Epigenetics and Ageing Quiz

What is DNA methylation?

• The addition of a methyl group to DNA, often affecting gene expression

• The removal of a methyl group from DNA, increasing gene expression

• The addition of a phosphate group to DNA, altering its structure

• The removal of a phosphate group from DNA, decreasing gene expression

Answer explanation

DNA methylation refers to the addition of a methyl group to DNA, which can influence gene expression by silencing genes or altering their activity. This process is crucial for regulating various biological functions.

Which of the following is a common effect of epigenetic changes in ageing cells?

• Increased cell division

• Decreased cellular senescence

• Altered gene expression patterns

• Enhanced DNA repair mechanisms

Answer explanation

Epigenetic changes in ageing cells commonly lead to altered gene expression patterns, affecting how genes are turned on or off, which can impact cellular function and contribute to the ageing process.

How does DNA methylation typically change with age?

• It decreases uniformly across the genome

• It increases uniformly across the genome

• It becomes more variable, with some regions gaining and others losing methylation

• It remains constant throughout life

Answer explanation

With age, DNA methylation becomes more variable, as some regions gain methylation while others lose it. This reflects the complex changes in gene regulation and cellular function that occur over time.

What role do non-coding RNAs play in epigenetics?

• They code for proteins that directly modify DNA

• They are involved in the regulation of gene expression without coding for proteins

• They are responsible for DNA replication

• They are involved in the synthesis of ribosomal RNA

Answer explanation

Non-coding RNAs regulate gene expression by interacting with DNA, RNA, or proteins, influencing processes like transcription and translation without coding for proteins, making them crucial in epigenetics.

Which of the following is NOT a type of epigenetic modification?

• DNA methylation

• Histone acetylation

• RNA splicing

• Histone methylation

Answer explanation

RNA splicing is a process that modifies RNA after transcription, not an epigenetic modification. In contrast, DNA methylation, histone acetylation, and histone methylation are all types of epigenetic modifications that affect gene expression.

Which type of non-coding RNA is known to be involved in gene silencing?

• Messenger RNA (mRNA)

• Transfer RNA (tRNA)

• MicroRNA (miRNA)

• Ribosomal RNA (rRNA)

Answer explanation

MicroRNA (miRNA) is a type of non-coding RNA that plays a crucial role in gene silencing by binding to target mRNA, leading to its degradation or inhibition of translation, thus regulating gene expression.

What is the effect of histone acetylation on gene expression?

• It silences gene expression

• It activates gene expression

• It has no effect on gene expression

• It deletes the gene

Answer explanation

Histone acetylation adds acetyl groups to histones, reducing their positive charge and loosening DNA binding. This promotes a more open chromatin structure, facilitating transcription and thereby activating gene expression.

What is the role of long non-coding RNAs (lncRNAs) in ageing?

• They code for proteins that repair DNA

• They are involved in the regulation of gene expression related to ageing

• They increase the rate of cell division

• They decrease the rate of protein synthesis

Answer explanation

Long non-coding RNAs (lncRNAs) play a crucial role in regulating gene expression, which is essential for understanding the mechanisms of ageing. They do not code for proteins but influence various biological processes related to ageing.

How do microRNAs (miRNAs) influence gene expression?

• They bind to DNA and alter its sequence

• They degrade mRNA or inhibit its translation

• They enhance the transcription of genes

• They are involved in protein folding

Answer explanation

MicroRNAs (miRNAs) primarily influence gene expression by binding to mRNA molecules, leading to their degradation or inhibiting their translation into proteins. This regulatory mechanism is crucial for controlling gene activity.

What is the impact of DNA methylation on gene expression?

• It always increases gene expression

• It can either increase or decrease gene expression depending on the context

• It has no impact on gene expression

• It only affects non-coding regions of the genome

Answer explanation

DNA methylation can regulate gene expression by either silencing genes or enhancing their activity, depending on factors like the gene's context and the specific methylation patterns involved.