3.8.2.2 Regulation of transcription and translation

What is the role of oestrogen in gene transcription in eukaryotes?

• It inhibits transcription by binding to DNA.

• It stimulates transcription by binding to specific transcriptional factors.

• It degrades mRNA to prevent translation.

• It increases methylation of DNA.

Answer explanation

Oestrogen stimulates transcription by binding to specific transcriptional factors, enhancing the expression of target genes. This mechanism is crucial for various biological processes in eukaryotes.

What is epigenetics?

• Changes in the DNA base sequence.

• Heritable changes in gene function without changes to the DNA base sequence.

• The process of DNA replication.

• The synthesis of proteins from mRNA.

Answer explanation

Epigenetics refers to heritable changes in gene function that do not involve alterations to the DNA sequence itself. This distinguishes it from changes in the DNA base sequence, making the second option the correct answer.

Which of the following is a mechanism of epigenetic control?

• Increased methylation of DNA.

• Decreased synthesis of RNA.

• Increased translation of mRNA.

• Decreased degradation of proteins.

Answer explanation

Increased methylation of DNA is a key epigenetic mechanism that can silence gene expression, affecting how genes are turned on or off without altering the DNA sequence itself.

How does decreased acetylation of histones affect gene expression?

• It increases transcription.

• It decreases transcription.

• It increases translation.

• It decreases translation.

Answer explanation

Decreased acetylation of histones leads to a more compact chromatin structure, which restricts access to transcription machinery, thereby decreasing transcription of genes.

What is the relevance of epigenetics in the development of cancer?

• It has no relevance.

• It can lead to changes in gene expression that contribute to cancer.

• It only affects non-cancerous cells.

• It prevents the development of cancer.

Answer explanation

Epigenetics plays a crucial role in cancer development by causing changes in gene expression without altering the DNA sequence. These changes can lead to uncontrolled cell growth and tumor formation, making the correct choice significant.

What is RNA interference (RNAi)?

• A process that increases DNA replication.

• A mechanism that inhibits the translation of mRNA.

• A method to enhance protein synthesis.

• A technique to increase transcription.

Answer explanation

RNA interference (RNAi) is a biological process where small RNA molecules inhibit the translation of specific mRNA, effectively silencing gene expression. Thus, the correct choice is that it inhibits the translation of mRNA.

Which of the following is a potential treatment approach for diseases based on epigenetics?

• Increasing DNA replication.

• Modifying methylation and acetylation patterns.

• Enhancing protein degradation.

• Blocking RNA synthesis.

Answer explanation

Modifying methylation and acetylation patterns is a key epigenetic approach to alter gene expression and potentially treat diseases. The other options do not directly target epigenetic mechanisms.

How can environmental factors influence phenotype?

• By altering the DNA sequence.

• By affecting gene expression through epigenetic changes.

• By changing the number of chromosomes.

• By increasing the rate of cell division.

Answer explanation

Environmental factors can influence phenotype by affecting gene expression through epigenetic changes, which modify how genes are turned on or off without altering the DNA sequence itself.

What is the effect of increased DNA methylation on gene expression?

• It activates gene expression.

• It inhibits gene expression.

• It has no effect on gene expression.

• It enhances protein synthesis.

Answer explanation

Increased DNA methylation typically leads to the repression of gene expression by preventing transcription factors from accessing the DNA, thus inhibiting gene expression.

Which of the following statements is true about transcriptional factors?

• They are only found in prokaryotes.

• They can move from the cytoplasm to the nucleus to regulate transcription.

• They are involved in DNA replication.

• They degrade mRNA.

Answer explanation

Transcription factors are proteins that can move from the cytoplasm to the nucleus, where they bind to DNA and regulate transcription. The other statements are incorrect as they misrepresent the role of transcription factors.