1. PROTEIN SYNTHESIS PROTEIN SYNTHESIS Section 12.3

2. How your cell makes (“synthesizes”) proteins General steps:General steps: DNA  RNA  Protein Occurs in 2 phasesOccurs in 2 phases: 1. Transcription (DNA  RNA) – occurs in the nucleus 2. Translation (RNA  Protein) – occurs on the ribosome in the cytoplasm

3. DNA  RNA  Protein

4. RNADNA RNA is DIFFERENT from DNA RNAsugar ribose 1.RNA has a sugar ribose DNAsugar deoxyribose DNA has a sugar deoxyribose RNAuracil (U) 2.RNA contains uracil (U) DNAthymine (T) DNA has thymine (T) RNAsingle-stranded 3.RNA molecule is single-stranded DNAdouble-stranded DNA is double-stranded

6. 3 types of RNA A.messenger RNA (mRNA) B.transfer RNA (tRNA) C.ribosomal RNA (rRNA)

7. mRNA – the “Messenger” Carries instructions from DNA to the ribosome. Gives the ribosome the “recipe” for making a specific protein

8. rRNA Part of the structure of a ribosome Helps in protein production tRNA “go-getter” Gets the right parts (amino acids) to make the right protein according to mRNA instructions

10. Phase 1: Transcription mRNA is produced by copying part of DNA into a complementary sequence of RNA Occurs inside the nucleus because DNA CANNOT leave the nucleus

11. Question: RNADNAWhat would be the complementary RNA strand for the following DNA sequence? GCG TAT

12. ANSWER: GCG TATDNA: GCG TAT RNA: CGC AUA

13. CODONS Bases are read in groups of 3, called codons. Each codon stands for 1 amino acid.

14. DNA: TAC CTT GTG CAT GGG ATC mRNA AUG GAA CAC GUA CCC UAG A.A MET G.A HIS VAL PRO STOP

15. Another RNA Chart

16. PHASE 2: Translation - making proteins -mRNA lays across the ribosome -bases are read one CODON (3 bases) at a time -tRNA molecules with complementary ANTICODONS deliver the appropriate amino acid to the ribosome -amino acids are linked together in a long chain to form a protein (“polypeptide”

17. PHASE 2: Translation - making proteins 3 Steps: 1.Initiation 2.Elongation 3.Termination

18. Translation

19. Initiation mRNA AUGCUACUUCG 2-tRNA G aa2 AU A 1-tRNA UAC aa1 anticodon hydrogen bonds codon

20. mRNA AUGCUACUUCG 1-tRNA2-tRNA UACG aa1 aa2 AU A anticodon hydrogen bonds codon peptide bond 3-tRNA GAA aa3 Elongation

21. mRNA AUGCUACUUCG 1-tRNA 2-tRNA UAC G aa1 aa2 AU A peptide bond 3-tRNA GAA aa3 Ribosomes move over one codon (leaves)

22. mRNA AUGCUACUUCG 2-tRNA G aa1 aa2 AU A peptide bonds 3-tRNA GAA aa3 4-tRNA GCU aa4 ACU

23. mRNA AUGCUACUUCG 2-tRNA G aa1 aa2 AU A peptide bonds 3-tRNA GAA aa3 4-tRNA GCU aa4 ACU (leaves) Ribosomes move over one codon

24. mRNA GCUACUUCG aa1 aa2 A peptide bonds 3-tRNA GAA aa3 4-tRNA GCU aa4 ACU UGA 5-tRNA aa5

25. mRNA GCUACUUCG aa1 aa2 A peptide bonds 3-tRNA GAA aa3 4-tRNA GCU aa4 ACU UGA 5-tRNA aa5 Ribosomes move over one codon

26. mRNA ACAUGU aa1 aa2 U primarystructure of a protein aa3 200-tRNA aa4 UAG aa5 CU aa200 aa199 terminator or stop or stop codon codon Termination http://highered.mcgraw- hill.com/sites/0072437316/ student_view0/chapter15/a nimations.html#

27. Transcription & Translation http://highered.mcgraw- hill.com/sites/0072437316/student_view 0/chapter15/animations.html#