A1.2 - Nucleic Acids

Nucleic Acid

A type of biological macromolecule that includes DNA and RNA, made of chains of nucleotides.

Nucleotide

The basic building block of nucleic acids, composed of a sugar, a phosphate group, and a nitrogenous base.

Deoxyribonucleic Acid (DNA)

The genetic material of all living organisms, typically double-stranded and made up of nucleotides containing the sugar deoxyribose.

Ribonucleic Acid (RNA)

A nucleic acid that is usually single-stranded and plays a role in coding, decoding, regulation, and expression of genes.

Sugar–Phosphate Backbone

The alternating chain of sugar and phosphate groups that makes up the structural framework of nucleic acids.

Complementary Base Pairing

A key feature of nucleic acids, where adenine pairs with thymine (or uracil in RNA) and guanine pairs with cytosine.

Purines

Nitrogenous bases that have a two-ring structure, which includes adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases that have a one-ring structure, which includes cytosine (C), thymine (T) and uracil (U).

Polymerization

The process of joining monomers, such as nucleotides, to form a polymer like DNA or RNA.

Antiparallel Strands

Refers to the opposite orientation of the two strands of DNA, with one running 5' to 3' and the other running 3' to 5'.

Histone

A protein that DNA wraps around to form nucleosomes, which help package the DNA in the nucleus.

Hershey–Chase Experiment

An experiment that provided evidence that DNA, not protein, is the genetic material by using radioactive labeling.

Chargaff's Rules

The observation that in DNA, the amount of adenine equals thymine and the amount of cytosine equals guanine.

Gene Expression

The process by which the information in a gene is used to synthesize a functional gene product, usually proteins.

DNA Replication

The process of making a copy of DNA before cell division, ensuring each new cell has an identical copy of the DNA.

Double Helix

The structure of DNA, consisting of two strands wound around each other, with complementary bases facing inward.

RNA World Hypothesis

A theory suggesting that early life forms may have relied solely on RNA for genetic information before the evolution of DNA.

Nucleosome

A structural unit of a eukaryotic chromosome, consisting of a segment of DNA wrapped around a core of histone proteins.

Triplet Codon

A set of three consecutive nucleotides in DNA or RNA that encode a specific amino acid.

Base Sequence

The order of nucleotide bases in a DNA or RNA molecule that determines genetic information.