Ribosomes and protein synthesis lecture 1

Ribosome

A particle composed of rRNAs and ribosomal proteins that catalyses the synthesis of protein using information provided by mRNA.

Codon

A sequence of three nucleotides in a DNA or mRNA molecule that represents the instruction for incorporation of a specific amino acid into a growing polypeptide chain.

Anticodon

A sequence of three nucleotides in a transfer RNA molecule that is complementary to a three-nucleotide codon in a messenger RNA molecule.

Aminoacyl-tRNA synthetase

Enzyme that attaches the correct amino acid to a tRNA molecule to form an aminoacyl-tRNA.

Translation

Process by which the sequence of nucleotides in an mRNA molecule directs the incorporation of amino acids into a protein. Occurs on a ribosome.

Transfer RNA (tRNA)

Set of small RNA molecules used in protein synthesis as an interface between mRNA and amino acids. Each type of tRNA molecule is covalently linked to a particular amino acid.

Proteosome

Large protein complex in the cytosol with proteolytic activity that is responsible for degrading proteins that have been marked for destruction by ubiquitylation or some other means.

Ribozyme

An RNA molecule with catalytic activity.

Open reading frame

A continuous nucleotide sequence free from stop codons in at least one of the three reading frames (and thus with the potential to code for a protein).

mRNA

Messenger RNA; carries the coding sequences for protein synthesis and are called transcripts – carries message from DNA to cytoplasm.

Protein synthesis

Biological process that involves two main stages: Transcription (DNA copied into strand of mRNA) and Translation (formation of a chain of amino acids).

Chaperones

Proteins that assist in the folding of newly synthesized proteins.

Start codon

A specific codon that signals the start of translation, recognized by initiator tRNA.

Stop codon

A specific codon that signals termination of the translation process.

rRNA (ribosomal RNA)

Forms the core of the cell's ribosomes.

Polypeptide chain

A chain of amino acids linked together by peptide bonds, formed during protein synthesis.

Peptide bond

The chemical bond that connects amino acids together in a protein.

Reading frame

The way nucleotides in mRNA are divided into codons for translation.

Elongation factors

Proteins that help in the elongation phase of protein synthesis by driving the reaction using GTP hydrolysis.

RNA polymerase

Enzyme that synthesizes RNA from a DNA template.

Promoter region

A specific area where RNA polymerase and transcription factors bind to facilitate transcription.

Poly-A tail

A sequence of adenine nucleotides added to the 3' end of an mRNA molecule; signals that mRNA is ready to leave the nucleus.