DNA

DNA

A two-stranded molecule that forms a double helix, consisting of nucleotides.

Nucleotide

The building block of DNA, composed of a nitrogenous base, deoxyribose sugar, and phosphate group.

Purine

A type of nitrogenous base, which includes adenine and guanine.

Pyrimidine

A type of nitrogenous base, which includes thymine and cytosine.

Hydrogen bonds

Weak attractions that can form between complementary nitrogenous bases in DNA.

Double helix

The helical structure formed by the two strands of DNA.

Antiparallel strands

The orientation of DNA strands running in opposite directions.

Stacking of bases

The cumulative effect of van der Waals forces stabilizing DNA's structure through planar base alignment.

Point Mutation

A mutation that changes the identity of a single base.

Transition Mutation

A mutation where a pyrimidine is swapped for another pyrimidine, or a purine for another purine.

Transversion Mutation

A mutation where a pyrimidine is swapped for a purine or vice versa.

Single-Nucleotide Polymorphism (SNP)

A variation at a single DNA position among individuals that can affect traits and disease susceptibility.

Silent Mutation

A mutation that does not affect protein function.

Missense Mutation

A mutation resulting in an observable change in protein function.

Nonsense Mutation

A mutation that introduces a premature stop codon, creating a nonfunctional protein.

Indel

Insertion or deletion of a base in a DNA sequence.

Frameshift Mutation

An indel that is not divisible by three, causing a shift in the reading frame of the gene.

Tautomeric shifts

Changes in the structure of DNA bases that can lead to base mispairing during replication.

A-DNA

A form of DNA that is partially dehydrated with base pairs tilted and an increased diameter.

Z-DNA

A slimmer, left-handed form of DNA with a zigzag formation.

DNA Supercoiling

The twisting of DNA that allows for compact storage and gene regulation.

Underwound DNA

DNA with fewer turns than normal, resulting in negative supercoiling.

Overwound DNA

DNA with more turns than normal, resulting in positive supercoiling.

Nucleoid

An irregularly shaped region in prokaryotic cells housing the chromosomal DNA.

Nucleoid-associated proteins

Positively charged proteins that help organize and stabilize DNA in prokaryotes.

Chromatin

The complex of DNA and proteins in eukaryotic cells that forms chromosomes.

Histone

Basic proteins that bind to DNA and help form nucleosomes.

Histone Fold

A structural motif in histones consisting of three alpha helices and two loops.

Histone modifications

Covalent modifications of histone tails that can regulate gene expression.

Acetylation

A type of histone modification that impacts gene expression by altering chromatin structure.

Methylation

A modification of histones that can influence gene expression and chromatin accessibility.

Phosphorylation

A histone modification that can impact protein function and chromatin state.

Ubiquitination

A modification of histones that tags them for degradation or alters chromatin structure.

Epigenetic modifications

Chemical changes in DNA or histones that affect gene expression without altering the DNA sequence.

Van der Waals forces

Weak intermolecular forces that stabilize DNA through base stacking.

Spontaneous deamination

The natural deamination of bases in DNA that can lead to mutations.

Ionizing radiation

A type of radiation that can cause damage to DNA.

Cations

Positively charged ions that can shield negative charges in DNA.

Negative charge of DNA

The overall charge of DNA that necessitates protection from destabilizing interactions.