web_L34_08BIO311C - BIO 311C April 14, 2008 Exam 3 will be...

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BIO 311C April 14, 2008 Exam 3 will be held next Friday (April 18) in this room during the class period Exam 3 will cover lecture information and textbook reading assignments: - from “Energy Flow and the Importance of ATP (Mar. 5 syllabus topic) - through “Replication of DNA (April 7 syllabus topic) As in previous exams, nearly all Exam 3 questions can be answered by knowing the information presented in lectures and on the PowerPoint slides. The reading assignments also include information that answer most exam questions; a few questions may be taken directly from textbook reading assignments. The last 20 min. of Wednesday’s lecture period will be devoted to answering questions regarding the subject matter to be covered on Exam 3.
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The semiconservative mechanism of DNA replication maintains intact strands of DNA through successive generations of cells. DNA molecule in a cell DNA molecule in each of two cells resulting from the cell division of the cell at left DNA molecule in each of four cells resulting from cell divisions of the two cells at left * Modified from textbook Fig. 16.10b, p. 300
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The Central enzyme in DNA replication is DNA Polymerase. Three functional characteristics of DNA Polymerase are expressed at the same time: (1) it binds to the 3' end of a new growing polynucleotide chain, (2) it binds to the template polynucleotide chain, (3) it catalyzes the insertion (ligation) of a nucleotide into the growing polynucleotide chain. The ligated nucleotide is complimentary to the adjacent base on the template polynucleotide chain. DNA Polymerase From Textbook Fig. 16.16, p. 304 * Several different DNA polymerases occur in eukaryotic cells. The DNA polymerase that is central to the insertion of deoxyribonucleotides into the growing polypeptide chain is called pol III .
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DNA polymerase Reaction Catalyzed by DNA Polymerase (polynucleotide) n + dNTP (polynucleotide) n+1 + A second reaction coupled to this reaction is: + H 2 O pyrophosphatase 2 P i Textbook Fig. 16.13, p. 302 Note: this reaction extends the growing polynucleotide chain by one nucleotide in the 5' J 3' direction. * pyrophosphate
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pyrophosphatase DNA polymerase DNA polymerase Energetics of the Ligase Function of DNA Polymerase (polynucleotide) n + dNTP (polynucleotide) n+1 + + H 2 O pyrophosphatase 2 P i * 1. Δ - 15 kJ/mole 2. Δ - 30 kJ/mole Sum: (polynucleotide) n + dNTP (polynucleotide) n+1 + 2 P i + H 2 O Δ - 45 kJ/mole Thus, - 45 kJ/mole of energy is released for each nucleotide inserted into the growing polynucleotide chain, making the ligation reaction virtually irreversible.
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(1) DNA replication starts at a specific sequence of DNA, called the "origin of replication" site. The polynucleotide chains of the initial double helix are separated at that point. (2) DNA replication proceeds in both
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This note was uploaded on 09/28/2008 for the course BIO 311C taught by Professor Satasivian during the Spring '08 term at University of Texas at Austin.

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web_L34_08BIO311C - BIO 311C April 14, 2008 Exam 3 will be...

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