UIL Biology Topic 4: Gene Expression Questions

What is the primary function of mRNA in protein synthesis?

• To carry amino acids

• To transport DNA

• To serve as a template for protein synthesis

• To form ribosomes

• To regulate gene expression

Answer explanation

The primary function of mRNA is to serve as a template for protein synthesis. It carries the genetic information from DNA to the ribosomes, where proteins are assembled based on the sequence of nucleotides in the mRNA.

Which enzyme is responsible for transcribing DNA into RNA?

• DNA polymerase

• RNA polymerase

• Ligase

• Helicase

• Topoisomerase

Answer explanation

RNA polymerase is the enzyme that synthesizes RNA from a DNA template during transcription, making it the correct answer. Other enzymes listed have different roles in DNA replication and repair.

What is the role of tRNA in protein synthesis?

• To carry genetic information

• To form ribosomes

• To transport amino acids to the ribosome

• To splice exons

• To catalyze peptide bond formation

Answer explanation

tRNA's primary role in protein synthesis is to transport amino acids to the ribosome, where they are assembled into proteins. This is crucial for translating the genetic code into functional proteins.

Which of the following is a start codon in mRNA?

• UGA

• UAA

• AUG

• UAG

• CUA

Answer explanation

AUG is the start codon in mRNA, signaling the beginning of protein synthesis. The other options (UGA, UAA, UAG) are stop codons, which terminate translation.

What is a point mutation?

• A change in the number of chromosomes

• A change in a single nucleotide base pair

• A duplication of a gene segment

• A deletion of a large DNA segment

• An inversion of a chromosome segment

Answer explanation

A point mutation specifically refers to a change in a single nucleotide base pair in the DNA sequence. This distinguishes it from other types of mutations, such as chromosomal changes or larger segment alterations.

Tags

NGSS.HS-LS3-2

Which process involves the removal of introns from pre-mRNA?

• Translation

• Replication

• Splicing

• Transcription

• Mutation

Answer explanation

Splicing is the process that removes introns from pre-mRNA, allowing the remaining exons to be joined together. This is essential for producing a mature mRNA molecule that can be translated into a protein.

What is the function of a ribosome in protein synthesis?

• To replicate DNA

• To transcribe RNA

• To synthesize proteins by linking amino acids

• To degrade mRNA

• To transport tRNA

Answer explanation

The correct choice is 'To synthesize proteins by linking amino acids' because ribosomes are the cellular machinery that assembles proteins by connecting amino acids in the order specified by mRNA during translation.

Which type of mutation results in a premature stop codon?

• Missense mutation

• Nonsense mutation

• Silent mutation

• Frameshift mutation

• Duplication mutation

Answer explanation

A nonsense mutation introduces a premature stop codon in the mRNA sequence, leading to truncated proteins. In contrast, missense mutations change one amino acid, silent mutations do not affect the protein, and frameshift mutations alter the reading frame.

Tags

NGSS.HS-LS3-2

What is the lac operon an example of?

• Eukaryotic gene regulation

• Prokaryotic gene regulation

• Viral replication

• DNA replication

• RNA splicing

Answer explanation

The lac operon is a classic example of prokaryotic gene regulation, specifically in bacteria like E. coli. It controls the metabolism of lactose and demonstrates how genes can be turned on or off in response to environmental changes.

Which molecule is directly involved in the regulation of gene expression by binding to DNA?

• Ribosomal RNA

• Transfer RNA

• Transcription factors

• Messenger RNA

• DNA polymerase

Answer explanation

Transcription factors are proteins that bind to specific DNA sequences, regulating gene expression by promoting or inhibiting the transcription of genes. Other options do not directly bind to DNA.