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8/18/2019 9 Vid Beadle Tatum
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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