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Lab Biology- Chapter 10 Honors Biology- Chapter 9
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Found on chromosomes Segment of DNA Codes for a trait
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Characteristic due to a single gene or multiple genes Eye color Hair color Blood type
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Deoxyribose sugar Phosphate group Nitrogen containing base ◦ Four possible bases
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2 rings of carbon and nitrogen Adenine Guanine
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1 ring of carbon and nitrogen atoms Thymine Cytosine
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DNA is composed of 2 nucleotide chains Nucleotides connected through covalent bonds
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Each strand has a 5’ and a 3’ end Each strand runs in an opposite (antiparallel) direction
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Nucleotide linkage Covalent bonds between sugar and phosphate molecules Forms a sugar- phosphate backbone 5’ 3’
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Covalent bond Chemical bonding through sharing of electron pairs
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Purine Pyrimidine A T – 2 Hydrogen bonds C G – 3 Hydrogen bonds
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Hydrogen bonding between base pairs Hydrogen atom - electronegative atom
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Hydrogen bonds? Covalent bonds?
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Chargaff’s rule The DNA of any given species contains ◦ adenine = thymine ◦ guanine = cytosine
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Wilkins and Franklin Used X-ray diffraction ◦ A picture of how X-rays bounced off a DNA molecule FranklinWilkinsX-ray diffraction
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X-Ray diffraction Used to determine arrangement of atoms within a crystal structure Distance between dark spots- distance between turns of the helix
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Performed no physical experiments on DNA Spent a lot of time thinking about DNA Focused on creating a model that fit with the data
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Wilkins, Watson, and Crick received the Nobel Prize in 1962 Franklin died in 1958 and was not recognized Nobel Prize cannot be awarded posthumously
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Write a two paragraph reflection on Rosalind Franklin. ◦ One paragraph should detail her contribution to the discovery of the structure of DNA. ◦ Second paragraph should state your answer to the questions: Do you think Franklin deserved the Nobel Prize? Why do you think she did not receive more recognition? ◦ Evidence must be provided to support your opinions. ◦ Complete this assignment on loose leaf paper.
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Occurs in all living organism Takes place in the nucleus One double stranded molecule two identical copies Original strand New strand
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Helicase (enzyme) holds the two strands apart ◦ Break hydrogen bonds between bases
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Replicates simultaneously
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DNA polymerase synthesizes DNA by adding nucleotides in a 5’ 3’ direction Leading strand- continuous ◦ Moves in the direction of unwinding Lagging strand- discontinuous
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Lagging Strand Discontinuous Forms in the opposite direction of replication fork Creates Okazaki fragments Must wait for a new primer to be placed
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DNA Primase- lays down short segments of RNA primer DNA Polymerase III- adds new nucleotides DNA ligase- bonds Okazaki fragments together
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Semiconservative model
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What happens when DNA Polymerase makes a mistake? Mutation- Change in nucleotide sequence Can be repaired through DNA repair mechanisms
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One nucleotide is substituted for another Sickle Cell Anemia
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A nucleotide is deleted Cystic fibrosis ◦ Deletion of "AT" from the sequence "ATAT" in the CFTR gene Causes a frameshift
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A nucleotide is added Huntington’s disease Causes a frameshift
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DNA segment is broken and flipped No frameshift No loss of genetic information Different order Hemophilia
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Part of the gene is moved ◦ Either moved on the same chromosome or moved to a different chromosome A form of Down syndrome Part of Chromosome 21 is moved to Chromosome 14
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DNA Replication Game http://www.nobelprize.org/educational/medi cine/dna_double_helix/dnahelix.html http://www.nobelprize.org/educational/medi cine/dna_double_helix/dnahelix.html Honors: DNA Replication http://www.wiley.com/college/pratt/047139 3878/student/animations/dna_replication/in dex.html http://www.wiley.com/college/pratt/047139 3878/student/animations/dna_replication/in dex.html DNA Replication: http://www.mcb.harvard.edu/losick/images/t rombonefinald.swf http://www.mcb.harvard.edu/losick/images/t rombonefinald.swf
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