Understanding DNA Replication and Gene Expression: Key Concepts and Quizzes
This resource covers essential topics in DNA replication and gene expression, focusing on the central dogma, major players, and the genetic code. It highlights the Meselson-Stahl experiment, which confirms the semiconservative model of DNA replication. Additionally, the material includes relevant quizzes to assess comprehension of Chapters 14 and 15. Key enzymatic processes, such as the roles of DNA polymerase, helicase, primase, and ligase in replication, are detailed. Engage with interactive quizzes at www.mhhe.com/raven7 for a deeper understanding.
Understanding DNA Replication and Gene Expression: Key Concepts and Quizzes
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Presentation Transcript
Bio 178 Lecture 28 DNA and Gene Expression
Reading • Chapters 14 & 15 ? Quiz Material • Questions on P 300 & 318 • Chapters 14 & 15 Quizzes on Text Website (www.mhhe.com/raven7)
DNA • DNA Replication • Gene Expression • Central Dogma • Major Players • Genetic Code • Transcription Outline
Hershey and Chase Experiment McGraw- Hill Video
How Does DNA Replicate? Complementarity suggested a copying mechanism. Eg. 5´-ACGTAAT-3´ pairs with 3´-TGCATTA-5´ There were 3 hypotheses: Conservative, dispersive, & semiconservative. • Meselson and Stahl (1958) The semiconservative hypothesis is correct. Read P 288-289 & predict what results would have been obtained for the other hypotheses (hand this in also).
Meselson And Stahl Experiment McGraw-Hill Video
The Replication Process (E. coli) • DNA Polymerases Enzymes that synthesize DNA: (a) Require a primer. (b) Can only synthesize in the 5´ to 3´ direction (copy a template that is 3´ to 5´). (c) Have nuclease activity, including 3´ to 5´ exonuclease activity (proofreading). • Leading and Lagging Strands Leading strand - synthesized continuously (5´ to 3´). Lagging strand - synthesized discontinuously (5´ to 3´ stretches (Okazaki fragments) as the DNA opens up, with filling in afterwards).
The Replication Process (Cntd.) DNA Pol III is the main polymerase. • Some of the “Other” Enzymatic Activities 1. DNA Helicase Opens the DNA in front of polymerase. 2. DNA Primase Synthesizes primers (RNA). 3. DNA pol I Removes the primers (*5 ´ to 3´ exonuclease) and replaces them with DNA. 4. DNA Ligase Ligates Okazaki fragments (phosphodiester bond).
