Why is the CG dinucleotide sequence so vulnerable to mutation?

CpG dinucleotides mutate at a high rate because cytosine is vulnerable to deamination, cytosines in CpG dinucleotides are often methylated, and deamination of 5-methylcytosine (5mC) produces thymidine. Previous experiments have shown that DNA melting is the rate-limiting step in cytosine deamination.

Which DNA has dinucleotide repeats?

Microsatellites. Microsatellites, also referred to as “short tandem repeats” (STRs), are generally dinucleotide repeats found throughout the genome of eukaryotic and prokaryotic organisms.

Why is dinucleotide CG underrepresented in the human genome?

The CG dinucleotides are known to be deficient in the human genome, due to a high mutation rate from 5-methylated CG to TG and its complementary pair CA. Meanwhile, many cellular functions rely on these CG dinucleotides, such as gene expression controlled by cytosine methylation status.

How many CPGS are in the human genome?

The human genome contains ∼30,000 CpG islands (CGIs), long stretches (0.5–2 kb) of DNA with unusually elevated levels of CpG dinucleotides. Many occur at genes’ promoters, and their DNA nearly always remains unmethylated.

What are Dinucleotides?

Definition of dinucleotide : a nucleotide consisting of two units each composed of a phosphate, a pentose, and a nitrogen base.

What are multigene families?

A multigene family is a group of genes that have descended from a common ancestral gene and therefore have similar functions and similar DNA sequences. A group of related multigene families is sometimes called a supergene family.

Is mutation reversible?

Mutation can range from a change in a single nucleotide to the loss or addition of a whole fragment. The process of genetic mutations is reversible, and once occurred, it cannot be reverted to the normal stage.

What are reverse mutations?

Reverse mutation, also called reversion, denotes any mutational process or mutation that restores the wild-type phenotype to cells already carrying a phenotype-altering forward mutation. Forward mutations confer a gene sequence and phenotype different from that conferred by the wild-type gene.

What are examples of dinucleotide?

Phrases Containing dinucleotide

  • flavin adenine dinucleotide.
  • nicotinamide adenine dinucleotide.
  • nicotinamide adenine dinucleotide phosphate.

Does methylation increase gene expression?

Evidence suggests that DNA methylation of the gene body is associated with a higher level of gene expression in dividing cells (Hellman and Chess, 2007; Ball et al, 2009; Aran et al, 2011).