NCEA Level 2 Gene Expression

DNA

deoxyribonucleic acid

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

Uracil

a nitrogen-containing base found in RNA (but not in DNA)

Nucelotide

sugar, phosphate group, base

Transcription

the organic process whereby the DNA sequence in a gene is copied into mRNA

RNA polymerase

Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription

nuclear pores

holes in the nuclear envelope that allow materials to pass in and out of the nucleus

Ribosomes

site of protein synthesis

Codon

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid

Anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

amino acids

building blocks of proteins

Polypeptide

long chain of amino acids that makes proteins

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

Peptide bond

covalent bond formed between amino acids

primary structure of protein

the amino acid sequence of the polypeptide chain

secondary structure of protein

protein structure is formed by folding and twisting of amino acid chain (alpha helix or beta sheets).

tertiary structure of protein

protein structure is formed when the twists and folds of the secondary structure fold again to from a larger 3D structure

quaternary structure of a protein

results when a protein consists of multiple polypeptide chains

stop codon

codon that signals to ribosomes to stop translation

codon table

shows all possible codons & the amino acid each codes for

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

Gene

sequence of DNA that codes for a protein and thus determines a trait

Base pairing (DNA)

the nearly perfect fit between A-T and G-C nucleotides

Base pairing (RNA)

A -U, C - G

Protein

An organic compound that is made of one or more chains of amino acids and that is a principal component of all cells (polypeptide)

Disulphide bonds

Where two cysteine amino acids are found together, a strong double bond (S=S) is formed between the sulfur atoms within the cysteine monomers

Phenotype

physical characteristics of an organism

Environmental factors

Factors that change the phenotype of an organism but not the genotype (e.g. temperature, wind, food).

Mutagen

A chemical or physical agent that interacts with DNA and causes a mutation.

Mutation

a permanent change in the base sequence of DNA

substitution mutation

Mutation in which a single base is replaced, potentially altering the amino acid

deletion mutation

a change in the base sequence of a gene that results from the loss of one or more base pairs in the DNA

insertion mutation

the addition of one or more nucleotide base pairs into a DNA sequence

frameshift mutation

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

Beneficial mutations

mutations that can release altered proteins that may be helpful to an organism in a changing environment

Harmful mutations

These mutations are harmful because, by altering the DNA sequence, they upset the structure and function of the protein they code for, producing a disorder in the organism that significantly lowers its survival and reproductive capabilities

Silent mutations

have no effect on the amino acid produced by a codon because of redundancy in the genetic code

protein synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

Gene expression

information from one gene is used to synthesize a functional protein / the whole process of transcription and translation - including protein folding and any post-translational modifications.