Chapter 16 - The Molecular Basis of Inheritance Lectures 18, 19
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| 1020909419 | 1910: Thomas H. Morgan | - Genes are on chromosomes - Chromosomes: DNA+protein - Which is genetic material? |  | 1 |
| 1020909420 | 1928: Frederick Griffith | -Heritable factor can "transform" bacteria -What is the heritable factor? |  | 2 |
| 1020909421 | 1944: Oswald Avery, Colin MacLeod, and Maclyn McCarty | "Transforming" agent is DNA | | 3 |
| 1020909422 | 1952: Alfred Hershey and Martha Chase: | -DNA, not protein, is the genetic material of bacteriophages |  | 4 |
| 1020909423 | Nucleic acid: | -polymer of nucleotides -Nucleic Acids Are Assembled from Nucleotides | 5 | |
| 1020909424 | Nucleotides have 3 parts: | 1. Nitrogenous base 2. Sugar (5C) 3. Phosphate(s) |  | 6 |
| 1020909425 | Nitrogenous base | Pyrimidine: single 6C ring: -Thymine (T) -Cytosine (C) Purine: fused 5C-6C rings: -Adenine (A) -Guanine (G) |  | 7 |
| 1020909426 | Sugar (5C) | Deoxyribose: lacks 2'-OH |  | 8 |
| 1020909427 | Phosphate(s) | Attached to 5'-C | 9 | |
| 1020909428 | Polynucleotides | -phosphodiester Bonds Link Nucleotides -Sugar-phosphate "backbone" - Nitrogenous base "appendages" - Polarity (directionality) 5'-end = phosphate 3'end = hydroxyl (OH) |  | 10 |
| 1020909429 | Sugar-phosphate "backbone" | Repeating pattern |  | 11 |
| 1020909430 | Nitrogenous base "appendages" | Distinct sequence | | 12 |
| 1020909431 | Polarity (directionality) | 5'-end = phosphate 3'end = hydroxyl (OH) | 13 | |
| 1020909432 | 1952: Edwin Chargaff | DNA Base Composition Varies Between Organisms, but in Regular Ratios 1. Base composition varies between species 2. #A's = #T's, #G's = #C's |  | 14 |
| 1020909433 | Rosalind Franklin (Maurice Wilkins) | DNA Is a Double Helix of Anti-Parallel Strands -Double helix (2 strands) -Uniform diameter, base-spacing -Phosphates out, bases in |  | 15 |
| 1020909434 | Franklin's X ray diffraction of DNA |  | 16 | |
| 1020909435 | James Watson and Francis Crick | A=T, G≡C |  | 17 |
| 1020909436 | DNA Is a Double Helix of Anti-Parallel Strands | *Anti-parallel strands: -Stand W: 5'➞3' - Strand C: 3'➞5' *Sugar phosphate "backbones" *Bases "glue" strands together with H-bonds |  | 18 |
| 1020909437 | Bases "glue" strands together with H-bonds: | A=T, G≡C |  | 19 |
| 1020909438 | DNA Is a Double Helix of Anti-Parallel Strands | -Parent molecule -Strands separate -New strand synthesis |  | 20 |
| 1020909439 | Parent molecule: | Two complementary strands | 21 | |
| 1020909440 | Strands separate: | Each parent can serve as a template for a new complementary strand | 22 | |
| 1020909441 | New strand synthesis: | Nucleotides line up along the template according to base-pairing rules | 23 | |
| 1020909442 | Three Possible Models for DNA Replication | - Conservative - Semiconservative - Dispersive |  | 24 |
| 1020909443 | Conservative | Parents reassociate | 25 | |
| 1020909444 | DNA Is Replicated Semiconservatively | -Parents serve as templates -Produces hybrids: one parent, one new |  | 26 |
| 1020909445 | Matthew Meselson and Franklin Stahl (1958) |  | 27 | |
| 1020909446 | Dispersive | Each product strand is a mixture of parent and new | 28 | |
| 1020909447 | Origin of replication | - specific sites (sequences) where DNA replication starts - DNA Replication Proceeds Bidirectionally from Specific Sites - E. coli (and other bacteria) & Eukaryotes |  | 29 |
| 1020909448 | Origin of replication in an E. coli (and other bacteria) | 1 | | 30 |
| 1020909449 | Origin of replication in a Eukaryotes | many (faster for larger genomes) |  | 31 |
| 1020909450 | Several Proteins Help Prepare Template Strands for Replication | -Helicase -Single-stranded binding proteins -Topoisomerase -Primase | 32 | |
| 1020909451 | Helicase: | unwinds parental strands | 33 | |
| 1020909452 | Single-stranded binding proteins: | stabilize parental strands, prevent re-annealing | 34 | |
| 1020909453 | Topoisomerase: | relieves strain caused by strand unwinding | 35 | |
| 1020909454 | Primase: | synthesizes RNA primers to be extended | 36 | |
| 1020909455 | DNA polymerase | - Add nucleotides to existing chain - Can only add to the 3' end |  | 37 |
| 1020909456 | Requirement for DNA polymerase | -Existing strand (cannot initiate) -Template | 38 | |
| 1020909457 | DNA polymerase can only add to the 3' end: | Strands can only elongate in the 5'➞3' direction |  | 39 |
| 1020909458 | What are the consequences of DNA polymerase only being able to add to the 3' end of existing DNA strands? | Leading strand: continuous Lagging strand: discontinuous (in fragments) |  | 40 |
| 1020909459 | Leading strand | - Synthesized toward the replication fork - Continuous synthesis (DNA polymerase III) |  | 41 |
| 1020909460 | Lagging strand | - Synthesized away from the replication fork (DNA pol III) - Series of segments (Okazaki fragments) - DNA polymerase I - Ligase |  | 42 |
| 1020909461 | DNA polymerase I: | replaces RNA primers with DNA |  | 43 |
| 1020909462 | Ligase: | seals up gaps | 44 | |
| 1020909463 | Bacterial DNA Replication |  | 45 | |
| 1020909464 | Bacterial DNA Replication 2 |  | 46 | |
| 1020911700 | What happens at the end of eukaryotic chromosomes? Is it possible to synthesize all the way to the end of both strands? | Complete synthesis of linear DNA pieces is not possible with conventional replication machinery |  | 47 |
| 1020911701 | Telomeres: | -non-protein coding repetitive sequence found at the ends of chromosomes -Act as a buffer to protect protein coding genes -Shorten with each replication |  | 48 |
| 1020911702 | Telomerase | Telomerase Maintains Telomere Length In Germ Cells - protein-RNA complex - RNA-directed, DNA synthesis |  | 49 |
| 1020911703 | Various Mechanisms Repair DNA Damage |  | 50 | |
| 1020911704 | Various Mechanisms Repair DNA Damage |  | 51 |
