how does conjugation work? fig. 14.9 fig. 14.11

How does conjugation work?

Fig. 14.9

Fig. 14.11

Fig. 14.12a

Fig. 14.12b

Fig. 14.13

Fig. 14.14

Fig. 14.15

Fig. 14.16

Fig. 14.17

What question did Tatum and Lederberg set out to answer?

What led them to expect bacteria exchanged genetic information?

Why did he pick the bacteria (E. coli)he used as starting material?

Why did Lederberg want to use multiplemutations?

How did he get multiple mutations?

What kind of mutations are made by X-rays And what kind by UV light?

B- M- P+ T+ and B+ M+ P- T-culture together

Get 102/109 prototrophs:

B+ M+ P+ T+

What did Lederberg do to get recombinants?

Other possible explanations

Cross feeding (syntropism)limiting dilution plating

Transformationmixed culture media with each parental type

After conjugation what are the most common products?

What do the rare classes represent?

Did recombination occur in both directions?

Did all possible parental combinationslead to prototrophs?

What must E. coli K12 have for Lederberg’sExperiments to have worked?

Why is frequency of prototrophs so low?

Is this recombination mechanism equivalent to sexual recombination in eukaryotes?