Homework: read 12-3 and complete packet

1. Do Now:1. What structure makes proteins?2. Where are these found?3. Where is DNA stored? 4. Why not in cytoplasm? • Homework: read 12-3 and complete packet

2. DNA is safe inside the nucleus, but ribosome are in the cytoplasm!!

3. RNA is a “messenger molecule” that can take the code into the cytoplasm.

4. RNA and Protein Synthesis Trait

5. DNA vs. RNA

6. Overview of Protein Synthesis Transcription Translation

7. 1. RNA Ribonucleic acid Responsible for the movement of genetic information from the DNA in the nucleus to the site of protein synthesis in the cytosol

8. A. Structure of RNA: • Single-stranded Nucleic acid made up of repeating units, like DNA • Sugar molecule is RIBOSE (not deoxyribose) • Thymine is replaced with URACIL (U)

9. B. Forms of RNA • Messenger RNA (mRNA) a. STRUCTURE= RNA nucleotides in a single uncoiled chain b. FUNCTION= Carries genetic info from the nucleus to the ribosome

10. Transfer RNA (tRNA) a. STRUCTURE= RNA nucleotides in a single chain folded into a cloverleaf shape b. FUNCTION= binds to specific amino acids and helps form polypeptide chains

11. 3. Ribosomal RNA (rRNA) a. STRUCTURE = RNA nucleotides in a globular form b. FUNCTION = makes up the ribosomes where proteins are made

12. 2. Protein Synthesis • The production of proteins • The amount and kind of proteins produced in a cell determine the structure and function of the cell • Protein’s carry out the genetic instructions encoded in an organism’s DNA

13. Protein Structure • Proteins are POLYMERS • Made up of amino acids • There are 20 different amino acids that make up proteins

14. Hydro- phobic Hydro- philic Acid Base

15. a. Transcription *STEP 1 of PROTEIN SYNTHESIS*

16. T r a n s c r i p t i o n • What is it??? • making mRNA from DNA • NOTE: • Transcribe = to copy

17. T r a n s c r i p t i o n Steps • RNA polymerase binds to DNA at the promoter and separates the DNA strands. • RNA polymerase then uses one strand of DNA as a template. Using the template as a guide, nucleotides are assembled into a strand of mRNA.

18. Animation!

19. b. T r a n s l a t i o n *STEP 2 of PROTEIN SYNTHESIS*

20. T r a n s l a t i o n • The process TRANSLATING the message encoded in mRNA to assemble a protein. • Begins when mRNA leaves the nucleus through pores in the nuclear membrane • The mRNA then migrates to a ribosome in the cytosol, the site of protein synthesis Animation

21. THE GENETIC CODE • The genetic information necessary for making proteins is encoded in series of three mRNA nucleotides • Each combination of 3-mRNA nucleotides is called a CODON • Each codon codes for a specific amino acid

22. Codons in mRNA tRNA carries the “Anticodon” . . . Allows tRNA to match up with mRNA codon

23. **Start codon=AUG** If the mRNA sequence is A-A-U (codon) then the tRNA sequence is U-U-A (anticodon)

24. All three types of RNA are involved in Translation rRNA tRNA mRNA

25. Phase 1: Initiation • mRNA leaves nucleus • mRNA attaches to a ribosome • tRNA attaches to a start codon (AUG)

26. Phase 2: Elongation • tRNA anticodon binds with next mRNA codon • adjacent amino acids bond (begin a polypeptide chain) • Ribosomal unit shifts down to next codon, first tRNA leaves

27. Phase 3: Termination • Ribosomal unit stops when reaches stop codon • All units detach, and polypeptide folds into a protein

28. T r a n s l a t i o n Product = Amino acids linked to form proteins

29. Mutations • Mutations = errors • Mutations can occur as a “typo” in the sequence of nitrogen bases. • For example if a sequence should be A-C-G, a mutation could occur and it is now A-G-C . . . What affect could this have on the protein produced?

30. PROTEIN SYNTHESIS ANIMATION Complete together... Transcribe & Translate a Gene Activity