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 the DNA polymerase delta gene can lead to reduced fidelity of DNA replication. Which of the following would be the MOST LIKELY direct consequence of such a mutation?
Decreased rate of Okazaki fragment synthesis
Inhibition of DNA unwinding by helicase
Increased rate of DNA repair mechanisms
Increased mutation rate in the newly synthesized DNA
Imagine a prokaryotic organism with a mutated DNA polymerase III that lacks 3' to 5' exonuclease activity. What would be the MOST LIKELY consequence of this mutation?
Slower replication fork movement
Inability to initiate DNA replication
A higher rate of mutations in the replicated DNA
Increased formation of Okazaki fragments
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
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 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.
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 mutant strain of E. coli is found where the repressor protein of the lac operon has lost its ability to bind to allolactose. In the presence of lactose, what would be the expected expression level of the lac operon genes in this mutant compared to a wild-type strain?
Higher than wild-type
Lower than wild-type
The same as wild-type
Completely absent
A mutation in the lac operon's promoter region increases its affinity for RNA polymerase. In the presence of both glucose and lactose, how will the expression levels of the lac operon genes be affected compared to a wild-type strain?
No change in expression compared to wild-type.
Increased expression compared to wild-type, but not maximal expression.
Maximal expression of the lac operon genes.
Complete repression of the lac operon genes.
If a mutation occurs in the operator region of the lac operon such that the repressor protein can no longer bind, which of the following scenarios would still result in reduced lac operon expression compared to maximal induction?
Absence of glucose, presence of lactose
High glucose, presence of lactose
Absence of glucose, absence of lactose
High glucose, absence of lactose
