Ribonucleic acid and Codons

RNA

A polynucleotide acid that is structurally similar to DNA but withe three major exceptions. The sugar is ribose. Uracil is used instead on thymine. Most of theses acids are single stranded.

mRNA

This carries the complement of a DNA sequence. Transports information from the nucleus to the ribosomes for protein synthesis. IT is made from ribonucleotides complementary to the template strand.

tRNA

A small RNA molecule found in the cytoplasm. It assist in the translation of mRNA’s nucleotide code into a sequence of amino acids by bringing amino acids coded for the mRNA sequence to the ribosomes for protein synthesis.

anticodon

A trinucleotide sequence located at one end of a tRNA molecule, which is complementary to a corresponding codon in a mRNA sequence.

charged tRNA

Contains a charged chemical bond with an amino acid. It transports the amino acid to the ribosome where it is incorporated into the polypeptide chain during translation.

rRNA

Functions as an integral part of the ribosomal machinery used during protein assembly in the cytoplasm.

transcription

The process through which information coded in the sequence of DNA is used to direct the synthesis of a strand of RNA.

introns

Are non-coding sequences of DNA within a gene that are removed from the final RNA transcript through a process called splicing.

exons

Are the nucleotides that forms the final RNA produced by that gene, after introns are removed by RNA splicing. They will exit the nucleus as part of the mRNA.

Codons

Are three nucleotide sequences on the mRNA that correspond to a specific amino acid.

stop codons

UAA/UGA/UAG. They instruct the ribosome to stop translation.

Translation

The process through which mRNA codons are translated into a sequence of amino acids.

Initiation

Process by which the ribosome binds to the mRNA start codon and the first tRNA.

Elongation

Amino acids are brought to the ribosome by tRNA’s and are linked together to form a chain.

start codon

The first codon in mRNA transcript that a ribosome translates.

A site

A binding site for charged tRNA molecules during protein synthesis.

P site

The second binding site for tRNA in the ribsome.

E site

Where the now uncharged tRNA briefly pauses before it is expelled from the ribosome, to be recharged.

translocation

Process by which the ribosome advances 3 nucleotides along the mRNA in the 5’ to 3’ direction.

termination

The finished polypeptide is released to go and do its job in the cell.

Cleavage

Where certain amino acid sequences are removed from the chain or addition, where biomolecules are added to the peptide.

phosphorylation

Addition of a phosphate group.

carboxylation

Addition of a carboxylic acid groups.

glycosylation

Addition of oligosaccharides (sugars), completed in the Golgi body.

prenylation

Addition of lipids groups, allowing for incorporation of the protein into membranes.