LESSON 10.1 DNA Deoxyribonucleic Acid

1. LESSON 10.1DNADeoxyribonucleicAcid

2. nucleus A. Found in the ________________ of the cell B. Control _____________ synthesis and thus control cell activities C. Has shape of a ____________________ D. Building block is a _______________ Sequence of nucleotides determines what DNA will do. protein double helix nucleotide

4. Nucleotide 1) phosphate group – PO4 2) 5-C sugar = deoxyribose

5. Find the missing oxygen! RNA DNA

6. 3) a nitrogen base (one of the four) a) purines = double ring structure adenine (A) “Another Guido guanine (G) Pumps” b) pyrimidines – single ring structure thymine (T) “Tut & Cleopatra cytosine (C) live in Pyramids”

7. Complementary base pairing • PURINES ALWAYS PAIR W/ PYRIMIDINES

8. Double bond Triple bond

9. DNA STRUCTURE HISTORY

10. Thomas Hunt Morgan showed role of chromosomes genetic information.

11. Oswald Avery showed thatgenes were not only real, but that they were composed of DNA

12. Props to Linus Pauling • He thought DNA was a triple helix !

13. Evidence for DNA Structure: 1) 1951 – Chargaff figured out that # of A always equaled # of T ! # of G always equaled # of C ! A=T and G C This is known as CHARGAFF’S RULE (base-pairing rule)

14. Do you think our DNA is mostly A-T’s or C-G’s?

15. 1952 – Alfred Hershey and Martha Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not.

16. * Sulfur bonds with protein, P bonds with DNA

17. 2) 1952 Rosalind Franklin used x-ray diffraction to observe the structure of DNA. A powerful x-ray beam was aimed at the sample and the scattering pattern was recorded on film. She worked with Maurice Wilkins.

18. 3) A few weeks later Watson and Crick examined Franklin’s work and in 1953 they had determined the structure of DNA by building a model. In 1962, Watson, Crick and Wilkins shared the Nobel prize for their discovery. Franklin had diedin 1958 and did not share the prize.

19. WATSON AND CRICK WATSON Died 2004 87 yrs old (2015)

21. In 1962, Watson, Crick and Wilkins shared the Nobel prize for their discovery. Franklin had died in 1958 and did not share the prize.

22. Covalent Share e- Ionic Give or take e- Hydrogen Weak H+ and anything (-) Peptide Holds proteins (C-N-C) Polar Covalent Holds H2O together Uneven sharing Glycosidic Holds sugar (C-O-C) What are the 6 bonds we learned?

23. sugars and phosphates C. The Watson-Crick Model of DNA 1. Double Helix = like a twisted ladder a) backbone = __________________ rungs = _____________________ (always a purine to a pyrimidine, A-T or C-G) b) 2 sides held together by weak __________________ bonds c) backbone held together by __________________ bonds nitrogen bases hydrogen covalent (phosphodiester)

24. 5’ 3’ 3’ 5’

25. backbone bases "rungs" P N base D N base P N base D N base covalent hydrogen bonds P N base D N base P D N base N base

26. How many nucleotides make up 360 degree turn? 10

28. Why is DNA slightly NEGATIVELY charged?

29. Human Genome Project • Project completed in 2003 where scientists sequenced 25,000 genes and FOUND where they are on EACH of the 46 CHROMOSOMES!

30. Why would we want to know where our genes are and what they do?

31. Why does it make sense to hold the 2 strands of DNA together by weak H bonds? • Bc 2 strands need to break easily to duplicate DNA

32. DNA REPLICATION When does replication occur in the cell cycle? S stage of interphase

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35. DNA REPLICATION BEGINS AT MANY SITES ALONG A GIANT DNA MOLECULES

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38. 3) New complimentary bases from the cell’s nucleoplasm are added to the unraveled DNA strands by DNA POLYMERASE, and new H bonds are made between the bases. “ZIPS UP”

39. Bonds form between the phosphates and sugars of the new backbone. 5) 2 DUPLICATED DNA strands are made! Each with an old and a new strand

40. Replication starts at several pointsalong the helix, thus allowing replication to take place at a much quicker rate. • If replication did not start at several points at one time, the replication process of the chromosomes of a fruit fly would take 16 dayS! • It actually takes approximately 3 minutes (6000 sites copied simultaneously). • The cells lining the stomach divide rapidly and can replicate their DNA every 20 minutes. • Bases are added at a rate of 50 – 100 bases per second. (500/sec in bacteria)

41. The cell has a built in “proofreading” function performed by enzymes or proteins. • The degree of accuracy is about one error per billion nucleotides.

42. A group of more than 20 repair enzymes recognize and remove damaged nucleotides and replace them with new ones.

44. Which one is DNA replication?

45. 10.2 RNA a) Same as DNA except: it is _________-stranded b) _________ replaced thymine (still bonds with ___________) single Uracil adenine

46. ribose c) sugar = _____________ (one more oxygen atom than deoxyribose)

47. (bonds)

48. A. 3 Types of RNA messenger • mRNA – _____________ RNA – copies DNA (gets transcript) to leave nucleus - has a CODON to code for an amino acid (3 nucleotides)

49. Where is the mRNA? DNA RNA Polymerase mRNA Complementary mRNA transcript

50. Adding Nucleotides 5’ 3’ growing RNA transcript 5’ 3’ direction of transcription Addition of nucleotides in the 5’ to 3’ direction of the DNA