34_printout - 3/31/11 Jim Blankenship jeb14@cornell.edu...

Info iconThis preview shows page 1. Sign up to view the full content.

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

Unformatted text preview: 3/31/11 Jim Blankenship jeb14@cornell.edu 255-1983 219 Stimson Hall Office Hours: M,F 2:30 – 3:30 PM 219 Stimson Hall Note: Changed office hours for Friday 4/1 (1:30 – 2:30 PM) and Monday 4/4 (11:45AM – 12:45 PM). If you would like to meet me during this time period and neither of these times will work, please e-mail to schedule an appointment. Chris Fromme will hold office hours tomorrow Friday 4/1, 2:30 – 3:30,  457 Weill Hall. Please direct questions on the midterm (returned at end of class today) to Chris or Fo. Lecture 34 (3/31/11) DNA topology Reading assignment: pp. 954 ­62. Problems: N&C ch. 24, #11 (a,c, and d only) SG p. 306, #1 •In order, list the three steps in PCR that are repeated 25 ­30 Pmes to amplify a segment of DNA. • What Pme consuming and labor intensive step was included in the genome sequencing strategy that was eliminated in whole genome shotgun sequencing? 1 3/31/11 •In order, list the three steps in PCR that are repeated 25 ­30 Pmes to amplify a segment of DNA. • What Pme consuming and labor intensive step was included in the genome sequencing strategy that was eliminated in whole genome shotgun sequencing? 2 3/31/11 3 3/31/11 Comparative genomics of Mice and Men • The mouse genome is ~97.5 % identical to the human genome • Of ~30,000 genes, only about 300 genes are unique to either organism. 99% of mouse genes have homologues in humans! Man Mouse 4 3/31/11 What makes mice and men different? •  unique genes likely to confer traits unique to each of these organisms • related genes are similar (up to 70 ­90%) but not iden8cal. Related genes may have different structures and their protein products may have different ac8vi8es. Examples of human inherited diseases that result from a single nucleo8de change. • A gene can produce more than one protein product through alterna8ve splicing and posFransla8onal modifica8ons. •  Duplicated genes may evolve to acquire new func8ons unique to each organism. • A gene can produce more or less protein in different cells at various 8mes in response to developmental or environmental cues, and many proteins can express disparate func8ons in various biological contexts. More importantly, there is significant divergence in the noncoding sequences of mice and men! The linking number, a topological property of a circular DNA molecule, determines the degree of supercoiling. Duplex B form DNA contains 10.5 bp per turn of helix. When the two strands of a circular DNA duplex are wound around each other more or less than once every 10.5 bp, the duplex exists in a supercoiled state. 5 3/31/11 Topoisomers are different forms of a DNA molecule that differ only in their topological property such as linking number. Topoisomers of DNA can be interconverted by cuQng one or both strands. 6 3/31/11 7 3/31/11 Most cellular DNA is underwound 8 ...
View Full Document

This note was uploaded on 04/08/2011 for the course BIO BM 3350 taught by Professor Blakenship during the Spring '11 term at Cornell University (Engineering School).

Ask a homework question - tutors are online