Gene Expression

Flashcards

DNA

Deoxyribonucleic acid, a molecule that stores the genetic instructions needed for an organism's development and functioning.

RNA

Ribonucleic acid, a usually single-stranded nucleic acid involved in using genetic information to make proteins.

Nucleotide

The building block of DNA and RNA, consisting of a phosphate group, a sugar and a nitrogenous base.

Double helix

The twisted ladder-like structure formed by two DNA strands.

Deoxyribose

The five-carbon sugar found in DNA nucleotides.

Ribose

The five-carbon sugar found in RNA nucleotides.

Nitrogenous base

A nitrogen-containing molecule that forms part of a nucleotide and carries genetic information.

Complementary base pairing

The specific pairing of nitrogenous bases, where A pairs with T in DNA, A pairs with U in RNA, and C pairs with G.

Antiparallel

Describes two DNA strands that run in opposite directions.

Hydrogen bonds

Weak chemical bonds that hold complementary nitrogenous bases together in DNA.

mRNA (messenger RNA)

A type of RNA that carries genetic instructions copied from DNA to a ribosome for protein synthesis.

tRNA (transfer RNA)

A type of RNA that carries specific amino acids to the ribosome during translation.

rRNA (ribosomal RNA)

A type of RNA that forms part of the ribosome and helps join amino acids together during protein synthesis.

Genetic code

The system where sequences of three bases in mRNA determine which amino acids are added to a protein.

Codon

A sequence of three bases on mRNA that codes for a specific amino acid or a stop signal.

Anticodon

A sequence of three complementary bases on tRNA that pairs with an mRNA codon.

Amino acid

A small organic molecule that acts as a building block of proteins.

Polypeptide

A chain of amino acids joined together by peptide bonds.

Peptide bond

A chemical bond that joins two amino acids together.

Start codon

The mRNA codon AUG that signals the beginning of translation and codes for methionine.

Stop codon

An mRNA codon (UAA, UAG or UGA) that signals the end of translation.

Reading frame

The way a nucleotide sequence is divided into groups of three bases called codons.

Protein synthesis

The process where genetic information in DNA is used to produce a polypeptide chain, through transcription and translation.

Transcription

The process of copying genetic information from a DNA template strand into a complementary mRNA molecule.

RNA polymerase

An enzyme that joins RNA nucleotides together to produce an mRNA strand during transcription.

DNA template strand

The DNA strand that is used as a guide to produce a complementary mRNA sequence.

Translation

The process where ribosomes read mRNA codons and join amino acids together to produce a polypeptide chain.

Ribosome

A cell structure made of rRNA and proteins where translation and protein synthesis occur.

Nuclear pore

A small opening in the nuclear membrane that allows substances such as mRNA to move between the nucleus and cytoplasm.

Rough endoplasmic reticulum

A network of membranes covered in ribosomes where some proteins are made and processed.

Protein

A molecule made of one or more folded polypeptide chains that performs specific functions in an organism.

Protein structure

The specific arrangement and three-dimensional shape of a protein, determined by its amino acid sequence and interactions between amino acids.

Protein folding

The process where a polypeptide chain folds into a specific three-dimensional shape needed for its function.

Structural protein

A protein that provides strength, support and structure to cells and tissues.

Enzyme

A biological catalyst, usually a protein, that speeds up chemical reactions without being used up.

Functional protein

A protein that performs a particular job in an organism, such as catalysing reactions or transporting substances.

Mutation

A permanent change in the DNA nucleotide sequence that can create a new allele.

Mutagen

An agent that increases the likelihood of mutations occurring in DNA.

Substitution mutation

A mutation where one nucleotide is replaced by another nucleotide in the DNA sequence.

Insertion mutation

A mutation where one or more nucleotides are added to the DNA sequence.

Deletion mutation

A mutation where one or more nucleotides are removed from the DNA sequence.

Point mutation

A mutation that affects a single nucleotide or base pair in DNA.

Frameshift mutation

A mutation caused by the insertion or deletion of nucleotides in a number that is not a multiple of three, changing the reading frame of the genetic code.

Silent mutation

A mutation that changes a DNA base but does not change the amino acid produced.

Missense mutation

A mutation that changes a codon so that a different amino acid is produced.

Nonsense mutation

A mutation that changes a codon into a stop codon, causing translation to end early.

Amino acid sequence

The specific order of amino acids in a polypeptide chain.

Functional change

A change in how well a protein performs its normal role, potentially caused by a change in its structure.

Metabolism

The collection of all chemical reactions that occur within an organism's cells.

Metabolic pathway

A series of chemical reactions in a cell where the product of one reaction becomes the substrate for the next reaction.

Substrate

The starting substance that an enzyme acts on during a chemical reaction.

Product

The substance formed as a result of a chemical reaction.

Intermediate

A substance produced during one step of a metabolic pathway that is used in a later step.

Blocked metabolic pathway

A metabolic pathway where a reaction is slowed or stopped because an enzyme is missing or not functioning correctly.

Gene-enzyme relationship

The relationship where genes contain instructions for making proteins, including enzymes that control reactions in metabolic pathways.

Environment

The external conditions and surroundings that can influence an organism's development and characteristics.

Environmental factor

An external condition, such as temperature, light, water or nutrition, that can influence gene expression or an organism's phenotype.

Gene expression

The process where information in a gene is used to produce a functional product, such as a protein.

Phenotype

The observable characteristics of an organism resulting from interactions between its genotype and environment.

Genotype

The genetic information or combination of alleles an organism possesses.

Gene regulation

The control of when, where and how much a particular gene is expressed.