11.1 Genes are made of DNA

1. 11.1 Genes are made of DNA

2. Griffith Experiment

3. Viral DNA Background • Virus – a package of nucleic DNA wrapped in a protein shell that must use a host cell to reproduce, they are not considered living organisms • Bacteriophage – virus that infects bacteria • There must be something in a virus that allows it to transform bacteria

4. Hershey Chase Experiment

5. Question 1 & 2 • Explain how experiments done by Griffith, Avery & Hershey and Chase supported that genes are made of DNA? [4 points] 2. Identify the parts of DNA and how the double helix is put together (bases)? [4 points]

6. 11.2 Nucleic acids store information in their sequences of chemical units

7. DNA Nucleotide

8. Nucleotides • Nucleotides are individual units of DNA that compose the whole chain • Each nucleotide consists of: a phosphate a suger (Deoxyribose) One of four nitrogen base (A,T,C,G)

9. Nitrogenous Bases

10. DNA- structures

11. Rosalind Franklin & Maurice Wilkins 1950’s photographs of the DNA molecule using X-ray crystallography which showed the shape to be a helix

12. Erwin Chargaff • 1951, proved that the % of A = T and % of G = C

13. Watson &Crick • 1953, used data from the other scientists and built models to finally figure out the exact structure of DNA • 1962 won the nobel prize in Medicine

14. 11.3 DNA replication is the molecular mechanism of inheritance

15. DNA Replication • Enzymes are protein molecules that catalyze chemical reactions in a cell – usually any protein ending in “ase” is an enzyme • Helicase- unwinds DNA • DNA Polymerase 3- Adds complementary nucleotide • DNA Polymerase 1- Checks for error

16. DNA Replication

17. 11.4 A gene provides the information for making a specific protein

18. Beadle and Tatum • Beadle and Tatum discovered when looking at mutant Neurospora crassa (bread mold) • Individual gene produces a specific enzyme • One gene - one polypeptide (combinaiton of amino acids)

19. Deoxyribose sugar A,T,C,G Double strand Nucleus Ribose sugar A,U,C,G Uracil pairs with adenine Single strand Nucleus to cytoplasm DNA & RNA

20. DNA to Protein

21. Table of Codons

22. 11.5 There are two main steps from genes to proteins

23. Transcription: Base Pairing of mRNA with DNA

24. Steps of Transcription 1. DNA double helix unwound and separated by RNA polymerase 2. RNA polymerase adds RNA nucleotides together, making a single strand of mRNA which is complementary to 1 strand of the DNA

25. Steps of Transcription 3. mRNA is processed (modified) before leaving the nucleus • introns (non coding regions) are cut out of the mRNA • exons (coding regions) are “spliced” together to form the final mRNA product 4. Introns are cut out and exons are spliced together to form the final copy of messenger RNA (mRNA)

26. RNA editing

27. Transfer RNA (tRNA)

28. Adding Amino Acids to a Polypeptide Chain

29. Steps of Translation 1. mRNA leaves the nucleus and is transported to the ribosome where translation takes place 2. Ribosome holds onto the mRNA, the mRNA codon AUG is located in the P site of the ribosome 3. tRNA carries an amino acid to the P site of the ribosome 4. Another tRNA carries the next amino acid to the A site of the ribosome

30. Steps of Translation 5. Two amino acids are joined together with a peptide bond 6. tRNA in the P site leaves 7. Ribosome moves along the mRNA until the next codon is located in the A site (the tRNA which was located in the A site is now in the P site and is holding the peptide chain) 8. tRNA carries the next amino acid to the A site

31. Steps of Translation 9. New amino acid is joined to the peptide chain (the polypeptide is made of 3 amino acids) • tRNA in the P site leaves 11. Process continues until a stop codon appears in the A site of the ribosome 12. Polypeptide is now complete

32. Rules for translation 1. Codon is a three-base “word” that codes for one amino acid 2. Determine the amino acid coded for by an mRNA codon use the genetic code 3. Genetic code is universal – all species use the same genetic code, the same 20 amino acids are used in all living organisms

33. Summary of Translation Process

34. 11.6 Mutations can change the meaning of genes

35. Point vs. Frameshift Mutations

36. Chromosome Mutations

37. How mutations affect genes 1. A mutation is any change in the nucleotide sequence of DNA. 2.Two categories of mutations a. Base substitutions (point)– replacement of one nucleotide with another i. This can change the protein or not change the protein b. Base insertions or base deletions (frameshift) – addition of an extra nucleotide or subtracting a nucleotide i. Have more effect on the protein than a substitution

38. What causes mutations? 1. Mistakes during DNA replication can cause mutations 2. Mutagens – physical or chemical agents that cause mutations a. Physical mutagens – high energy radiation, X-rays, Ultraviolet light b. Chemical mutagens – chemicals that are similar to DNA bases and cause incorrect base-pairing

39. Body Cells Cancers Gametes Birth defects Genetic disorders Mutations Effects

40. Ch. 11 Test • Vocabulary • DNA & RNA structure • Replication, transcription, translation- content and problems • Scientists & experiments involved • Mutations & mutagens- types and effects

41. 13.1 Biologists have learned to manipulate DNA

42. 13.2 Biologists can engineer bacteria to make useful products

43. Plasmids

44. Restriction Enzymes

45. Gene Cloning

46. Genomic Library

47. Nucleic Acid Probe

48. 13.3 Biologists can genetically engineer plants and animals

49. Transgenic Plants

50. 13.4 DNA technologies have many applications