Chapter 8 continued

Question 1

Heating to separate DNA

Answer 1

DNA responds to heat by denaturing. losing its hydrogen bonding and thereby separating it into two strands

Question 2

Restriction endonuclease

Answer 2

They make staggered symmetrical cuts that leave short tails called “sticky ends” Cut four to five bases on the 3’ strand and on the 5’ strand.

Question 3

cDNA

Answer 3

made from mRNA, tRNA, and rRNA. splicing removes the introns from the precursor mRNA generating mRNA

Question 4

How cDNA is used

Answer 4

to synthesize eukaryotic genes from mRNA transcripts and is free from introns

Question 5

ligase

Answer 5

used in the final splicing of genes into plasmids and chromosomes. necessary to seal the sticky ends together

Question 6

DNA sequencing

Answer 6

Determining the exact genetic code.

Question 7

Nucleic acid hybrization

Answer 7

used to identify bacterial species by analyzing sequences of nitrogenous bases in DNA.

Question 8

gene probes

Answer 8

small fragments of single stranded DNA or RNA complementary to the specific DNA sequence of a particular microbe. know it is complementary to the gene you’re looking for.

Question 9

FISH

Answer 9

Peptide nucleic acid FISH testing. the blood culture is flooded with a fluorescent probe. turns the bacteria fluorescent. using genetics to identify bacteria.

Question 10

what does PCR do?

Answer 10

PCR rapidly increases the amount of DNA in a sample without the need for making cultures or carrying out complex purification techniques.

Question 11

Parts of PCR test

Answer 11

• Primers- DNA strands about 15 to 30 bases long that serve as landmarks of where DNA amplification should begin.
• “Taq” polymerase remains active at elevated temperatures used in PCR.
• Thermal cycler automatically preforms the cyclic temperature changes required for PCR.

Question 12

General steps of PCR

Answer 12

1. Denaturation- heating the target DNA to separate it into two strands
2. Priming- primers are added in concentration that favors binding to the complementary strand of test DNA.
3. Extension- DNA polymerase and nucleotides are added at the free end of each primer.

Question 13

Goals of clinical microbio

Answer 13

• identify the causative agent (if any)

- characterize the pathogen

Question 14

3 methods of identifying bacteria

Answer 14

• phenotypic
• genotypic
• immunologic

Question 15

microscopy

Answer 15

• microscopic- light microscopy aids in the observation of the morphology.
• macroscopic - traits that can be assessed with the naked eye.

Question 16

colony morphology

Answer 16

texture, size shape and pigment of the colony.

Question 17

biochemical testing

Answer 17

test metabolic activities (ex. fermentation) , and specific enzymes (ex. catalase)

Question 18

antimicrobial sensitivity testing

Answer 18

A sample from the infected site is cultured on a media to recover the bacteria or fungus causing the infection and it is done to find the best type of antibiotic to use

Question 19

MALDI-TOF

Answer 19

what we do at UIHC, take a sample and laser it, it will then spread the gel across the electric field generator and looks at the time of the flight tube to the detector then compares the unknown sample to the known data bank.

Question 20

Advantages of genotypic methods

Answer 20

1. Culturing of microorganisms is not always necessary
2. genotypic methods are increasingly automated, making them more precise
3. viable non-cultured microbes that cant be grown in the lab can be identified by genotypic methods.

Question 21

disadvantages of genotypic methods

Answer 21

1. costly

2. have to know what you’re looking for because you only get yes or no

Question 22

antibody

Answer 22

a blood protein produced in response to and counteracting a specific antigen.

Question 23

antigen

Answer 23

bad guy doesn’t belong. a toxin or foreign substance that doesn’t belong that induces an immune response

Question 24

epitope

Answer 24

the part of an antigen molecule that actually locks to an antibody

Question 25

types of immunologic testing

Answer 25

immunologic testing can either test a sample for presence of antibodies or antigens.

Question 26

what tests fall under immunologic testing

Answer 26

1. immunofluorescence - tests for antigen, patients sample is mixed with a fluorescent tag, if positive, the sample fluoresces.
2. The coagulase test and serology test, clumps them
3. Western blot- tests for antibodies, known viral proteins are separated by size on a protein gel. if positive the sample emits the respective signal.

Question 27

direct ELISA’s (immunlogic)

Answer 27

tests for antigen, patients sample is mixed with an antibody labeled with an enzyme that produces color, if positive the sample changes color.

Question 28

indirect ELISA’s (immunlogic_

Answer 28

test for antibodies, the patients sample is mixed with an antibody labeled with an enzyme that produces color. if positive the sample changes color.

Question 29

Genetic engineering

Answer 29

manipulating DNA in order to make an organism preform new processes

Question 30

biotechnology

Answer 30

the use of microorganisms, cells, or cell components to make a product

Question 31

restriction fragments

Answer 31

pieces of DNA produced by restriction endonuclease