Biology 97 Lecture 11 Class Notes
Biology 97 Lecture 11 Class Notes 61860
Irvine Valley College
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This 2 page Class Notes was uploaded by Idda Colcol on Monday September 26, 2016. The Class Notes belongs to 61860 at Irvine Valley College taught by Amy McWhorter in Fall 2016. Since its upload, it has received 7 views. For similar materials see Genetics and Evolutionary Biology in Biology at Irvine Valley College.
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Date Created: 09/26/16
Bio 97 (#61860): Lecture 11 Class Notes 9/26/2016 (Powerpoint slides 28-47) I. Determining Gene Order for a Three Factor Cross A. two options for mapping 1. option 1 - map distance between genes 2. option 2 - order genes ﬁrst then map B. vg and b have the greatest distant apart 1. the greater distance are the genes on the outside C. no recombination is the most frequent event D. SCO = single cross over event E. for DCO (double cross over event), recombinant gene has to be in the middle F. for 3 genes, there is always 8 combinations 1. least frequent of those 8 classes (7 and 8) - shortcut way for determining recombinant genes for double cross over G. **exam** we might not always get 8 classes of progeny, there might be 6 1. there may be a class missing, so although 8 classes are possible, that doesn’t mean that 8 are always occurring 2. we describe what is present 3. there is a class missing, less frequent class is 0 with no double cross over 4. we get more accuracy with recombinations not with larger distances H. there is a problem with relying on greatest distance 1. it is less accurate 2. we get better accuracy from recombination frequencies turned into map units a) they are more accurate at shorter distances II. Interference A. 18.7 is more accurate than 17.7 B. interference 1. 3d connections between homologous chromosomes 2. the closer two positions are, the less likely a double cross over is to occur 3. the closer two regions are, the closer the interference value gets to 1 III.Calculating the level of interference A. map units also tell recombination frequencies 1. the chance that a recombination will occur in certain region 2. chance of double cross over a) product rule b) 12.3% x 6.4% (refers back to interference slide) 3. .64 is expected double cross over 4. .36 is interference value IV. Chromosomes and Genetic mapping A. linkage isn not going to be determined by recombination frequencies B. two genes can be linked if you can link middle gene, proving they are same chromosome V. More probability: Chi-square test A. statistical test B. for goodness of ﬁt 1. how well do results ﬁt C. is it truly close enough or is there enough variation from what we expect? VI. Why should we use chi-square test in genetics? A. correction on slide: should be 2.5% instead of 5% 1. 2.5% fall outside conﬁdence interval VII.Chi-square test for goodness of ﬁt A. we square it to make it positive B. classes we look at are usually phenotypic VIII.istribution of x^2 value A. 5.16 is between 2.366 and 6.251, that is 5%-10% B. p value 1. read out of how likely are those number variations of perfect due to chance alone C. df 1. categories of data sets or classes that you are summing up minus 1