Micro 2- Diagnostic Micro

Question 1

what is a plasmid?

Answer 1

self-replicating circular pieces of DNA

-often code for proteins that enhance the pathogenicity of a bacterium

Question 2

conjugative plasmid

Answer 2

carries genes for sex pili and transfer of the plasmid

Question 3

dissimilation plasmids

Answer 3

encode enzymes for the catabolism of unusual compounds

Question 4

resistance factors (R factors)

Answer 4

encode antibiotic resistance

Question 5

what are transposons?

Answer 5

segments of DNA that can move one region of DNA to another

Question 6

transposons contain

Answer 6

insertion sequences (IS) that code for transposes that cuts and reseals DNA

Question 7

what is special about complex transposons

Answer 7

they carry other genes (e.g. in antibiotic resistance)

Question 8

what are morphological characteristics?

Answer 8

useful for identifying eukaryotes, tell little about phylogenic relationships

Question 9

what is differential staining used for?

Answer 9

gram staining, acid-fast staining, not useful for bacteria without cell walls

Question 10

what can biochemical tests identify about microorganisms?

Answer 10

determine presence of bacterial enzymes

Question 11

a fermentation test shows

Answer 11

bacteria that catabolize carbohydrate or potion produce acid, causing the pH indicator to change color

Question 12

oxidase tests for

Answer 12

identifies bacteria that have cytochrome oxidase (e.g. Neisseria gonorrhoeae, pseudomonas)

Question 13

what are rapid identification methods?

Answer 13

perform several biochemical tests simultaneously

-results of each test are assigned a number

Question 14

what is serology

Answer 14

the science that studies serum and immune responses in serum

Question 15

what does “microorganisms are antigenic” mean?

Answer 15

they stimulate the body to form antibodies

Question 16

antiserum-

Answer 16

a solution of antibodies is tested against an unknown bacterium

Question 17

what occurs in a slide agglutination test

Answer 17

bacteria agglutinate when mixed with antiserum-containing antibodies produced in response to that species/strain

Question 18

enzyme linked immunosorbent assay (ELISA)

Answer 18

known antibodies and an unknown type of bacterium are added to a well
-a reaction identifies the bacteria

Question 19

western blotting

Answer 19

identifies antibodies in a patient’s serum, confirms HIV infection

Question 20

what is phage typing?

Answer 20

test for determining which phages a bacterium is susceptible to

Question 21

procedure of phage typing

Answer 21

• stain in question is grown over entire plate
• a drop of different phage type is placed on bacteria
• clearning called plaques appear where phages infect and lyse bacterial cells

Question 22

example of how phage typing can be used- specific genus/family

Answer 22

used to distinguish S. enterica serotypes and S. aureus types

Question 23

nucleic acid analysis via DNA base composition tests for

Answer 23

• percentage of guanine + cytosine

- two organisms that are closely related have similar amounts of various bases

Question 24

nucleic acid analysis via DNA fingerprint tests for

Answer 24

• electrophoresis of restriction enzymes digests an organism’s DNA
• comparing fragments from different organisms provides information on genetic similarities and differences

Question 25

how do nucleic acid amplification tests work

Answer 25

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

Question 26

how does nucleic acid hybridization work

Answer 26

measures the ability of DNA strands from one organism to hybridize with DNA strands of another organism
(greater degree of hybridization, greater degree of relatedness)

Question 27

southern blotting uses

Answer 27

uses nucleic acid hybridization to identify unknown microorganisms using DNA probes

Question 28

what does a DNA chip (microarray) contain, and what is its function

Answer 28

contains DNA probes and detects pathogens by hybridization between the probe and DNA in the sample

Question 29

two types of DNA chip (microarray)

Answer 29

• ribotyping

- fluorescent in situ hybridization (FISH)

Question 30

ribotyping

Answer 30

rRNA sequencing 
(type of DNA chip-microarray)

Question 31

fluroescent in situ hybridization (FISH)

Answer 31

fluroescent DNA or RNA probes stain the microorganisms being targeted