Midterm 2 - Notes 2 (Part 3)

Question 1

What does phage typing do?

Answer 1

It is a test for determining which phages a bacterium is susceptible to

Question 2

Where do plagues occur

(clearings)?

Answer 2

They occur where phages infect and lyse bacterial cells

Question 3

FAME

Answer 3

Fatty acid methyl ester

Question 4

What does FAME provide?

Answer 4

It provides profiles that are constant for a particular species

Question 5

What does flow cytometry do?

Answer 5

It uses differences in electrical conductivity between species or fluorescence

Question 6

What are the 7 phases of flow cytometry?

Answer 6

1. A mixture of cells is treated to label cells that have certain antigens with fluorescent-antibody markers
2. Cell mixture levels nozzle in droplets
3. Laser beam strikes each droplet
4. Fluorescence detector identifies fluorescent cells by fluorescent light emitted by cell
5. Electrode gives positive charge to identified cells
6. As cells drop between electrically charged plates, the cells with a positive charge move closer to the negative plate
7. The separated cells fall into different collection tubes

Question 7

DNA base consumption

Answer 7

Tells you what % of guanine and cytosine there is

Question 8

DNA fingerprinting

Answer 8

Compares fragments from different organisms that provide information on genetic similarities and differences

Question 9

NAATs

Answer 9

Nucleic acid amplification tests

Question 10

What do NAATs do?

Answer 10

They use PCR to amplify DNA of an unknown microorganism that cannot be cultured

Question 11

Nucleic acid hybridization

Answer 11

Measures the ability of DNA strands from one organism to hybridize with DNA strands of another organisms
- greater degree of hybridization the greater degree of relatedness

Question 12

What are the 4 phases in nucleic acid hybridization?

Answer 12

1. Heat to separate strands
2. Combine single strands of DNA
3. Cool to allow renaturation of double stranded DNA
4. Determine degree of hybridization

Question 13

What does souther blotting use?

Answer 13

It uses nucleic acid hybridization to identify unknown microorganisms using DNA probes

Question 14

What are the 7 DNA probing identification steps?

Answer 14

1. A salmonella DNA fragment is cloned in E. coli
2. Cloned DNA fragments are marked with fluorescent dye and separated into single strands, forming DNA probes
3. Unknown bacteria are collected on a filter
4. The cells are lysed and the DNA is released
5. The DNA is separated into single strands
6. DNA probes are added to the DNA from the unknown bacteria
7. DNA probes hybridize with salmonella DNA from sample
   - then the excess probe is washed away
   - fluorescents indicates presence of salmonella

Question 15

What is another word for DNA chips?

Answer 15

Microarrays

Question 16

What do DNA chips do?

Answer 16

They contain DNA probes and detects pathogens by hybridization between the probe and DNA in the sample
- detected by fluorescence

Question 17

Ribotyping

Answer 17

Probing bacterial genome with 16s rRNA gene probe

Question 18

FISH

Answer 18

Fluorescent in situ hybridization

Question 19

What does FISH do?

Answer 19

Determines the identity, abundance and relative activity of microorganisms in an environment
- use fluorescents DNA and RNA probes to stain the targeted microorganisms

Question 20

Dichotomous key

Answer 20

Identification keys based on successive questions

Question 21

Cladograms

Answer 21

Maps that show evolutionary relationships among organisms

- based on rRNA sequences