BIOL 2300 EXAM 2 NEWEST ACTUAL

BIOL 2300 EXAM 2 NEWEST ACTUAL

EXAM - QUESTIONS AND

DETAILED CORRECT ANSWERS|

VERIFIED

What does intergenic mapping involve? Correct Answer *mapping genes by observing recombination between two different virus genomes*

In a transformation experiment, donor DNA was obtained from a prototroph bacterial strain (a+b+c+ ), and the recipient was a triple auxotroph (a-b-c- ). The following transformant classes were recovered. What general conclusions can you draw about the linkage relationships among the three genes from the transformant classes?

a+b-c-: 180

a-b+c-: 150

a+b+c-: 210

a-b-c+: 179

a+b-c+: 2

a-b+c+: 1

a+b+c+: 3 Correct Answer *The a and b loci are close together,

but both are far from locus c.*

Influenza (the flu) is responsible for approximately 250,000 to 500,000 deaths annually, but periodically its toll has been much higher. For example, the 1918 flu pandemic killed approximately 30 million people worldwide and is considered the worst spread of a deadly illness in recorded history. With highly virulent flu strains emerging periodically, it is little wonder that the scientific community is actively studying influenza biology. In 2007, the National Institute of Allergy and Infectious Diseases completed 1 / 3

sequencing of 2035 human and avian influenza virus strains.Influenza strains undergo recombination as described in this chapter, and they have a high mutation rate owing to the error- prone replication of their genome (which consists of RNA rather than DNA). In addition, they are capable of chromosome reassortment in which various combinations of their eight chromosomes (or portions thereof) can be packaged Correct Answer *These processes provide genetic diversity enabling viral survival as host defenses adapt.*

Which of the following statements about conjugation is true?Correct Answer *DNA is transferred from an F+ cell to an F- cell*

How do we know that specific genes are linked on a single chromosome, in contrast to being located on separate chromosomes? Correct Answer *the genes segregate together during gamete formation*

Imagine that you have joined a genetics lab on campus and want to gain experience mapping genes in Drosophila.

You conduct a series of two-point mapping crosses involving five genes located on chromosome III and obtain the following

percentage of recombinant offspring:

h-cu: 23.5%

eyg-h: 9.0%

eyg-cu: 14.5%

rai-eyg: 18.5%

rai-h: 9.5%

rai-cu: 33.0%

th-cu: 6.8%

th-h: 16.7%

th-eyg: 7.7%

th-rai: 26.2% 2 / 3

Considering that rai is near the end of chromosome III, construct a map of these genes. For (a), (b), (c), and (d), enter the correctly named gene, for example, if you think, eyg goes in blank "d", then enter eyg. Order your genes by their distance to rai, with the gene closest to rai going in blank a and the gene most distant going in blank d. For blanks 1, 2, 3, and 4, enter the map distances for the respective genes. For example, the distance in blank 1 would be the distance between rai and the gene you entered in bla Correct Answer a) *h*

• *eyg*
• *th*
• *cu*

1) *9.5*

2) *9.0*

3) *7.7*

4) *6.8*

The genes for mahogany eyes and ebony body are approximately 25 map units apart on chromosome 3 in Drosophila. Assume that a mahogany-eyed gray bodied female was mated to an red eyed ebony-bodied male and that the resulting F 1 phenotypically wild- type (red eyed, gray bodied) females were mated to mahogany, ebony males to obtain an F 2 generation. Which of the following

phenotypes would be expected in the F 2 offspring? Hint: Really

pay attention to what the question is asking you to cross - approach this in a step-wise fashion and you should be fine.........Correct Answer *red eyed, gray bodied* *mahogeny eyed, gray bodied* *red eyed, ebony bodied* *mahogeny eyed, ebony bodied*

When Morgan carried out crosses involving two X-linked genes in Drosophila, he sometimes observed new phenotypes that were not present in the parents. What did Morgan propose from these

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