F215 - Cellular Control

Transcription

• DNA molecule unzips and DNA helicase breaks the hydrogen bonds

• RNA nucleotides match up with the complementary base (Uracil instead of thymine)

• Base pairings bond in a condensation reaction performed by RNA polymerase

• The enzyme moves along until it reaches the end of a gene (stop codon)

• mRNA is released and leaves the nucleus and travels to a ribosome

Translation

• Three bases on mRNA are called a codon they code for an amino acid, start or stop

• Translation requires transfer RNA - tRNA

• Each tRNA has three exposed bases at one end which is called an anticodon

• This anticodon is required for complementary base pairing with a codon of mRNA

• The other end has an amino acid binding site

• Each anticodon can only bind one specific amino acid

• tRNA transferases load the amino acids to the specific tRNA in the cytoplasm (different type of transferase for each tRNA)  

Building the polypeptide

• mRNA is held in…