1. BIOLOGY 12 Protein Synthesis

2. Epigenetics our lifestyles and environment can change the way our genes are expressed do identical twins have the exact same DNA? Twins Video http://www.youtube.com/watch?v=avWwfuJYnnI

3. What do you know about RNA? single stranded. uracil instead of thymine 3 types – mRNA, rRNA, tRNA can go through nucleus into cytoplasm

4. What do you know about Proteins? polypeptides, long chains of amino acids amino group, carboxyl group, peptide bonds made in ribosomes used for structure – hair, muscles, nails, feathers, wool, hormones

5. Gene a sequence of nucleotides in DNA that provides the instructions to build a particular polypeptide note: one gene codes for one polypeptide

6. Codons sequence of three bases in DNA or mRNA that code for a particular amino acid triplet of nucleotides more than one codon can code for a single amino acid examples: CAA or GCU

7. Amino acidAbbreviation AlanineAla ArginineArg AsparagineAsn Aspartic acidAsp CysteineCys Glutamic acidGlu GlutamineGln GlycineGly HistidineHis IsoleucineIle LeucineLeu LysineLys MethionineMet PhenylalaninePhe ProlinePro SerineSer ThreonineThr TryptophanTrp TyrosineTyr ValineVal

8. Codons note: AUG is most often used as the start codon see table page 240

9. * remember: DNA never leaves the nucleus RNA is used as a messenger and a transporter

10. Three Types of RNA mRNA: messenger RNA delivers instructions to build a protein to the ribosome rRNA:ribosomal RNA structural component of a ribosome tRNA: transfer RNA transports appropriate amino acids to ribosome

11. Stage 1: Transcription DNA is used as a template to make a complementary mRNA mRNA transcribes the message from a gene and delivers it to the ribosome DNA  mRNA

12. Stage 1: Transcription Initiation DNA uncoils at the site of a gene one strand will act as a template

13. Stage 1: Transcription Elongation RNA polymerase attaches to the DNA RNA nucleotides match up to the DNA template forming mRNA base pair rules: A-U and C-G

14. Stage 1: Transcription Termination mRNA is released

15. Stage 1: Transcription Posttranscriptional Modification 5’ cap added to start of mRNA, for protection from digestion poly-A tail is a string of adenine bases at the end of mRNA then mRNA leaves nucleus through nuclear pores

16. Stage 1: Transcription

18. Stage 2: Translation a ribosome assembles amino acids in a specific sequence mRNA is transcribed into a polypeptide mRNA  protein

19. Stage 2: Translation two subunits of a ribosome bind to the mRNA the ribosome moves along the mRNA in the 5’ to 3’ direction, three nucleotides at a time this is the reading frame

20. Stage 2: Translation the ribosome recognizes the start codon (AUG) new amino acids are added each time the ribosome reads a new codon

21. Stage 2: Translation tRNA delivers the amino acids it’s anti-codon recognizes the codons in the mRNA each tRNA arrives at the A site (acceptor) the next tRNA arrives at the A site and the tRNA prior to that shifts to the P site (peptide) this is where peptide bonds are formed between adjoining amino acids

23. Stage 2: Translation the ribosome then shifts (translocates) to the next codon the process will continue until the ribosome reaches a stop codon

24. Stage 2: Translation A site P site

26. Protein Synthesis

27. Wisc-Online Animation http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap1302

28. Protein Synthesis Example what makes a firefly glow? Learn Genetics http://learn.genetics.utah.edu/content/begin/dna/firefly/fireflymon8.swf

29. Protein Synthesis Transcribe and Translate http://learn.genetics.utah.edu/content/begin/dna/transcribe/

30. Textbook Review protein synthesis Read: pages 237-244 pages 250-253 Questions:page 241 # 1, 4, 5, 6, 9, 10, 11 page 254 # 3, 9