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Diploid Life Cycles

Haploid Life Cycles

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WHAT DO GENES DO? 

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Beadle and Tatum - ONE GENE-ONE ENZYMEused Neurospora; defined minimal media for Neurospora growth

(salts and sugar). Isolated mutants which could not grow inminimal media, but could grow in complete media (salts, sugar,amino acids, vitamins). Haploid organism. 

 Auxotroph – needs supplement to grow on minimal mediaPrototroph – wild-type that needs no supplement; cansynthesize all required growth factors

can define what extra the mutant needs to grow (what gene it is

mutated in) isolated many arg- mutations (requires arginine to grow)mutations mapped to 3 different locations

WHAT DO GENES DO? 

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Ornithine Citrulline Arginine

+ + +

- + +

- - +

arg-

arg-!

arg-"

Precursor ornithine citruline arginine#nz$ A #nz$ % #nz$ C

!eadle a"d Ta#$% & ONE GENE&ONEEN'()E

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Ornithine Citrulline Arginine+ + +

- + +

- - +

arg-

arg-!

arg-"

Precursor ornithine citruline arginine#nz$ A #nz$ % #nz$ C

&he ta'le shows the growth characteristics for three #$ coli

strains that are each auxotrophic for a different gene requiredfor arg 'iosynthesis$

($ )s arg-" mutant in #nz$ A* #nz$ % or #nz$ C

!eadle a"d Ta#$% & ONE GENE&ONEEN'()E

Clicker Question #32

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Factors A, B, C, D control the production of a black pigment. The genes

encoding A, B, C and D are independently assorting. The alternate alleles that

give abnormal function of these genes are a, b, c, and d. A black AA BB CC

DD is crossed with a colorless aa bb cc dd to give a black F1. The F1 is then

backcrossed with a colorless aa bb cc dd. Assume that A, B, C and D act in a

pathway as follows:

 A % C ,

colorless colorless grey 'rown 'lac.

What percentage of the F2 are grey?

A. 1/4

B. 1/6

C. 1/8

D. 1/16

E. None of above

!eadle a"d Ta#$% & ONE GENE&ONEEN'()EClicker Question #33

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+&, Video 6

-"#e.p.e#a#io" of !eadle a"d Ta#$%e/pe.i%e"#s

/ Eac0 e"e co"#.ols #0e sy"#0esis of a" e"y%e i"oledi" ca#alyi" #0e co"e.sio" of a" i"#e.%edia#e i"#o

a.i"i"e4

/ ONE GENE 5 ONE EN'()E