{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

LECTURE 3-DNA polymerases-poor enzymes doing half the job

LECTURE 3-DNA polymerases-poor enzymes doing half the job -...

Info icon This preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
1. DNA replication is semi-conservative. 2. DNA polymerase enzymes are specialized for different functions. 3. DNA pol I has 3 activities: polymerase, 3’-->5’ exonuclease & 5’-->3’ exonuclease. 4. DNA polymerase structures are conserved. 1. But: Pol can’t start and only synthesizes DNA 5’-->3’! 1. Editing (proofreading) by 3’-->5’ exo reduces errors. 2. High fidelity is due to the race between addition and editing. 3. Mismatches disfavor addition by DNA pol I at 5 successive positions. The error rate is ~ 1/10 9 . DNA polymerase Summary
Image of page 2
DNA replication is semi-conservative Meselson-Stahl experiment 1. Grow E. coli on 15 N (“heavy”) ammonia 2. Switch to 14 N (normal, “light”) ammonia 3. Harvest aliquots as a function of time 4. I solate DNA 5. Separate on the basis of DNA density using density gradient centrifugation 2
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Predictions of Meselson-Stahl experiment Conservative Semi-conservative Distributive 0 1 2 Parental strands stay together -- HH maintained Parental strands separate every generation -- no HH after 1 generation Parental strands broken -- no LL in generation 2
Image of page 4
Results of Meselson-Stahl experiment Conservative Semi-conservative Distributive 0 1 2 Parental strands stay together -- HH maintained Parental strands separate every generation -- no HH after 1 generation Parental strands broken -- no LL in generation 2 Results Graph Picture
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Conservative Semi-conservative Distributive 0 1 2 Parental strands stay together -- HH maintained Parental strands separate every generation -- no HH after 1 generation Parental strands broken -- no LL in generation 2 Results Graph Picture DNA replication is semi-conservative
Image of page 6
Arthur Kornberg discovered DNA dependent
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern