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The question consist of two statements each Assertion (A) and Reason (R) So answer these question choose anyone of the following four respones A:- Mutations effect protein structure and function R :- Only one changed codon may be mis sense when it changes insertion of one aminoacid
What would happen if in a gene encoding polypeptide of 50 aminoacids 25th codon (UAU) is mutated to UAA ? (AIPMT - 2003)
In the given scenario, the original codon (UAU) codes for the amino acid Tyrosine. When it mutates to UAA, it becomes a stop codon. This means that translation will terminate prematurely at this point. Therefore, instead of a polypeptide of 50 amino acids, only the first 24 amino acids will be formed before the translation process stops at the 25th codon. Hence, a polypeptide of 24 amino acids will be formed.
What does “Lac†refer to in what we call the lac operon ? (AIPMT - 2003)
The 'lac' in 'lac operon' stands for 'lactose'. The lac operon is a set of genes with a single promoter that are involved in the metabolism of lactose in Escherichia coli and some other bacteria. When lactose is present, it acts as an inducer by binding to the repressor and allowing transcription of the operon's genes to proceed.
During transcription if the nucleotide sequence of the DNAstrand that is being coded is ATACG then the nucleotide sequence in the m RNA would be (AIPMT - 2004)
During transcription, the DNA sequence is transcribed into mRNA. The base pairing rules are as follows: Adenine (A) pairs with Uracil (U) in RNA, and Cytosine (C) pairs with Guanine (G). Therefore, if the DNA sequence being coded is ATACG, the complementary mRNA sequence would be UAUGC.
Which one of the following makes use of RNA template to synthesize DNA (AIPMT - 2005)
Reverse transcriptase is an enzyme that transcribes RNA into DNA. It is used by retroviruses to integrate their genetic material into the host genome. This process is crucial in molecular biology, especially in the context of retroviruses like HIV.
E coli cells with a mutant z gene of the lac operon cannot grow in mediumcontaining only lactose as the source of energy because (AIPMT - 2005)
The z gene in the lac operon codes for the enzyme beta-galactosidase. This enzyme is responsible for breaking down lactose into glucose and galactose. A mutation in the z gene means that E. coli cannot produce functional beta-galactosidase, thereby making it unable to utilize lactose as an energy source.
Aminoacid Sequence in protein synthesis is decided bythe sequence of (AIPMT - 2006)
The sequence of amino acids in protein synthesis is determined by the sequence of mRNA. During translation, the mRNA sequence is read by the ribosome, and tRNA molecules bring the corresponding amino acids to form a polypeptide chain.
Antiparallel strands of a DNA molecule means that (AIPMT - 2006)
The term 'antiparallel' in the context of DNA refers to the orientation of the two strands of the DNA molecule. In an antiparallel arrangement, the phosphate groups at the start (5' end) of one strand are aligned opposite to the phosphate groups at the start (5' end) of the other strand. This means one strand runs in the 5' to 3' direction, while the complementary strand runs in the 3' to 5' direction.
Polysome is formed by (AIPMT - 2008)
A polysome, or polyribosome, is a complex formed by multiple ribosomes simultaneously translating a single mRNA strand. This arrangement allows for the production of multiple copies of a protein from a single mRNA molecule, thereby increasing the efficiency of protein synthesis.
Semiconservative replication of DNA was first demonstrated in (AIPMT - 2009)
The semiconservative replication of DNA, which means that each of the two new DNA molecules contains one original and one new strand, was first demonstrated in Escherichia coli by Matthew Meselson and Franklin Stahl in 1958. This experiment provided strong evidence for the semiconservative model of DNA replication.
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