Which of the following mechanisms of gene regulation operates after mRNA transcription but before translation of mRNA into protein?
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Solution
RNA processing occurs after transcription and before translation.
In humans, the hormone testosterone enters cells and binds to specific proteins, which in turn bind to specific sites on the cells’ DNA. These proteins probably act to
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Solution
The presence of testosterone enables RNA polymerase to transcribe certain male-specific genes.
During transcription, the DNA site at which RNA polymerase binds is called
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Solution
Regulator is a gene which forms a biochemical for suppressing the activity of operator gene. Promoter is the gene which provides the point of attachment to RNA polymerase required for transcription of structural genes.
During translation initiation in prokaryotes, a GTP molecule is needed in
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Solution
For the formation of initiation complex during translation of mRNA, GTP is also required. The initiator AUG codes for the formylmethionine in prokaryotes.
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 ?
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Solution
AUG is initiating codon. UCG codes for serine, UUU codes for phenylalanine, UGU codes for cysteine.
tRNA takes part in
Lactose operon produces enzymes
What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA?
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Solution
UAA is the stop codon. Therefore at 25th amino acid the synthesis of polypeptide stops. So, a polypeptide of 24 Amino acid is formed.
Protein synthesis occurs
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Solution
Ribosomes are the sites of protein synthesis. Mitochondria being a semi autonomous organelle has its own protein synthesizing machinery.
Which step of translation does not consume a high energy phosphate bond ?
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Solution
During the activation of amino acids, in the presence of Mg2+ and ATP an amino acid gets attached to a specific enzyme aminoacyl t-RNA synthetase. Pyrophosphate is released which breaks up to release energy. During translocation, in the presence of the enzyme translocase and energy from GTP the ribosome moves in such away that the peptidyl bearing t-RNA of A- site comes to lie on the P-site, exposing a new codon at A - site. In the peptidyl transferase reaction energy is provided by GTP.