1. Protein synthesis Transcription and translation

2. fromtoto make up also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes DNARibosomeRibosomes

3. Transcription RNA DNA RNA polymerase Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only)

4. mRNA Primary transcript will be edited –Introns are removed –Segments may be deleted or rearranged according to instructions from other regions of DNA Final version of mRNA get a “cap” and “tail” to mark it as complete. Now it can leave the nucleus.

5. The Genetic Code Groups of 3 DNA nucleotides are called triplets and each represents an amino acid or an instruction to “start” or “stop”. –There are 4 nucleotides, so how many possible combinations of 3 are there? –How does this relate to the number of amino acids? –The code is redundant.

6. The genetic code When the code is transcribed to mRNA, the groups of 3 nucleotides are called codons. Each codon represents one amino acid or a start (AUG) or stop. –Multiple codons may mean the same thing.

7. The genetic code

8. The Genetic Code 1.Find the 1 st base along the left side – look only in that row. 2.Find the 2 nd base along the top – look only in that column. 3.Find the 3 rd base along the right side in the row of the 1 st base.

9. Translation Messenger RNA Messenger RNA is transcribed in the nucleus. Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. Ribosome Methionine Phenylalanine tRNA Lysine mRNA

10. Translation, continued The Polypeptide “Assembly Line” The ribosome joins the two amino acids— methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. Ribosome Translation direction Lysine tRNA Ribosome Growing polypeptide chain mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain.