Ch 16 DNA (Molecular basis of inheritance)

1. Ch 16 DNA(Molecular basis of inheritance)

2. DNA STRUCTURE DNA LANGUAGE OF LIFE

4. DNA Deoxyribonucleic acid Sugar in DNA is Deoxyribose Nucleic is in the Nucleus Acid comes from the acidic phosphate ions Chromosomes are made of DNA

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6. What are the DNA instructions for? DNA tells cell when and how to make proteins. DNA has code for physical traits

7. DNA has its own language, and with it, it writes the story of life. How many letters in: English Alphabet Hawaiian Alphabet DNA alphabet? 26 13 Only 4 letters! T A C G-CAT G

8. Imagine you had all of the pieces to a puzzle but you didn’t know how they fit together. Scientists had the pieces of DNA. Fame and fortune would go to the one who solved this puzzle...

9. The Race to Establish the Structure of DNA THE PLAYERS THE PIECES adenine guanine cytosine thymine deoxyribose phosphate

10. Examine the data below. Do you notice a pattern?

11. So did Erwin Chargaff... all species had similar ratios of A, T, G, C Chargaff’s Rule Amount of A, T, G, C varies by species, but…. discovered that DNA contains equal amounts of Adenine & Thymine and equal amounts of cytosine and guanine The basis of these rules remained unexplained until discovery of double helix

12. Could it be that these pieces of the puzzle fit together….. But what about deoxyribose and phosphates, where do those pieces fit? G C T A C G C G T A

13. ROSALIND FRANKLIN & WILKENS Took pictures of DNA using X-RAY DIFFRACTION

14. DNA X- Ray Crystallography What is the distance? 2 nm distance These image is provided clues to the shape of the DNA molecule.

15. Enter……...WATSON & CRICK

16. Who discovered the structure of DNA? Rosalind Franklin took x-ray photographs of DNA, DNA is a double helix. Sugar-phosphate is the backbone This picture helped James Watson and Francis Crick constructed the model and the structure of DNA.

17. FIRST TO DISCOVER THE STRUCTURE OF DNA In 1953, James Watson and Francis Crick discovered the structure of DNA Proposed that DNA is shaped in a double helix (like a zipper that is twisted)

18. Why Does a Purine Always Bind with A Pyrimidine?  Distance is 2 nm  Evidence X- Ray photo of DNA

19. What does DNA look like??

21. Double Helix- • Double helix- 2 coils • 2 polymers of nucleotides • Link in the middle at bases • Then right handed twist

22. DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G, or C) “Legs of ladder” Phosphate and sugar backbone • The ladder is held together by Hydrogen Bondsin the middle works like a zipper. • Covalent Bonds on the uprights (legs of ladder). Double stranded

23. P P D--A---T--D P P D--C---G--D P P D--T---A--D P P D--G---C--D P P Untwisted view P: phosphate group D: deoxyribose A: adenine T: thymine C: cytosine G: guanine

25. Anti-Parallel •refers to the 2 connected strands in double helix = one strand is upside down! Antiparallel: one strand (5’ 3’), other strand runs in opposite, upside-down direction (3’  5’) 5’ end of DNA = phosphate is at end. DNA is directional Middle – Nitrogen bases 3’ end of DNA = sugar w/ hydroxyl group (OH) is at the end 5’ and 3’ refer to the carbon # on the sugar

27. 5’ and 3’ ENDS Each Side is ANTIPARALLEL

28. WHAT ARE THE FOUR POSSIBLE NITROGEN BASES? Classifications: Purines: two rings of carbon and nitrogen Pyrimidines: one ring of carbon and nitrogen Thus…..four possible nucleotides. ADENINE (A) GUANINE (G) CYTOSINE (C) THYMINE (T)

30. Grammar Rules ONLY ONE! Bases Some bases are like BFFs G C A T Guanine Cytosine Adenine Thymine G – C A - T A G C C A T G T C G G T A C

31. Complimentary Base Pairing • Base Pairs rules: • Adenine bonds Thymine • (two hydrogen bonds) • Guanine bonds Cytosine • (three hydrogen bonds) • Purine pairs with pyrimidine • NOT identical. • A ≠ A • G ≠ G etc

32. Each DNA strands are compliments of the other A C G T A T G C A T Original strand Matching Copy

33. T C G A A C G T T G G C A T Original Strand 5’-End 3’ – end A G C T T G C A A C C G T A Use the complimentary bases to make the complementary strand to this original strand of DNA 3’-End 5’ – end

35. Structure of DNA DNA is made of small molecules (monomers) Nucleotides P SUGAR SUGAR NITROGENBASE NITROGENBASE • Sugar • Phosphate • *Nitrogen Base P * * Most important! – Determines what kind of nucleotide

36. Polymer: A Polynucleotide • MANY nucleotides (“links”) bonded together Nucleotide Structure DNA has an overall negative charge b/c of the PO4-3 (phosphate group)

37. Nucleoside Structure

38. Minor Groove Major Groove

39. What is the function of DNA? Make proteins Blueprint for life: contains genetic information to make a new organism Controls cellular processes Contained in all living cells (eukaryotic and prokaryotic)

40. Importance of DNA • The sequence of nucleotides forms the unique genetic information of an organism. • A stretch of DNA just 10 nucleotides long can have more than 1 million possible sequences of the four bases.

41. 5. (3’ end) 5. (5’ end) 3. (2 bonds) 6. T 1. 2. 6. A • Label the DNA strands shown below. • Label a deoxyribose sugar molecules • a phosphate molecules (PO43-) • Hydrogen bonds • Label the phosphodiester bonds • The 5’ and 3’ ends • Label the bases that are not already labeled • Purines • Pyrimidines 3. (3 bonds) 6. C 4. 6. G A and G C and T 5. (5’ end) 5. (3’ end)

42. THE CENTRAL DOGMA Replication Protein DNA RNA Transcription Translation

43. DNA Comparison Double-stranded Circular One chromosome In cytoplasm No histones Supercoiled DNA Double-stranded Linear Usually 1+ chromosomes In nucleus DNA wrapped around histones (proteins) Forms chromatin Prokaryotic DNA Eukaryotic DNA

45. QUESTION: Where is genetic information stored? a) in the ribosomes of cells b) within the proteins of cells c) within the DNA of cells d) within the membrane of cells The answer is here somewhere! *It is important to remember that scientists didn’t always have the answers, experiments and research must be performed and consensus reached. Science is a process!

46. Finding the molecule of heredity The material must be… Able to store informationthat pertains to the development, structure and metabolic activities of the cell Stable so that it can be replicated Able to undergo changes (mutations)

47. 1869 – Discovering Nucleic Acids Swiss Physician, Johannes Friedrich Miescher isolated the chemical he called “nuclein” from the nuclei of white blood cells Now called nucleic acids (macromolecule) DNA (deoxyribonucleic acid) RNA (ribonucleic acid) Miescher used pus and bloodstained bandages from a hospital to study “nuclein”

48. NUCLEIC ACIDS- • Function: make proteins • Nucleotides -monomers of nucleic acid and found in nuclein 2 Types: • RNA-ribonucleic acid • DNA-deoxyribonucleic acid

49. NUCLEOTIDES • 3 parts: • 5 carbon sugar (either ribose or deoxyribose), • nitrogen-containing base • phosphate group.

50. 5 CARBON RING SUGAR RNA DNA