Biology - Gene Expression

NCEA level 2

Gene Expression

The process where a gene's information is used to create a functional product, most often a protein.

Protein

A large and complex molecule made of one or more long chains of amino acids linked together.

Protein synthesis

The process of making a protein (or polypeptide) from the genetic code in DNA.

Ribosome

A non-membrane-bound organelle responsible for protein synthesis (translation). It acts as a cellular "factory" that reads genetic instructions from messenger RNA (mRNA) and links specific amino acids together to form a polypeptide chain (protein). 

Promoter Region

A specific sequence of DNA located upstream (before) a gene where the enzyme RNA polymerase and transcription factors bind to initiate the process of transcription.

Coding region

The specific portion of a gene that contains the instructions to produce a protein. 

Terminator region

A specific sequence of nucleotides in the DNA located at the end (downstream) of a gene or transcription unit. Its primary function is to signal the end of the transcription process.

Methionine

The amino acid coded for by the start codon (AUG). 

Frameshift

An insertion or deletion of nucleotides (DNA bases) that is not a multiple of three, which disrupts the normal triplet reading frame of the genetic code.

Missense mutation

a type of gene mutation where a single base pair change in the DNA sequence results in a different amino acid being incorporated into the resulting protein during translation. 

Nonsense mutation

A type of point mutation in a DNA sequence that changes a codon which originally coded for an amino acid into a premature stop codon.

Same sense mutation

A base substitution mutation in the DNA sequence that does not result in a change to the amino acid sequence of the resulting protein. 

Degeneracy / Redundancy

Degeneracy refers to the feature of the genetic code where more than one codon (a sequence of three DNA or mRNA bases) can code for the same amino acid. 

Metabolism

The sum of all chemical reactions in a living organism, which occur in a series of enzyme-controlled reactions called metabolic pathways.

Substrate

The specific molecule or substance upon which an enzyme acts during a biochemical reaction. 

Catalyst

A substance that increases the rate of a chemical reaction by providing an alternative pathway with a lower activation energy.

Environmental factor

A variable in an organism's surroundings that can affect its phenotype, or observable characteristics, without changing its genotype (DNA sequence).

Gene regulation

The process of controlling which genes are expressed in a cell, determining when, where, and how much protein is made.

Metabolic pathway

A series of enzyme-controlled chemical reactions within a cell, where the product of one reaction becomes the starting material for the next.

Peptide bond

The covalent bond that forms between two amino acids during a condensation reaction. 

Amino acid

The basic building block (monomer) of proteins. 

Triplet

A sequence of three consecutive nucleotide bases on a DNA strand.

Codon

A sequence of three consecutive nucleotides on an mRNA strand that codes for a specific amino acid or a signal to stop protein synthesis.

Anticodon

A sequence of three nucleotides (bases) on a transfer RNA (tRNA) molecule that is complementary to a specific messenger RNA (mRNA) codon. 

RNA

A single-stranded nucleic acid molecule that plays a critical role in protein synthesis.

Transcription

The process of rewriting a gene's DNA sequence into a messenger RNA (mRNA) molecule, which happens in the nucleus.

Translation

The process where a ribosome uses the information from a messenger RNA (mRNA) sequence to create a polypeptide chain, which then folds into a functional protein.