F13 lecture 8 v2

What are the genotypic and phenotypic ratios of the

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: 2 46 9 20 15 11 5 Homework 1 review Homework 1 review 3) The Drosophila melanogaster yellow gene is on the X chromosome. yellow/Y males and yellow/yellow females have yellow (lighter than normal) body color. yellow+/Y males, yellow+/yellow females, and yellow+/yellow+ females have wild type body color (i.e. yellow is recessive to yellow+; yellow+ is dominant to yellow). What are the genotypic and phenotypic ratios of the following two crosses. Be sure to state the ratios in each sex. a)  phenotypically yellow+ males crossed to phenotypically yellow females yellow+/Y males x yellow/yellow females -> males 100% yellow body color; 100% yellow/Y -> females 100% yellow+ body color; 100% yellow+/ yellow Homework 1 review b) phenotypically yellow males to yellow/yellow+ heterozygous females yellow/Y males x yellow/yellow+ females -> males 50% yellow body bolor, 50% yellow+ body color; 50% yellow+/Y; 50% yellow/Y -> females 50% yellow body bolor, 50% yellow+ body color; 50% yellow/yellow; 50% yellow/ yellow+ Homework 1 review Homework 1 review Homework 1 review b) What are the coefficient of coincidence and Interference measures in this three gene interval? observed frequency of double recombinants = (14+13)/2940 = 0.009 expected frequency of double recombinants = (rf between A and C)*(rf between C and B) = (0.084)*(0.126) = 0.011 coefficient of coincidence = observed freq of doubles/expected freq of doubles = 0.009/0.0011 = 0.82 interference = 1 - c of c = 1 – 0.82 = 0.18 (positive interference) changes in allele frequency •  can be caused by –  mutaGon –  migraGon (gene flow) –  selecGon –  geneGc driU mutaGons •  base subsGtuGons •  inserGon- deleGons (“indels”) –  may cause frame shiUs in protein coding regions –  transposible element inserGons •  chromosome rearrangements –  inversions –  translocaGons populaGon change by mutaGon alone is very slow mutaGon rates •  generally 1x10- 4 to 1x10- 5 per locus per generaGon •  vary across the genome –  hot spots and cold spots •  vary between species hIp://www.nature.com/scitable/content/19266/ pierce_table_17_3_FULL.jpg migraGon •  migraGon = movement of individuals between populaGons •  gene flow = movement of genes between populaGons •  migraGon can occur without gene flow –  if immigrants don’t succ...
View Full Document

This document was uploaded on 02/27/2014.

Ask a homework question - tutors are online