Reproduction key terms

Human genome

The complete set of genetic material in a human cell, comprising all genes and non‑coding DNA, which can be analysed to identify disease‑linked genes, understand inherited disorders and trace human migration patterns.

Genetic variation

Differences in DNA sequence between individuals that can influence the presence of disease‑linked alleles, affect inherited disorder risk and provide evidence for patterns of human migration.

nucleotide

The basic building block of DNA, consisting of a sugar, a phosphate group, and one of four bases (adenine, cytosine, guanine, or thymine).

polymer

A large molecule composed of repeating structural units, in this case, nucleotides that form the DNA strand.

nucleotide

A nucleotide is the basic building block of DNA, consisting of a sugar, a phosphate group, and one of four nitrogenous bases (adenine, cytosine, guanine, or thymine).

double helix

The double helix is the structure of DNA, formed by two strands of nucleotides twisted around each other, with bases pairing specifically (A with T and C with G).

DNA bases

The four nitrogenous bases that make up DNA: adenine (A), cytosine (C), guanine (G) and thymine (T).

Nucleotide

The basic building block of DNA, consisting of a sugar, a phosphate group and one of the four bases (A, C, G, or T).

triplet code

In DNA structure (biology only), triplet code means the specific Unit 4.6 idea used to answer this objective: students must explain that a sequence of three bases codes for a particular amino acid. Keep the term curriculum-specific by applying this boundary: DNA is the molecule; a gene is a functional section of that molecule. Do not use triplet code as a vague inheritance word; link it to Reproduction and explain the exact role it plays in AQA GCSE Biology.

amino acid

The building blocks of proteins, each coded for by a specific sequence of three bases in DNA.

bases

The building blocks of DNA, consisting of adenine (A), cytosine (C), guanine (G), and thymine (T), which determine the genetic code.

amino acid

The organic compounds that serve as the building blocks of proteins, with their sequence determined by the order of bases in DNA.

sugar

The five‑carbon backbone component of a nucleotide that links to phosphate groups and bases in the DNA strand.

phosphate

The negatively charged group that connects adjacent sugars, forming the sugar‑phosphate backbone of DNA.

DNA double helix

The three‑dimensional shape of DNA, formed by two complementary strands winding around each other.

nucleotide

The basic building block of DNA, consisting of a sugar, a phosphate group and one of four bases (A, C, G, T).

protein synthesis

The process by which cells use ribosomes to assemble amino acids into proteins based on the sequence of nucleotides in mRNA.

ribosome

A cellular structure that facilitates the translation of mRNA into a polypeptide chain during protein synthesis.

DNA structure

The arrangement of nucleotides in a double‑helical polymer, where complementary bases (A with T, C with G) pair to form a stable sequence that determines the order of amino acids in a protein.

Amino acid sequence

The linear order of amino acids encoded by a gene’s DNA sequence, which dictates the protein’s shape and function.

Complementary base pairing

The specific matching of nitrogenous bases in DNA, where cytosine (C) pairs with guanine (G) and thymine (T) pairs with adenine (A), forming the double‑helix structure.

Base pairing rule

The principle that dictates which bases pair together in DNA: C↔G and A↔T, ensuring accurate replication and transcription of genetic information.

mutation

In DNA structure (biology only), mutation means the specific Unit 4.6 idea used to answer this objective: students must explain (HT only) how a mutation may change the protein synthesised by a gene. Keep the term curriculum-specific by applying this boundary: DNA is the molecule; a gene is a functional section of that molecule. Do not use mutation as a vague inheritance word; link it to Reproduction and explain the exact role it plays in AQA GCSE Biology.

protein synthesis

The process by which cells use genetic information to produce proteins, which are essential for various cellular functions.

Coding DNA

The portion of a gene’s DNA sequence that is transcribed into mRNA and translated into a protein, determining the amino acid sequence of that protein.

Phenotype

The observable characteristics or traits of an organism that result from the interaction of its genotype with the environment.

Non‑coding DNA

Regions of the genome that do not code for proteins but can influence gene expression and thereby affect an organism’s phenotype.

Gene expression regulation

The processes by which variations in non‑coding DNA alter the level, timing or location of gene transcription, ultimately influencing the phenotype.

mRNA

Messenger RNA, the RNA copy of a gene’s coding sequence that carries the genetic message from DNA to the ribosome.

tRNA

Transfer RNA, the adaptor RNA that brings specific amino acids to the ribosome during protein synthesis.