PS2 Semi Finished Essay

694 Words Nov 17th, 2014 3 Pages
Bios 101, Problem Set 2

These questions are due at the beginning of discussion. The due date is indicated on the syllabus. Please type or print neatly on separate sheets of paper. It is imperative that no portion of your answers be copied directly from another student or from an online source.

1. A man with normal vision marries a woman with normal vision. Their first child, a boy, is color-blind.

i) (one point) Diagram the cross above.

colorblindness: (XxXx= females; XxY=males)

mom:X dad: Y
Since its sex-linked, then you know the father has normal vision, then he has a dominant allele on his X chromosome. Since the color blind child in question is a son, then he inherited a Y from the father. So, the colorblindness
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What type of allelic interactions are these? How many loci are involved? Are there multiple possibilities? Diagram a cross consistent with the data.

ii) List and discuss several traits, in domestic plants of your choosing, that have a similar genetic basis.

3. A line of Drosophila melanogaster with ebony body and sepia eyes (line A) is crossed to a line with tan body and red eyes (line B). The F1 are all tan-bodied, red-eyed.

i) (one point) What proportion of gametes produced by the F1 have the dominant allele for both loci? What proportion of the gametes produced by line B have the d ominant allele for both loci?

Next, imagine that An F1 female is crossed to a male from line A.

If 1000 offspring were scored for both characters, what number of offspring would be expected to have each of the four phenotypes (assuming no linkage)? List them below.

Now imagine that the following data were actually collected from the cross above:

Body Eyes
Tan normal 271
Tan sepia 229
Ebony normal 220
Ebony sepia 280

ii) (one point) Are the loci linked? If so, how many map units are they apart ? Do a χ2 test and show your work below. Diagram this cross.

4. (two points) Go online, and look up two hereditary illnesses that are caused by having two copies of an autosomal recessive allele.
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