Unit 1 Review-Live Session

Which type of point mutation results in a premature stop codon, potentially leading to a non-functional protein?

• Silent Mutation

• Missense Mutation

• Nonsense Mutation

• Frameshift Mutation

Answer explanation

A nonsense mutation introduces a premature stop codon in the mRNA sequence, leading to the production of a truncated protein that is often non-functional. This distinguishes it from silent and missense mutations.

Tags

NGSS.HS-LS3-2

What is the primary effect of a frameshift mutation on a protein?

• It changes one amino acid in the protein.

• It introduces a premature stop codon.

• It shifts the reading frame, altering the entire amino acid sequence downstream.

• It duplicates a portion of the protein.

Answer explanation

A frameshift mutation alters the reading frame of the genetic code, leading to a completely different amino acid sequence downstream. This can significantly impact the protein's function, unlike the other options.

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NGSS.HS-LS3-2

Explain how transcription factors influence gene expression.

• They bind to DNA and change its sequence.

• They bind to RNA and prevent translation.

• They bind to DNA and either enhance or inhibit transcription.

• They modify the amino acid sequence of proteins.

Answer explanation

Transcription factors are proteins that bind to specific DNA sequences. They play a crucial role in regulating gene expression by either enhancing or inhibiting the transcription of genes, thus controlling the production of RNA.

A scientist is using CRISPR-Cas9 to edit a gene. What is the primary purpose of this technology?

• To duplicate genes

• To precisely edit the DNA sequence

• To transcribe RNA into DNA

• To translate proteins into RNA

Answer explanation

The primary purpose of CRISPR-Cas9 is to precisely edit the DNA sequence, allowing scientists to make targeted modifications to genes, which can lead to advancements in genetic research and therapies.

How does epigenetic modification affect gene expression without altering the DNA sequence?

• By changing the sequence of nucleotides

• By adding or removing chemical groups to DNA or histones

• By duplicating the entire chromosome

• By transcribing RNA into DNA

Answer explanation

Epigenetic modification affects gene expression by adding or removing chemical groups to DNA or histones, which alters how genes are accessed and expressed, without changing the underlying DNA sequence.

A student claims that all mutations lead to non-functional proteins. Evaluate this statement.

• True, because all mutations change the protein structure.

• False, because silent mutations do not alter the protein function.

• True, because mutations always introduce stop codons.

• False, because all mutations are corrected by the cell.

Answer explanation

The statement is false because silent mutations do not change the amino acid sequence of a protein, thus they do not affect protein function. Not all mutations lead to non-functional proteins.

Tags

NGSS.HS-LS3-2

Consider a scenario where a gene for insulin production is inserted into bacteria. What is the strategic advantage of this genetic modification?

• It allows bacteria to become resistant to antibiotics.

• It enables bacteria to produce human insulin, aiding diabetes treatment.

• It causes bacteria to grow faster.

• It makes bacteria photosynthetic.

Answer explanation

The strategic advantage of inserting the insulin gene into bacteria is that it enables them to produce human insulin, which is crucial for diabetes treatment, making it a significant biotechnological advancement.

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NGSS.HS-LS1-1

Analyze how gene regulation can lead to different eye colors in humans.

• All humans have the same eye color due to identical genes.

• Different genes are turned on or off, leading to the production of different pigments.

• Eye color is determined by the amount of light exposure.

• Eye color is random and not influenced by genes.

Answer explanation

Different genes regulate the production of pigments in the iris. When certain genes are activated or silenced, they influence the type and amount of pigment produced, resulting in the variety of eye colors seen in humans.

Tags

NGSS.HS-LS3-2

NGSS.HS-LS3-1

A diagram shows a promoter region, transcription factors, and epigenetic modifications. What is the role of the promoter region in gene expression?

• It is where DNA replication begins.

• It is the binding site for RNA polymerase to initiate transcription.

• It is where proteins are synthesized.

• It is the site of DNA repair.

Answer explanation

The promoter region is crucial for gene expression as it serves as the binding site for RNA polymerase, enabling the initiation of transcription, which is the first step in gene expression.

How might CRISPR-Cas9 be used to develop disease-resistant crops?

• By duplicating the entire genome of the crop

• By editing specific genes to enhance resistance to pests and diseases

• By transcribing RNA into DNA

• By inhibiting photosynthesis in the crop

Answer explanation

CRISPR-Cas9 can be used to edit specific genes in crops, enhancing their resistance to pests and diseases. This targeted approach allows for precise modifications, improving crop resilience without altering the entire genome.

Tags

NGSS.HS-LS2-7