December 12

III. Translation
A. The mRNA strand will move out into the cytoplasm and bond to the small subunit of a ribosome.

B.ONced this happens, the 1st codon (AUG) will be joined by the first tRNA molecule (transfer) by its anticodon (UAC) and it will bring in the first amino acid-methionine.

C.Now the large subunit of the ribosome will bond on top of the small subunit with teh mRNA strand attached. The large subunit has 3 areas where activity takes place.

       E (Exit)     P (Peptide)     A (Attach)

  The first codon/anticodon is now in the P Site.

D. Now the second tRNA moves in with its amino acid into the A site bringing its amino acid. The bond between the first tRNA and its amino acid will now break and the first peptide bond will now form between the first two amino acids

E. Now the ribosome will sjhift position so that the first codon is in the E site, second in the p site, and third in the A site. The first tRNA will now "exit" the E site (missing its amino acid) The bond between the second tRNA and its amino acid will now break, and a peptide bond will form between the second and third amino acid brought into the A site by the third tRNA.

F. This process continues until the entire length of the mRNA has passed through the ribosome and a STOP codon (UAA, UAG, UGA) is reached. When this happens a release factor moves into the A site and this terminates the polypeptide sequence.

This process is known as THE CENTRAL DOGMA OF BIOLOGY. This is because all life uses the same 20 amino acids to make their proteins, the smae 64 codons to put those amino acids in order, the same chemicals (DNA, mRNA, rRNA, tRNA) to code for and store the information to make proteins.

Mutation- Any change in the DNA molecule.

I. Point Mutations- mutation happens to a small area. (1-2 base pairs of the DNA) inside a gene.
   A. Deletion- one or more base pairs are removed
   B. Addition- one ore more base pairs are added