1. DNA Transcription and Translation Review

2. There are 3 types of RNA: Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA)

3. All RNA is … Single stranded Many different shapes “Cheap copy” of DNA

4. Transcription First step in making proteins Process of taking one gene (DNA) and converting into a mRNA strand DNA -> RNA Location: Nucleus of the cell

6. Steps to Transcription 1. An enzyme attaches to the promoter (start signal region) of a gene and unwinds the DNA

7. Steps to Transcription (Cont.) 2. One strand acts as a template.

8. Steps to Transcription (Cont.) 3. A mRNA copy is made from the DNA template strand by RNA polymerase 4. A mRNA copy is made until it reaches the termination (stop signal) sequence 5. The two strands of DNA rejoin.

9. Template vs. Non Template Strand

10. Transcribe this DNA to mRNA

11. Think… 1. Where in the cell does transcription occur? 2. What nucleic acids are involved in the process of transcription? 3. What is the importance of transcription? 4. In transcription, how come the whole DNA molecule is not copied into mRNA? 5. How does one gene differ structurally from another? 6. Because one gene differs from another, what molecules in the cell will also be different?

12. Label the Transcription diagram

14. Pg. 339

15. PROTEINS!

16. Proteins are made up of amino acids!!! Proteins are polymers of amino acids Only 20 different amino acids BUT there are hundreds of thousands of different proteins How can this be?

17. Let’s compare to it to the English language How many letters are in the alphabet? A,b,c,d,… 26 How many words are there? Almost infinite! Each word has a unique structure of letters. Similar to proteins and amino acids

18. Do Now How does this mRNA sequence leave the nucleus? Where does it go?

19. How do amino acids form these peptide chains? Peptide Bonds – Link each amino acids together to form proteins

20. Protein Structure http://www3.interscience.wiley.com:8100/legacy/college/boyer/0471661791/structure/HbMb/hbmb.htm

21. Translation Production of proteins from mRNA mRNA goes to the ribosomes in the cytoplasm or the RER and produces proteins

23. Steps to Translation 1. mRNA leaves the nucleus and binds to a ribosome 2. the 5’ end of mRNA binds to ribosome

24. Ribosome Two subunits to the ribosome 3 grooves on the ribosome (A, P, E) A: tRNA binding site P: polypeptite bonding site E: exit site

25. Steps to Translation (Cont.) 3. Ribosome looks for the start Codon (AUG) Codon: group of 3 nucleotides on the messenger RNA that specifies one amino acid (64 different codons)

27. Steps to Translation (Cont.) 4. Amino acids attached to a tRNA molecule and are brought over to the mRNA. 5. This tRNA has an anticodon that matches the codon on the mRNA strand Anticodon: Group of 3 unpaired nucleotides on a tRNA strand. (binds to mRNA codon)

28. tRNA

29. Steps to Translation (Cont.) 6. tRNA binds to the mRNA sequence and adds an amino acid 7. Each amino acid matches up with 1-6 tRNA molecules 8. tRNA leaves and amino acids bond together through a polypeptide bond

30. Steps to Translation (Cont.) 9. The mRNA sequence continues until a stop codon is reached. 10. The amino acids disconnect from the mRNA sequence and a protein is formed.

31. Transcription Translation mRNA Nucleus Cytoplasm Proteins Amino Acid

32. Peptide Chains b/c of codons Peptide Bond Dehydration Synthesis

33. DNA mRNA Anti- codon tRNA Amino Acid Codon Peptide Chain or protein rRNA

34. What else… Video to help you… http://youtu.be/h3b9ArupXZg What do you think would happen if there was a mistake in transcription?