III Linkage A Complete Linkage B Incomplete Linkage

III. Linkage A. ‘Complete’ Linkage B. ‘Incomplete’ Linkage C. Three-point Mapping - combine complementary sets ABC = 25 abc = 27 52 ABc = 3 ab. C = 5 = 8 Abc = 42 a. BC = 39 81 Ab. C = 85 a. Bc = 79 164 Three Point Test Cross Aa. Bb. Cc x aabbcc Phenotypic Ratio: ABC ABc Ab. C a. Bc ab. C = = = = 25 3 42 85 79 39 27 5

Bacterial Genetics Copyright © 2010 Pearson Education, Inc.

Bacterial Genetics I. Overview - Domains of Life Copyright © 2010 Pearson Education, Inc.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission = 10 billion cells

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission The rapid production of new organisms creates genetic diversity by mutation, alone; even though the rates of mutation are low for any given gene. Consider an average gene mutation rate = 1 x 10 -5 (meaning a new mutation is produced in every 100, 000 copies… or descendants). In 10 billion (1010) descendants, there would be 105 different mutations at this one gene. This is happening independently across 4000 (4 x 103) genes in the E. coli genome. So, in that population of 10 billion cells, there might be as many as 4 x 108 different genomes. About 1/3 will be “silent” (not change the AA), and many will result in a lethal mutation so they won’t occur. But still…. . VARIATION.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission B. “sex” – genetic recombination 1. conjugation

Lederberg and Tatum – 1946 - certain strains of bacteria are able to donate genes to other strains – they have a “fertility factor” (F+). Other strains lack this factor (F-).

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission B. “sex” – genetic recombination 1. conjugation Davis demonstrated that cell contact was required… Copyright © 2010 Pearson Education, Inc.

And Cavalli Sforza isolated a strain that would cause genetic change at a very high rate: Hfr (High frequency recombination). He recognized that the acquisition of traits was related to the duration of the conjugation event. Copyright © 2010 Pearson Education, Inc. Figure 8 -6

He hypothesized that the time between transfer to the recipient cell was related to the distance between genes. As such, if he interrupted mating at specific intervals, he could use time between trait acquisition as an index of distance between genes. Copyright © 2010 Pearson Education, Inc.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission B. “sex” – genetic recombination 1. conjugation He isolated different strains that transferred genes in different order, suggesting that the transfer process could begin at different places. Copyright © 2010 Pearson Education, Inc.

He isolated different strains that transferred genes in different order, suggesting that the transfer

Figure 8 -9 part 1 Copyright © 2010 Pearson Education, Inc.

Figure 8 -9 part 2 Copyright © 2010 Pearson Education, Inc.

Figure 8 -9 part 3 Copyright © 2010 Pearson Education, Inc.

Figure 8 -9 part 4 Copyright © 2010 Pearson Education, Inc.

Figure 8 -9 part 5 Copyright © 2010 Pearson Education, Inc.

An integrated Hfr plasmid can revert to a free F+ plasmid, and take chromosomal

Figure 8 -10 part 4 Copyright © 2010 Pearson Education, Inc.

Figure 8 -10 part 5 Copyright © 2010 Pearson Education, Inc.

video

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission B. “sex” – genetic recombination 1. conjugation 2. transformation – absorption of DNA from the environment.

Figure 8 -12 part 1 Copyright © 2010 Pearson Education, Inc.

Figure 8 -12 part 2 Copyright © 2010 Pearson Education, Inc.

Figure 8 -12 part 3 Copyright © 2010 Pearson Education, Inc.

Figure 8 -12 part 4 Copyright © 2010 Pearson Education, Inc.

Figure 8 -12 part 5 Copyright © 2010 Pearson Education, Inc.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction A. fission B. “sex” – genetic recombination 1. conjugation 2. transformation – absorption of DNA from the environment. 3. viral transduction

Figure 8 -14 Copyright © 2010 Pearson Education, Inc.

Figure 8 -17 Copyright © 2010 Pearson Education, Inc.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology

Bacterial Genetics Plasmid ‘vector’ with ampicillinresistance gene I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology

Bacterial Genetics Plasmid ‘vector’ with ampicillinresistance gene I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology Transformation: absorption of plasmids

Bacterial Genetics Plasmid ‘vector’ with ampicillinresistance gene I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology Transformation: absorption of plasmids Grow on selective media with ampicillin; only bacteria that have absorbed plasmids will grow.

Bacterial Genetics Plasmid ‘vector’ with ampicillinresistance gene I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology Transformation: absorption of plasmids Grow on selective media with ampicillin; only bacteria that have absorbed plasmids will grow. Fission produces millions of cells in a day that have each plasmid – colonies.

Bacterial Genetics I. Overview - Domains of Life II. Prokaryotic Reproduction III. The Use of Bacteria in Recombinant DNA Technology Show the location of all ampicillin -resistant colonies Transfer to a piece of filter paper with a radiolabeled probe specific to the gene in question Take an x-ray to identify colonies that have absorbed the plasmid with the gene of interest. Culture the bacteria, cloning the gene for study.