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Tetrad analysis


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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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Tetrad analysis

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Slide1 l.jpg

Tetrad analysis

Fig 5.15

Nonparental = recombinant


Slide2 l.jpg

Tetrad analysis

What if two crossovers?

Four recombinants

Two recombinants

No recombinants

Fig 5.15


Slide3 l.jpg

Parental ≠ non-recombinant

Fig. 5.17


Slide4 l.jpg

Centromere is not a mutation

But you can still use it for mapping

Fig. 5.21


How do we know that radiation causes genetic defects l.jpg

How do we know that radiation causes genetic defects?


Slide6 l.jpg

Morgan

Bridges

Muller

Sturtevant


Muller s x ray experiment 1928 l.jpg

Muller’s X-ray experiment (1928)


Muller s x ray experiment l.jpg

Muller’s X-ray experiment

Created XClB


Muller s x ray experiment9 l.jpg

Muller’s X-ray experiment

Created XClB

XY


Muller s x ray experiment10 l.jpg

Muller’s X-ray experiment

Created XClB

•XY

gametes


Muller s x ray experiment11 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes


Muller s x ray experiment12 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

(Bar-eyed females)

gametes


Muller s x ray experiment13 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

(ignore males)


Muller s x ray experiment14 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB


Muller s x ray experiment15 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB


Muller s x ray experiment16 l.jpg

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 l.jpg

Muller’s X-ray experiment

Created XClB

•XY x XClBX

gametes

•XX, •XXClB

XY x •XXClB

•XY, XClBY

(lethal)


Muller s x ray experiment18 l.jpg

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 l.jpg

Muller’s X-ray experiment

•XY, XClBY

How many lethal mutations?

(lethal)


Muller s x ray experiment20 l.jpg

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”


Important for radiation biology but also for basic genetics l.jpg

Important for radiation biology, but also for basic genetics


George beadle edward tatum 1941 l.jpg

George Beadle & Edward Tatum (1941)

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


Bread mold l.jpg

Bread mold

Fig. 5.14


Beadle tatum l.jpg

Beadle & Tatum

Complete med

Minimal med


Beadle tatum25 l.jpg

Beadle & Tatum

(why?)

Complete med

Minimal med


Beadle tatum26 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med


Beadle tatum27 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med


Beadle tatum28 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + alanine


Beadle tatum29 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + serine


Beadle tatum30 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

Minimal + B6


Beadle tatum31 l.jpg

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 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

(what is a vitamin?)

Minimal + B6


Beadle tatum33 l.jpg

Beadle & Tatum

Complete med

Minimal med

Complete med

Minimal med

pdx strain

Minimal + B6


Beadle tatum34 l.jpg

Beadle & Tatum


Beadle tatum35 l.jpg

Beadle & Tatum


Beadle tatum36 l.jpg

Beadle & Tatum

Now…how many mutations cause pdx?


Beadle tatum37 l.jpg

Beadle & Tatum

pdx xWT

(Haploid)

(Haploid)


Beadle tatum38 l.jpg

Beadle & Tatum

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

pdx xWT


Beadle tatum39 l.jpg

Beadle & Tatum

pdx xWT


Beadle tatum40 l.jpg

Beadle & Tatum

pdx xWT


Beadle tatum41 l.jpg

Beadle & Tatum

pdx xWT


Beadle tatum42 l.jpg

Beadle & Tatum

pdx xWT


Beadle tatum43 l.jpg

Beadle & Tatum

pdx xWT


Beadle tatum44 l.jpg

Beadle & Tatum

Failure to make B6 segregates 1:1


Beadle tatum45 l.jpg

Beadle & Tatum

Failure to make B6 segregates 1:1

so…

mutation in a single gene


Beadle tatum46 l.jpg

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 l.jpg

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 l.jpg

Beadle & Tatum

Not quite one-gene-one-enzyme:

Fig. 9.1

“One-gene-one-polypeptide”