Gene Expression

Amino acid

A protein "building block." There are 20. Amino acids float in cytoplasm. Specific tRNA molecules collect specific amino acids, then bring to ribosome. Peptide bonds form between amino acids and a polypeptide chain forms, creating proteins.

Complementary base pairs

A-T and G-C in DNA, A-U and C-G in RNA

Enzyme

A specific type of protein that controls all of the chemical reactions in the body. Can be affected by temperature, pH, poisons etc…

Gene

A section of DNA along a chromosome which codes for a particular protein.

Peptide bond

A bond that forms between two amino acid molecules during protein synthesis, creating a polypeptide chain.

Nucleotide

A 'building block' of DNA or RNA. Consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Polypeptide

A chain of amino acids. One or more forms a functional protein

Protein

An organic molecule made up of amino acids linked together (polypeptide) in a particular order, determined by the DNA sequence.

RNA

Ribonucleic acid, a single stranded nucleic acid that is involved in the synthesis of proteins

Codon

Three bases along an mRNA molecule.

mRNA

Messenger RNA
- RNA polymerase attaches complementary RNA nucleotides to the template strand, forming mRNA molecule. (nucleus)
- Carries a complimentary copy of the DNA to the ribosome for protein synthesis (cytoplasm)

Protein synthesis

The process where the genetic code is used to construct a protein.
Transcription and Translation.

Ribosome

The cell's 'protein factory,' the site for protein synthesis
- Consisting of 2 units of rRNA

rRNA

Ribosomal RNA, this forms part of the structure of a ribosome

Triplet

Three bases along a DNA molecule

Transcription

The process where the template strand of DNA is used to form a strand of mRNA during protein synthesis.

Anticodon

Three bases on a tRNA molecule

Deletion mutation

A mutation that involves the loss of one or more bases, causing a frame shift

Frame shift

Occurs when one or more bases are inserted or deleted in the DNA, changing how the triplets are read

Gametic mutation

A mutation occurring in gametes (sex cells) that can be by offspring if the sperm or egg with the mutation is the one that is fertilized/fertilizing

Insertion mutation

A mutation in which there is an addition of an extra base, or bases in the DNA strand which causes a frame shift to occur

Metabolic block

The failure of a reaction on a metabolic pathway due to a non-functional enzyme

Mutagen

A physical or chemical agent that changes the DNA of an organism or increases the frequency of mutations

Mutation

A random and permanent change in the DNA of a cell

Redundant/degenerate code

Where an amino acid may be coded for by more than one mRNA codon

RNA polymerase

The enzyme that joins new nucleotides onto the template strand of DNA to make mRNA

Template strand

The strand of DNA that is copied (transcribed) when mRNA is produced

Base substitution mutation

A mutation where one base in DNA is substituted for another

Coding strand

The strand of the DNA molecule that stores the genetic code for making a protein

Metabolic pathway

A series of enzyme controlled chemical reactions occurring within a cell. In a metabolic pathway, a starting chemical (substrate), is converted by a series of different enzymes into a final product

Somatic mutation

A mutation that occurs in a body cell, these can not be inherited by the offspring and will only affect the individual with the mutation

Recessive condition

A genetic condition arising from a mutation that produces a recessive allele. Both parents must carry the allele for it to be expressed in the offspring

Phenotype

The physical expression of the genotype/what the trait looks like

Dominant condition

A genetic condition arising from a mutation that produces a dominant allele. Only one copy of the allele is needed for it to be expressed in the phenotype

Gene mutation

A change in the base sequence of a gene which results in a new allele. May involve base substitution, insertion, or deletion

Genotype

The genetic make up of an organism/the two alleles it has for a particular gene