Gene Expression and Regulation
Which of the following scenarios would most likely result in a functional protein despite the presence of a nonsense mutation early in the mRNA sequence?
A ribosome reads through the stop codon due to a tRNA with an altered anticodon that pairs with the stop codon.
An RNA polymerase attaches an incorrect nucleotide opposite the mutated base during transcription.
A chaperone protein assists in proper folding of the polypeptide chain past the point of mutation.
A spliceosome removes the exon containing the nonsense mutation during pre-mRNA processing.
What is termination in the process of translation?
The tRNA is ejected and the ribosome disassemble.
The mRNA is broken down
The ribosome is discarded and degraded
The polypeptide is freed from the ribosome
During elongation in eukaryotic translation, what would be affected if eEF2 were inhibited?
The translocation of tRNA from A-site to P-site on ribosome would be prevented.
Peptidyl transferase activity catalyzing peptide bond formation would diminish.
The binding affinity between mRNA and small ribosomal subunit would decrease.
The initiation complex formation at met-tRNA would be impaired.
Given cells expressing mutant eukaryotic release factors incapable of recognizing standard stop codons accurately during termination phase of translation, which cellular adaptation could potentially compensate for this deficiency?
Nonsense-mediated decay mechanisms become upregulated as a quality control response eliminating aberrant mRNAs before they accumulate toxic proteins
Enhanced activity peptidyl transferase enzyme promoting hydrolysis bond between final tRNA nascent peptide even absence conventional cues
Increased recruitment non-canonical release factors hat recognize these novel signals ensuring proper termination session cases where typical factors fail
Reduced efficiency RNA polymerase II transcription thereby decreasing production defective messenger RNAs carrying erroneous signal sequences
What molecule does a tRNA carry and add to the growing polypeptide chain during translation?
A sugar molecule.
A fatty acid.
A nucleotide.
An amino acid.
Which aspect of the elongation phase would be directly affected by a chemical that inhibits peptidyl transferase activity inside ribosomes?
Preventing recognition of correct anti-codons
Initiation complex including both small and large subunits
Breaking apart disassembly post-termination
Formation of peptide bonds between incoming adjacent molecules
How does a codon relate to an anticodon during translation?
It codes directly for a protein.
It pairs with its complementary anticodon on tRNA.
It transfers peptides.
It binds directly with an amino acid.

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In what way can a single nucleotide polymorphism (SNP) located within an exon that leads to a missense mutation predominantly influence cellular functions during translation?
Due primarily to more frequent occurrences of frame-shifts caused by SNPs altering reading frames in exons.
An SNP-induced missense mutation would mostly cause widespread nonspecific immune responses against altered peptide sequences presented by MHC I molecules.
This type of SNP would typically lead to complete absence of functional proteins due to targeted degradation via proteasomes, due to nonsense-mediated decay pathways being triggered during or after translation completion.
It may result in an altered protein functionality if it affects critical regions such as catalytic sites or interaction domains.
Where does translation occur in eukaryotic cells?
Golgi apparatus
Nucleus
Cytoplasm
Mitochondria
When analyzing two separate populations subject to different selective pressures how might synonymous substitutions observed at higher rates than nonsynonymous substitutions affect long-term evolutionary trajectories?
Higher rates synonymous substitution imply negative selection against any change including advantageous ones thereby directly hindering adaptive potential
Synonymous substitutions always reflect neutral drift unrelated selective forces therefore they do not provide information regarding adaptive significance
Nonsynonymous substitutions always indicate stronger natural selection driving faster adaptation thus higher synonymous substitution rates signal slower evolution
Synonymous substitutions suggest purifying selection maintaining stability while allowing hidden variation that may later contribute adaptive changes under new conditions