GC content

Question 1

What does high GC content refer to?

Answer 1

Regions of DNA with a higher proportion of guanine (G) and cytosine (C) bases compared to adenine (A) and thymine (T).

Question 2

Why is high GC content significant for thermal stability?

Answer 2

GC pairs form three hydrogen bonds, making them more thermally stable and requiring higher temperatures for denaturation.

Question 3

How is high GC content related to gene regulation?

Answer 3

Many regulatory elements, such as promoters and enhancers, are found in GC-rich regions, which are associated with transcription factor binding sites.

Question 4

What is the relationship between high GC content and coding sequences?

Answer 4

High GC content is frequently observed in essential housekeeping genes and tumor-suppressor genes, indicating its importance for gene functionality.

Question 5

What are CpG islands?

Answer 5

Short stretches of DNA with a high frequency of CG dinucleotides, often found near gene promoters and significant for gene regulation and epigenetic modifications.

In the context of CpG islands, cytosine (C) is more likely to be methylated than guanine (G). This is primarily due to the nature of DNA methylation, which predominantly occurs at the cytosine residues within the CpG dinucleotide context.

Question 6

What challenges do high GC content regions pose for DNA manipulation?

Answer 6

Their increased stability can complicate amplification during PCR, requiring optimized conditions to avoid non-specific binding.

Question 7

How can high GC content be associated with disease?

Answer 7

Mutations or instabilities in GC-rich regions can contribute to genetic disorders.

Question 8

Methylation of CpG island

Answer 8

Methylation of cytosines in CpG islands can impair transcription factor binding and recruit proteins that repress gene expression. Conversely, unmethylated CpG islands are often associated with active transcription

Question 10

The function of CpG island

Answer 10

CpG islands are regions of DNA that are rich in cytosine and guanine nucleotides, often located near gene promoters. They are generally characterized by being less methylated compared to other genomic regions, especially in actively transcribed genes.