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Tetrad analysis. Fig 5.15. Nonparental = recombinant . Tetrad analysis. What if two crossovers?. Four recombinants Two recombinants No recombinants. Fig 5.15. Parental ≠ non-recombinant. Fig. 5.17. Centromere is not a mutation. But you can still use it for mapping. Fig. 5.21.

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Presentation Transcript
slide1

Tetrad analysis

Fig 5.15

Nonparental = recombinant

slide2

Tetrad analysis

What if two crossovers?

Four recombinants

Two recombinants

No recombinants

Fig 5.15

slide4

Centromere is not a mutation

But you can still use it for mapping

Fig. 5.21

slide6

Morgan

Bridges

Muller

Sturtevant

muller s x ray experiment10
Muller’s X-ray experiment

Created XClB

•XY

gametes

muller s x ray experiment11
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

muller s x ray experiment12
Muller’s X-ray experiment

Created XClB

•XY x XClBX

(Bar-eyed females)

gametes

muller s x ray experiment13
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

(ignore males)

muller s x ray experiment14
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

muller s x ray experiment15
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB

muller s x ray experiment16
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB

•XY, XClBY

(ignore females)

muller s x ray experiment17
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB

•XY, XClBY

(lethal)

muller s x ray experiment18
Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB

•XY, XClBY

How many lethal mutations?

(lethal)

muller s x ray experiment19
Muller’s X-ray experiment

•XY, XClBY

How many lethal mutations?

(lethal)

muller s x ray experiment20
Muller’s X-ray experiment

•XY, XClBY

How many lethal mutations?

(lethal)

Nobel prize to Muller, 1946: “for the discovery of the production of mutations by means of X-ray irradiation”

george beadle edward tatum 1941
George Beadle & Edward Tatum (1941)

Do mutations affect biochemistry or only death, wing shape, pea color, etc?

bread mold
Bread mold

Fig. 5.14

beadle tatum
Beadle & Tatum

Complete med

Minimal med

beadle tatum25
Beadle & Tatum

(why?)

Complete med

Minimal med

beadle tatum26
Beadle & Tatum

Complete med

Minimal med

Complete med

beadle tatum27
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

beadle tatum28
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + alanine

beadle tatum29
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + serine

beadle tatum30
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + B6

beadle tatum31
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

What’s wrong with the strain?

It can use everything but B6

It can make everything but B6

It can grow on everything but B6

Minimal + B6

beadle tatum32
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

(what is a vitamin?)

Minimal + B6

beadle tatum33
Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

pdx strain

Minimal + B6

beadle tatum36
Beadle & Tatum

Now…how many mutations cause pdx?

beadle tatum37
Beadle & Tatum

pdx x WT

(Haploid)

(Haploid)

beadle tatum38
Beadle & Tatum

(if single-gene, what do we expect?)

pdx x WT

beadle tatum44
Beadle & Tatum

Failure to make B6 segregates 1:1

beadle tatum45
Beadle & Tatum

Failure to make B6 segregates 1:1

so…

mutation in a single gene

beadle tatum46
Beadle & Tatum

Failure to make B6 segregates 1:1

so…

mutation in a single gene

so…

Step in B6 synthesis attributed to a single gene

“One-gene-one-enzyme”

beadle tatum47
Beadle & Tatum

Failure to make B6 segregates 1:1

so…

mutation in a single gene

so…

Nobel prize to Beadle & Tatum, 1958: “for their discovery that genes act by regulating definite chemical events”

beadle tatum48
Beadle & Tatum

Not quite one-gene-one-enzyme:

Fig. 9.1

“One-gene-one-polypeptide”

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