This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: BIS101001 Lecture 6. 1/26/09 Bacterial genetics and mapping Announcements Pick up review quiz after Wednesday in boxes outside MCB ofFce. Midterm 1 is this Wednesday 1/28 in class. 100 points, covers material from lectures 15 Show your work! No calculators Must be in pen for regrade request Practice midterms on course website (“Resources” section) LECTURE 6: OUTLINE Statistical signifcance oF linkage UseFulness oF bacterial genetics Experimental methods Gene transFer in bacteria: 1) Conjugation: bacterial sex Bacterial gene mapping by conjugation Bacterial gene mapping by recombination 2) TransFormation (DNA uptake) 3) Transduction (bacteriophages) Chisquare analysis Is there statistical evidence for linkage? For Ab / aB x ab / ab testcross, Ab /ab 280 aB /ab 270 AB /ab 220 ab /ab 230 Calculated map distance = 220 + 230 / 1000 = 45cM Two possibilities 1) Linked genes 45cM apart 2) Random deviation from expected 1:1:1:1 ratio Chisquare analysis For Ab / aB x ab / ab testcross, Ab /ab 280 aB /ab 270 AB /ab 220 ab /ab 230 Null hypothesis = simplest and most straightforward explanation. In this case, assume genes are unlinked and random ¡uctuation caused observed progeny Chisquare analysis Chisquared formula: Chisquared = total of (observed  expected) 2 observed for all classes Chisquared = (280250 ) 2 + (270250 ) 2 + (220250 ) 2 + (230250 ) 2 250 250 250 250 3.6 + 1.6 + 3.6 + 1.6 = 10.4 Consult a chisquared table Degrees of freedom (df) = # classes  1 In our case, 4 gamete types  1 = 3 degrees of freedom Consult a chisquared table...
View
Full Document
 Spring '09
 Sanders
 Genetics, Bacteria, Escherichia coli, Bacterial conjugation

Click to edit the document details