1. Linkage Questions Chapter 6

2. Questions 1 Genetic recombination occurs during crossing over in Meiosis I. When two homologous chromosomes form chiasma genes from a paternal chromosome ay cross over to the maternal chromosome Genetic recombination occurs during crossing over in Meiosis I. When two homologous chromosomes form chiasma genes from a paternal chromosome ay cross over to the maternal chromosome This involves physical breaking and recombination of two chromosomes This involves physical breaking and recombination of two chromosomes Recombination leads to new combinations of genes that will be included in gametes Recombination leads to new combinations of genes that will be included in gametes The increase in genetic variability insures the ability of organisms to adjust to the environment and thereby offers a better possibility of survival of the species. The increase in genetic variability insures the ability of organisms to adjust to the environment and thereby offers a better possibility of survival of the species.

3. Question1 ( con) The increase in genetic variability insures the ability of organisms to adjust to the environment and thereby offers a better possibility of survival of the species. The increase in genetic variability insures the ability of organisms to adjust to the environment and thereby offers a better possibility of survival of the species. This is reshuffling of the genes resulting in new combinations This is reshuffling of the genes resulting in new combinations

4. Question 2 The cytological evidence for crossing over is the presence of synaptinemal complexes The cytological evidence for crossing over is the presence of synaptinemal complexes These are chromosomes connected by chiasma undergoing cross overs These are chromosomes connected by chiasma undergoing cross overs Cross overs involves only two of the four sister chromatids Cross overs involves only two of the four sister chromatids

5. Questions 3 More crossing over occurs between more distantly related genes More crossing over occurs between more distantly related genes Two genes that are at a distant have space for their chromosome arms to cross and thereby insure the possibility of genetic exchange between homologous chromosomes Two genes that are at a distant have space for their chromosome arms to cross and thereby insure the possibility of genetic exchange between homologous chromosomes

6. Question 5 Double cross overs are expected in lower frequencies because Double cross overs are expected in lower frequencies because Two genes must be exchanged simultaneously Two genes must be exchanged simultaneously Cross over events on one chromosome inhibit the cross over events on another chromosome Cross over events on one chromosome inhibit the cross over events on another chromosome

7. Question 8 dp---------------------cl--------ap dp---------------------cl--------ap

8. Question 9 a + b are on separate chromosomes – random assortment takes place and the gametes are formed by independent assortment and segregation a + b are on separate chromosomes – random assortment takes place and the gametes are formed by independent assortment and segregation a+ b are linked and far apart so that crossing over occurs 100% and therefore appears to be like a a+ b are linked and far apart so that crossing over occurs 100% and therefore appears to be like a a + b are linked so that there is no space for the exchange to occur a + b are linked so that there is no space for the exchange to occur A+ b are on the same chromosome about 10 map units apart. They have a total of 10 % crossing over between these two physical points on the chromosome A+ b are on the same chromosome about 10 map units apart. They have a total of 10 % crossing over between these two physical points on the chromosome

9. Question 10 Colored green 88 Colored green 88 Colored yellow 12 Colored yellow 12 Colorless green 8 Colorless green 8 Colorless yellow 92 Colorless yellow 92 Total = 200 Total = 200 Cross overs = 20 Cross overs = 20 20/200 = 10% or 10 map units between the coat color gene and the plant color gene 20/200 = 10% or 10 map units between the coat color gene and the plant color gene

10. Question 13 Order of the genes Order of the genes d---b---pr---vg---c---adp d---b---pr---vg---c---adp 31 48 54 67 75 83 31 48 54 67 75 83

11. Question 15 Order of the genes Order of the genessc---------v----s 33 10 33 10