Lecture 9

Question 1

What is an Exogenote?

Answer 1

Part of DNA from the Hfr donor recipient

Question 2

What is an Endogenote?

Answer 2

DNA from F- recipient (complete genome)

Question 3

What kind of cross is required for DNA to inter-grate after transfer

Answer 3

A double cross over or even number of cross overs

Question 4

What is the purpose of High Resolution Mapping by Recombination Frequency?

Answer 4

To determine distance between markers

Question 5

In High Resolution Mapping by Recombination Frequency which marker do you select for?

Answer 5

The last marker to enter, then screen for the earlier markers

Question 6

What does the frequency of recombination classes depend on?

Answer 6

The order of genes and distance between each pair of genes

Question 7

In examples of crossovers, what will the most rare class tell us about where the gene was excisesd?

Answer 7

Tells us the gene was excised in the middle

Question 8

How many base pairs does the K12 strain have?

Answer 8

4 million

Question 9

How many transposable elements does E.Coli have?

Answer 9

48

Question 10

How many genes in E.coli, and how many have experimentally determined functions?

Answer 10

1. ~4200 genes

2. 2/3 experimentally determined

Question 11

Describe how genes of related function are arranged in E.Coli

Answer 11

They are often clustered together into operons

Question 12

How do E.Coli isolates differ from benign isolates?

Answer 12

By presence of plasmids and clusters of horizontally acquired virulence genes

Question 13

Describe the Repeated U-Tube experiment by Lederberg and what they found

Answer 13

• 2 singular strains wouldn’t produce any colonies but when combined prototrophs were produced.
• Cell to cell contact WASN’T required because gene transfer occurred through a filterable agent which was a bacteriophage.

Question 14

Describe the mechanism of generalised transduction

Answer 14

1. Some lytic bacteriophage inject genome into a donor bacteria, taking over the host machinery
2. Phage particles assemble in the cell
3. Phages burst out and continue to the next cell

Question 15

TRUE or FALSE

Any gene in the chromosome has a chance of being transduced

Answer 15

TRUE

Question 16

Finish the sentence

The amount of transducable DNA is limited by …

Answer 16

The amount of DNA packed into phage head

Question 17

What is the phage host determined by?

Answer 17

The cell surface receptors

Question 18

TRUE or FALSE

Phage have a wide host range

Answer 18

FALSE

Phage have a narrow host range, they transduce into the same species

Question 19

What can be determined based on the amount of DNA packaged into the phage head?

Answer 19

How close the genes are based on if they’ll be transduced