2. GGTT box
3. CAAT box
4. AAAT box

Production of a human protein in bacteria by genetic engineering is possible because

1. The human chromosome can replicate in bacterial cell
2. The genetic code is universal
3. Bacterial cell can carry out the RNA splicing reactions
4. The mechanism of gene regulation is identical in humans and bacteria

During replication of a bacterial chromosome DNA synthesis starts from a replication origin site and

1. RNA primers are involved
2. is facilitated by telomerase
3. moves in one direction of the site
4. moves in bi-directional way

Which form of RNA has a structure resembling clover leaf ?

1. r-RNA
2. m-RNA
3. t-RNA
4. hn-RNA

During transcription, if the nucleotide sequence of the DNA strand that is being coded is ATACG, then the nucleotide sequence in the mRNA would be -

1. UAUGC
2. TCTGG
3. UATGC
4. TATGC

The following ratio is generally constant for a given species :-

1. A+CT+G
2. G+CA+T
3. A+GC+T
4. T+CG+A

DNA fingerprinting refers to :-

1. Techniques used for molecular analysis of different specimens of DNA
2. Analysis of DNA samples using imprinting devices
3. Molecular analysis of profiles of DNA samples
4. Techniques used for identification of fingerprints of individuals

The telomeres of eukaryotic chromosomes consist of short sequences of

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

What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?

1. A polypeptide of 49 amino acids will be formed
2. A polypeptide of 25 amino acids will be formed
3. Two polypeptides of 24 and 25 amino acids will be formed
4. A polypeptide of 24 amino acids will be formed

What does "lac" refer to in what we call the lac operon?

1. The number 1,00,000
2. Lac insect
3. Lactase
4. Lactose

During translation initiation in prokaryotes, a GTP molecule is needed in:

1. Association of 30S-mRNA with formyl-met-tRNA
2. Formation of formyl-met-tRNA
3. Association of 50S subunit of ribosome with initiation complex
4. Binding of 30S subunit of ribosome with mRNA

Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as 'start' or 'stop' codon?

1. UUU – Stop
2. UAC – Tyrosine
3. UGU – Leucine
4. UCG – Start

During transcription, the DNA site at which RNA polymerase binds is called:

1. Receptor
2. Regulator
3. Enhancer
4. Promoter

Degeneracy of a genetic code is attributed to the:

1. Second member of a codon
2. Third member of a codon
3. First member of a codon
4. Entire codon

In the genetic code dictionary, how many codons are used to code for all the 20 amino acids:

1. 64
2. 20
3. 60
4. 61

In a DNA percentage of thymine is 20% then what is the percentage of guanine : -

1. 40%
2. 20%
3. 30%
4. 60%

Transformation experiment was first performed on which bacterium : -

1. Diplococcus pneumoniae
2. Pasteurella pestis
3. E. coli
4. Salmonella

Jacob and Monod studied lactose metabolism in E. coli and proposed operon concept. Operon concept is applicable for :

1. All prokaryotes and all eukaryotes
2. All prokaryotes and some protozoans
3. All prokaryotes
4. All prokaryotes and some eukaryotes

In E. coli, during lactose metabolism repressor binds to : -

1. Promoter gene
2. Operator gene
3. Structural gene
4. Regulator gene

Out of 64 codons, 61 codons code for 20 types of amino acids; it is called : -

1. Wobbling of codon
2. Universality of codons
3. Overlapping of gene
4. Degeneracy of genetic code

Which of the following reunites the exon segments after RNA splicing ?

1. RNA polymerase
2. RNA proteases
3. RNA primase
4. RNA ligase

Exon parts of mRNA have code for : -

1. Lipid
2. Protein
3. Phospholipid
4. Carbohydrate

m-RNA is synthesised on DNA template in which direction : -

1. Any
2. Both (3) and (4)
3. 5' → 3'
4. 3' → 5'

In Negative operon : -

1. cAMP has negative effect on lac operon
2. Co-repressor binds with inducer
3. Co-repressor binds with repressor
4. Co-repressor does not bind with repressor

Gene and cistron words are sometimes used synonymously because : -

1. One gene contains one cistron
2. One cistron contains many genes
3. One gene contains no cistron
4. One gene contains many cistrons