Introduction to Genetics and Genomics: DNA Methylation

Flashcards on DNA Methylation

DNA Methylation

The process whereby nucleotides become methylated.

Epigenetics

The study of heritable gene expression which doesn't alter the underlying gene sequence.

Nucleotide

Consists of a phosphate group, nitrogenous base, and pentose sugar; the building block of DNA.

Nitrogenous Base

A component of DNA with four variants: Cytosine, Thymine, Guanine, and Adenine.

Pyrimidines

Nitrogenous bases Cytosine and Thymine, which contain a single 6-membered nitrogen-containing ring structure.

Purines

Nitrogenous bases Guanine and Adenine, which contain a double (5 and 6) membered nitrogen-containing ring structure.

Phosphodiester Bonds

The bonds that form the sugar-phosphate backbone between nucleotides in DNA strands.

Complementary Base Pairing

The specific pairing of nitrogenous bases in DNA: Adenine with Thymine and Guanine with Cytosine.

Nucleosomes

Octamer of histone proteins (core), 146bp of DNA wrapped 1.65x around the core, and a histone linking protein.

Chromatin

Multiple solenoid turns stack close to one another, compacting the DNA further

Heterochromatin

Tightly packed nucleosomes associated with 'low' transcription or transcriptional silencing.

Euchromatin

Loosely packed nucleosomes associated with 'high' transcription or transcriptional activity.

Methylation

An epigenetic modification where a methyl group is added, often affecting gene expression.

CpG Sites

Regions within DNA where DNA methylation occurs, specifically at cytosine bases followed by guanine.

CpG Islands (CGIs)

Stretches of DNA (200-2000 bp) with a Guanine : Cytosine ratio >50% and a CpG Observed : Expected ratio >60%.

DNMT (DNA Methyl Transferase)

Enzymes involved in DNA methylation, including DNMT1, DNMT3a, and DNMT3b.

Methylome

The state of methylated and unmethylated cytosine throughout the genome.

Gene Expression

Transcription of DNA into mRNA and translation into a functional product.