Amino Acids and Proteins - Practice Questions

Aspartame, an artificial dipeptide sweetener containing phenylalanine, carries a warning for phenylketonurics. Which characteristic BEST describes phenylalanine?

GABA, a neurotransmitter, is formed by decarboxylation of an amino acid's alpha-carboxyl group. Which amino acid is MOST likely the precursor to GABA?

An enzyme involved in intermediary metabolism contains alpha-helices. Which statement BEST describes the alpha-helical secondary structure?

A research group studies covalent bonds in the tertiary structure of proteins. Which bond are they MOST likely studying?

In E. coli, glucose is converted to chorismate, an intermediate in the synthesis of histidine, phenylalanine, tyrosine, and tryptophan. Which of the following statements BEST describes gene expression for tryptophan synthesis in these bacteria?

During translation, a tRNA molecule interacts with mRNA. If the positions of nucleotides in the tRNA and mRNA are numbered sequentially, which position on the tRNA best indicates the location of the first nucleotide of the anticodon?

A research laboratory studies a disease-causing gene leading to loss of enzyme function. Karyotyping and DNA microarray show no chromosomal changes. Northern blot analysis shows normal mRNA transcript levels. Western blot shows a smaller protein. Which mutation is most consistent with these findings?

Insulin undergoes modification after synthesis. The primary insulin translation product is modified to produce the mature hormone. Which modification is most likely observed during this process?

A bacterial strain has reduced translation rates due to decreased activity in peptide bond formation; this inhibits ribosomal protein synthesis. A mutation in which of the following is most consistent with these findings?

A mutation in the gene encoding aminoacyl-tRNA synthetase would directly affect which of the following processes?

A researcher introduces a mutation into the gene for a prokaryotic ribosomal protein. This mutation specifically impairs the ability of the ribosome to bind mRNA. Where is the most likely location of this mutation?

Which of the following is NOT a typical modification that occurs to eukaryotic proteins after translation?

When the anticodon of a tRNA base pairs with the codon of an mRNA, what is the orientation of their directionality?

A lab observes a disease-causing gene exhibiting a loss of enzyme function. Karyotyping and DNA microarray reveal an unchanged chromosome structure. Northern blot analysis shows no change in mRNA transcript levels, but Western blot analysis indicates a smaller than normal protein. Which mutation is most likely responsible?

An insertion of 'GCG' into an exon of a gene will most likely result in which outcome?

If the codon 'CCC' is mutated to 'CCG', what is the most likely consequence?

What is the most likely outcome of a splice site mutation?

A 99% reduction in promoter function will most likely lead to which of the following?

If a western blot shows a smaller than normal protein, and a northern blot shows no change in mRNA transcript of the gene, what can you conclude?

In a scenario where a disease-causing gene shows no change in chromosome structure or mRNA transcript but produces a smaller protein, which mutation is least likely?

What event is crucial for ribosome function on a polycistronic mRNA during bacterial translation?

In the context of bacterial translation involving polycistronic mRNA, which statement accurately characterises the initiation process at AUG codons?

What type of post-translational modification is most likely observed during the maturation of insulin from its primary translation product?

During translation, a researcher observes that multiple proteins are being produced from a single mRNA molecule in a bacterial cell. Which of the statements below is the likeliest explanation?

A bacterial strain exhibits reduced rates of translation due to decreased activity in peptide bond formation. A mutation in which component is most consistent with these findings?

Which modification does NOT occur post-translationally in eukaryotes?

Considering the structure and function of tRNA in translation, which position corresponds to the first nucleotide of the anticodon that interacts with the mRNA codon?

A researcher observes that a newly synthesized pre-proinsulin molecule is not being correctly processed into mature insulin. Which of the following is LEAST likely to be the cause?

A scientist mutates a bacterial gene, resulting in the production of a non-functional enzyme. Further analysis reveals that the mRNA transcribed from the mutated gene is polycistronic, but only the first protein in the cistron is produced. What is the most likely cause of this?

Which of the given options, is a direct participant in the recognition and alignment of mRNA on the ribosome during translation in prokaryotes?

A researcher discovers a new bacterial species with a unique translation mechanism. The mRNA produced is polycistronic, but unlike other bacteria, each protein in the cistron is produced in equal amounts, regardless of its position in the mRNA. Which of the following would best explain this observation?

A researcher is studying a protein that requires glycosylation to be fully functional. Where would this process occur?

What is the function of the start codon AUG in eukaryotic protein synthesis?

During translation, where does the amino acid bind to the tRNA?

Which of the following antibiotics primarily inhibits the translocation step of translation in bacteria?

During the nomenclature of a nucleic acid, how is the order in which it's named described?

Which of the given options is NOT required to achieve the elongation step in prokaryotic translation?

Which of the following mutations is MOST likely to result in a protein that is produced in normal amounts but fails to be secreted from the cell?

Which of the following drugs inhibits bacterial DNA replication?

What is the target of rifamycin?

Which eukaryotic translation inhibitor targets peptidyl transferase activity?

Which of the following drugs is classified as a nucleoside analog and inhibits DNA replication?

Which of the following drugs inhibits eukaryotic RNA polymerase II?

Which of the following antibiotics inhibits the aminoacyl tRNA entry into the A site of the ribosome?