30.1 - Do First: Protein Synthesis Review

The mRNA (or pre-mRNA) contains introns and exons. Splicing removes the introns and joins the exons together.

The mRNA exits the nucleus through a nuclear pore. Once in the cytoplasm, it associates with a ribosome.

Free RNA nucleotides attach to the exposed DNA bases and RNA polymerase joins them together to form mRNA.

Inside the nucleus, DNA is unzipped and RNA polymerase initiates transcription at a promoter sequence.

Each tRNA carries an amino acid - as the tRNA molecules are brought into alignment, the adjacent amino acids bond.

When a STOP codon is reached, the polypeptide is finished - some proteins are just 1 polypeptide while others have multiple polypeptides.

The tRNA detaches from its amino acid and leaves the ribosome.

The mRNA exits the nucleus through a nuclear pore. Once in the cytoplasm, it associates with a ribosome.

Transfer RNA (tRNA) molecules with the correct anticodons attach to the codons in the mRNA strand.

The mRNA strand is shifted by one codon and new tRNA molecules attach, building up an amino acid chain ( a polypeptide).