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.
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 transcription elongation in eukaryotes, which of the following is NOT a function of the C-terminal domain (CTD) of RNA polymerase II?
Recruiting DNA polymerase for DNA repair during transcription
Coordinating capping of the 5' end of the pre-mRNA
Facilitating splicing of the pre-mRNA
Recruiting factors for polyadenylation of the 3' end of the pre-mRNA
A mutation in a eukaryotic gene results in the production of a truncated protein lacking its C-terminal region. Analysis reveals a mutation within an intron of the gene. Which of the following is the MOST likely explanation?
The mutation disrupted a splicing enhancer sequence, leading to exon skipping.
The mutation created a new promoter within the intron.
The mutation disrupted the polyadenylation signal, preventing proper termination.
The mutation created a premature stop codon within the intron.
Which statement BEST describes the difference between rho-dependent and rho-independent transcription termination in prokaryotes?
Rho-dependent termination requires a helicase activity, while rho-independent termination relies on a hairpin structure and a poly-U sequence.
Rho-dependent termination occurs only in the presence of specific antibiotics, while rho-independent termination is the normal mechanism.
Rho-dependent termination utilizes sigma factor, while rho-independent termination utilizes rho factor.
Rho-dependent termination involves the formation of a G-quadruplex structure, while rho-independent termination involves a stem-loop structure.
In eukaryotes, the TATA box is a crucial promoter element. Which of the following statements about its function is INCORRECT?
It directly recruits RNA polymerase II to the promoter.
It is recognized by TATA-binding protein (TBP).
It helps determine the transcription start site.
It is typically located approximately 25-30 base pairs upstream of the transcription start site.
A researcher identifies a novel eukaryotic transcription factor. Experiments reveal that this factor binds to a DNA sequence downstream of the transcription start site. Which of the following is the MOST likely role of this factor?
Initiating transcription by recruiting RNA polymerase
Repressing transcription by blocking RNA polymerase binding
Enhancing transcription elongation or termination
Modifying the chromatin structure around the promoter
Which of the following is NOT a direct product of transcription?
A polypeptide chain
rRNA
tRNA
mRNA
