A very low level of expression of the lac operon has to be present in the cell:
(1) When lactose is present
(2) When lactose is absent
(3) When glucose is absent
(4) All the time
(1) When lactose is present
(2) When lactose is absent
(3) When glucose is absent
(4) All the time
The lac operon is regarded as:
(1) Negative, Inducible
(2) Negative, Repressible
(3) Positive, Inducible
(4) Positive, Repressible
A piece of nucleic acid used to find a gene, by forming a hybrid with it, is called a
1. Probe
2. Vector
3. Restriction sequence
4. Retrovirus
Hybridization of mRNA with DNA can reveal which segment of the DNA are introns and which segment are exons. When the magnification is high enough to see the molecule, the introns appear as
1. Single stranded loops in a double stranded molecule
2. Separate fragments
3. Triple stranded nucleic acid molecules
4. Barr bodies
The repressor of lac operon is:
(1) Lactose itself
(2) A steroid
(3) Synthesized constitutively
(4) A product of structural gene
Gene regulation in prokaryotes is carried out exclusively at the level of:
(1) Initiation of transcription
(2) Post transcriptional modifications
(3) Translation
(4) Post translational modifications
The UTR [untranslated regions] in an mRNA:
(1) Are present only at 5’ end and are not required for efficient translation
(2) Are present only at 3’ end and are not required for efficient translation
(3) Are present at both 5’ and 3’ ends and are not required for efficient translation
(4) Are present at both 5’ and 3’ ends and are required for efficient translation process
Which of the following acts as a ribozyme for peptide bond formation in bacteria?
(1) 5s rRNA
(2) 23s rRNA
(3) 16s rRNA
(4) 5.1s rRNA
Which of the following anticodons will hybridize with the mRNA codon 5’ – AUG – 3’?
1. 5’ – UAC – 3’
2. 5’ – TAC – 3’
3. 3’ – UAC – 5’
4. 3’ – TAC – 5’
In actual structure, tRNA is a compact molecule which looks like a/an:
(1) Clover leaf
(2) Rail road
(3) Inverted L
(4) Alpha helix
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