Week 3 - Bacterial Genetics and Microbial Diagnosis - Ziegler

Question 1

4 ways that gene transfer can occur in bacteria?

Answer 1

1 - Transformation - Cell takes up chromosomal DNA from a naked cell that has died
2 - Conjugation - Chromosomal DNA transferred through pilus
3 - Transduction - Bacterial phage transfers DNA from a dead host to a living host
4 - Transposition - Transfer of DNA sequences from one DNA site to another, plasmid to chromosomal or visa versa

Question 2

Man-made use for trasnformation?

Answer 2

Can get bacteria to take up human DNA and synthesize a useful human product

Question 3

Explain what F factors mean in conjugation

Answer 3

Males have F factor and express F pili
Found in 1 of 3 places:
-Integrated in host bacterial chromosome (Hfr)
-Free in cytoplasm (F+)
-Very similar to F+, but also has a part of the bacterial chromosome DNA along with it due to improper excision

Question 4

Why would adding a single F+ bacterium in the middle of a bunch of F- make all the bacteria become F+

Answer 4

When F+ conjugates, it basically only exchanges the F factor. So basically it just converts any bacteria is meets to an F+, and this spreads quickly as they do the same.

Question 5

What causes F factors to integrate at specific sites?

Answer 5

-F factors contain a transposon.
-Transposons are sequences of DNA that can hop around on complementary DNA sequences.
0There are a limited number of sites recognized by transposons, so the F factor hang around them.

Question 6

What kinds of antibiotic resistance traits can bacteria acquire?

Answer 6

-altering number of porins
(dec uptake or inc efflux)
-altering site that the antibiotic targets
(changing penicillin-binding protein)
-acquiring ability to destroy or modify antibiotic
(beta-lactamase destroys penicillin)

Question 7

What is responsible for the toxin produced by diptheria?

Answer 7

The phage within the diptheria has genetic info coding for toxins to be made.

Question 8

Virulent vs temperate phages?

Answer 8

Virulent - Infect bacteria, replicate and burst

Temperate - These prophages can remain in a lysogenic state, integrated into the cell and dormant. A repressor can be degraded to send the phage into the lytic cycle. Goodnight to the cell after that!

Question 9

Cloning vector key features:

Answer 9

• Add in antibiotic resistance genes so you can easily kill bacteria that didn’t get the cloning vector
• replication initiation sites for prok/euk
• must have a recombination site to integrate into the host

Question 10

Normally you don’t see serum antobodies easrly in infection, and it is difficult to tell the difference between past and current infection. What is one way to tell the difference? Probably NOT on test.

Answer 10

See a lot more IgM’s early on, whereas later you see a build-up of IgG’s

Question 11

TESTS used for serum antibody identifcation?

Answer 11

Complement fixation
Hemagglutination
Latex agglutination
ELISA
Western Blots