Central Dogma DNA=genotype Transcription RNA= the messenger Translation Polypeptide=phenotype

Central Dogma DNA Transcription RNA= the messenger Translation Translation Polypeptide= phenotype

For translation to happen, the messenger RNA goes to the cytoplasm where it is attached to a cellular structure called a ribosome.

Translation : CODON (mRNA) Amino Acid AntiCODON (tRNA) Polypeptide

The structure of tRNA Single strand of RNA Folded back upon itself Held together with H-bonds

The structure of tRNA Amino acid attachment on 3” end Anticodon couples to the mRNA

Code Redundancy Third base in a codon shows "wobble”. First two bases are the most important in reading the code and giving the correct amino acid. The third base often doesn’t matter.

The structure of tRNA

coupling a.acid to the enzyme Enzyme

coupled a. acid joins with P Enzyme Phosphate joins to a.a.Phosphate joins to a.a.

Coupling Enzyme Phosphate joins to a.a. by loosing 2 PPhosphate joins to a.a. by loosing 2 P tRNA bonds to the amino acidtRNA bonds to the amino acid

Coupling Enzyme Phosphate joins to a.a. (for energy)Phosphate joins to a.a. (for energy) tRNA bonds to a.a.tRNA bonds to a.a. enzyme releases “activated amino acid”enzyme releases “activated amino acid”

  TWO subunits to a ribosome

Ribosome Binding Sites: 3

5’ cap Large subunit attaches The mRNA joins to the small ribosomal unit at the 5' untranslated region. This binds to a special binding site on the small ribosomal subunit cap

5’ cap Large subunit attaches The large ribosomal subunit attaches to the small subunit such that the first codon is aligned at the P binding site.

5’ cap Large subunit attaches A tRNA carrrying the amino acid methionine attaches to the start codon (AUG) on the messenger RNA. This inititates elongation.

5’ cap Large subunit attaches Brings together: mRNA tRNA carrying the 1st amino acid 2 subunits of the ribosome

5’ cap Large subunit attaches Attachment of first amino acid carrying tRNA to A binding site. A tRNA and its amino acid attaches to the A binding site.

5’ cap Large subunit attaches Peptide bond formation between the met and the amino acid carried at the A bindiung site. Our polypeptide chain is now: Met -Thr

5’ cap Large subunit attaches Ribosome moves in the 3' direction down the messenger RNA by three bases or one codon shifting the tRNA and polypeptide chain to the P Binding site. The A binding site is open and a vacant tRNA is in the E binding site.

5’ cap Large subunit attaches tRNA ejected from the E binding site.

5’ cap Large subunit attaches Repeat Elongation Step until stop codon encountered..

5’ cap Large subunit attaches Elongation ends with: * Old tRNA ejected from the E Binding site

Elongation of polypeptide chain:

Termination of Translation Stop codon to the A site. release factor (protein) binds to A site -- offers a water molecule (not a.a.)

5’ cap Large subunit attaches The polypeptide chain is at the P site. The stop codon at the A site.

Large subunit attaches A Release factor protein binds to the stop codon at the A binding site.

Large subunit attaches Separation of translation machinary. Polypeptide chain may go to cytoplasm for further processing.

Large subunit attaches Release factor protein initiates separation of polypeptide chain: Met-Thr-His-Asp-Gly

Termination of Translation

mRNA is translated simultaneously by several ribosomes in clusters

NOW WHAT?????? My head is going to explode