Prepare for NEET Biology Molecular Basis of Inheritance with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert explanations of DNA replication and genetics.
A mutation changes a codon from UCG to UAG. This mutation is a:
Missense mutation
Silent mutation
Frameshift mutation
Nonsense mutation
Certain mutations in tRNA can suppress nonsense mutations in mRNA. This phenomenon is MOST directly related to alterations in which part of the tRNA?
Acceptor stem
D-loop
T\u03a8C loop
Anticodon loop
Imagine a scenario where a novel amino acid is discovered. If the existing genetic code must accommodate this new amino acid without altering the existing amino acid assignments, what is the MOST likely mechanism for achieving this?
Expansion of the codon length from three to four bases
Overlapping reading frames
Reassignment of a rarely used codon
Modification of the ribosome structure
Which of these scenarios would MOST likely lead to a frameshift mutation that affects the downstream amino acid sequence?
Substitution of one nucleotide for another
Deletion of three nucleotides in the coding sequence
Insertion of two nucleotides in the coding sequence
Inversion of a segment of DNA containing a multiple of three nucleotides
A researcher discovers a bacterial strain with an unusual genetic code. In this strain, the codon UAG, typically a stop codon, codes for tryptophan. Which of the following would be the MOST direct consequence of this altered genetic code?
Premature termination of protein synthesis
No effect on protein synthesis
Substitution of tryptophan with another amino acid
Elongation of proteins past the normal termination point
Wobble base pairing allows a single tRNA to recognize multiple codons. Which position of the codon exhibits the MOST flexibility in wobble pairing?
First base
Second base
Third base
All bases exhibit equal flexibility
During translation, a tRNA molecule carrying a specific amino acid recognizes the corresponding codon on the mRNA through its anticodon. A mutation occurs in the anticodon loop of a tRNA specific for alanine, changing it from 3'-CGI-5' to 3'-CCI-5'. Assuming the wobble hypothesis applies, what is the MOST LIKELY consequence of this mutation?
The tRNA will no longer recognize any codons.
The tRNA will insert glycine into the polypeptide chain instead of alanine.
The tRNA will still carry alanine but will recognize different alanine codons.
The mutation will have no effect on protein synthesis.
A researcher is studying translation in a prokaryotic cell. They introduce a modified mRNA where all the guanine nucleotides in the coding sequence are replaced with inosine. Which of the following is the MOST LIKELY effect on translation?
Translation will terminate prematurely due to the presence of inosine.
The ribosome will be unable to bind to the modified mRNA.
The protein synthesized will be identical to the one produced from the unmodified mRNA.
The protein synthesized will have altered amino acid sequence due to changes in codon recognition.
A mutation changes a codon from UAU (Tyrosine) to UAC (Tyrosine). This is an example of which type of mutation?
Missense mutation
Nonsense mutation
Frameshift mutation
Silent mutation
