Topic 10 pt 2: Mapping Flashcards

1
Q

What did Thomas Hunt Morgan do

A

Developed the idea that physical distance between linked genes are related to their recombination rates

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2
Q

Genetic map vs physical map vs map units

A

Genetic map: generated using RF

Physical map: actual physical distance in bp

Map units: centiMorgans (cM), 1cM = 1 RF (for genetic maps)

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3
Q

What can we not distinguish between in terms of recombination

A

Unlinked genes on different chromosomes and unlinked genes that are just very far apart on the same chromosome

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4
Q

Parental/recombinant ratio in progeny for unlinked gene

A

50/50

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5
Q

When will mapping distance be underestimated? Why?

A

For genes that are far apart but linked
Due to double cross overs between them (slide 7)

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6
Q

Slide 8, 10

A

Linkage and non linkage, genetic map calculation

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7
Q

Why construct a genetic map with a three-point testcross (4)

A
  1. more efficient mapping technique
  2. order of the three genes can be established in a set of progeny
  3. some double crossovers can be detected
  4. more accurate map distances
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8
Q

Slide 13-16

A

Genetic map with three-point testcross

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9
Q

Steps in determining gene order in a three point cross (4)

A
  1. Identify the nonrecombinant progeny (two most numerous phenotypes)
  2. Identify the double-crossover progeny (two least numerous phenotypes)
  3. Compare phenotypes of double crossover and nonrecombinant progeny. Should be alike in two characteristics and differ in one.
  4. Characteristic that differs btw nonrecombinant and double crossover progeny is encoded BY THE MIDDLE GENE
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10
Q

Slide 20***

A

RF calculations

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