Diagnostic Micro

Question 0

Gram stains are important because

Answer 0

It gives the relative abundance - double checks that everything grew

Question 1

Diagnostic Microbiology is focused on the study of what?

Answer 1

Bacterial pathogens

Question 2

What is purulence?

Answer 2

Pus

Question 3

How are gram stains used as a diagnostic tool from a primary sample?

Answer 3

Confirm physician suspicion of etiology of infection
Aid in correct antibiotic selection
Screen adequacy of specimen
Identify cellular components & debris of inflammation
Presumptive diagnosis

Question 4

What are some examples of primary cultures?

Answer 4

Smears from swabs
Smears from thick liquids
Smears from thick mucoid material
Smears from thin fluids

Question 5

What is the cytospin used for?

Answer 5

Thin fluids with low cellularity

Question 6

What does the cytospin do?

Answer 6

Maximize cell recovery from a liquid & deposit the sediment on a slide

Question 7

How do you make a smear from a plate?

Answer 7

Emulsify material in a drop of water on a slide

Question 8

What does PMN stand for?

Answer 8

Poly morphonuclear leukocytes

Question 9

What is an example of contaminatin of a sample?

Answer 9

Epithelial cells

Question 10

What is quality control?

Answer 10

When known positive & negatives are stained

Direct gram stain from primary sample better match what grows on the plates - internal control

Question 11

Is there a larger peptidoglycan layer in gram-positive or gram-negative bacteria?

Answer 11

Gram-positive

Question 12

Do endotoxins stain gram positive or negative?

Answer 12

Gram-negative

Question 13

The peptidoglycan layer consists of what two alternating peptides?

Answer 13

NAG & NAM

Question 14

The NAG & NAM chains are cross-linked to form a thick network of what?

Answer 14

Peptide bridge connected to the tetra-peptides on the NAM

Question 15

What are two special acids that are part of gram-positive cell walls?

Answer 15

Teichoic acid & lipo-techoic acid

Question 16

Are gram-negative cell walls thick or thin?

Answer 16

Thin

Question 17

What type lipid is an endotoxin?

Answer 17

Lipid A

Question 18

What is endotoxin responsible for?

Answer 18

Producing fever & shock in patients infected with gram-negative bacteria

Question 19

What is the outer membrane of gram-negative bacteria a barrier to?

Answer 19

Hydrophobic compounds

Question 20

What does the outer membrane do?

Answer 20

It is a sieve

Allows water soluble molecules to enter through porins

Question 21

What are porins & what do they do?

Answer 21

Protein lined channels

Provides attachment sites that enhance attachment to host cells

Question 22

What gets released and becomes endotoxins?

Answer 22

Lipopolysaccharides

Question 23

What is chromosomal DNA?

Answer 23

One circular supercoiled ds DNA

Question 24

What are plasmid (extrachromosomal) DNA?

Answer 24

Non-essential circular supercoiled DNA fragments - low or high copy Copied to daughter cells & spread by conjugation

Question 25

What are three mobile genetic elements present in bacterial DNA?

Answer 25

Insertion sequences Transposons Cassettes

Question 26

What are insertion sequences?

Answer 26

Short DNA that code for transposase | They may jump into a gene & activate or inactivate it

Question 27

What are transposons?

Answer 27

Longer pieces of DNA that are mobile & have more genes | An example is antibiotic resistance

Question 28

What are cassettes?

Answer 28

More sophisticated DNA inserts with multiple genes & regulatory elements

Question 29

How big is a bacterial chromosome?

Answer 29

2.8 Mb

Question 30

What is he size of a plasmid?

Answer 30

˜5 Kb

Question 31

What is the size of an insertion sequence?

Answer 31

1000 bp

Question 32

What is the size of an SCC cassette in MRSA?

Answer 32

20.9 to 66.0 kb

Question 33

What are three types of genome change?

Answer 33

Antibiotic resistance Mutations Genetic recombination

Question 34

How does the genome change to spread antibiotic resistance?

Answer 34

Acquisition of plasmids & other forms of mobile genetic elements that spread the antibiotic resistance

Question 35

What are the types of mutations that causes genome change?

Answer 35

Point - one base Frameshift - disrupts amino acid sequence Deletions Insertions from mobile elements

Question 36

Where is the genome change caused by genetic mutation?

Answer 36

Between 2 DNA molecules

Question 37

What are the three mechanisms of gene transfer?

Answer 37

Transformation Transduction Conjugation

Question 38

What is transformation?

Answer 38

Uptake & incorporation of naked DNA from the environment | Cells must be competent to take it up

Question 39

What is transduction?

Answer 39

Transfer of genes by bacteriophage | Genes are incorporated into genome - lysogengy

Question 40

What is conjugation?

Answer 40

DNA from a donor strain integrates into the genome

Question 41

Which mechanism admires the naked form?

Answer 41

Transformation

Question 42

Which mechanism has conjugal visits?

Answer 42

Conjugated

Question 43

Which mechanism duct tapes viruses into the bacteria?

Answer 43

Transduction

Question 44

What does eukaryote mean?

Answer 44

True nucleus

Question 45

What is the structure of chromosomes in eukaryotic cells?

Answer 45

Linear complexed with histones & proteins

Question 46

What are present in extrachromosomal DNA?

Answer 46

Mitochondria & chloroplasts

Question 47

Eukaryotic have what components that are not present in prokaryotic cells?

Answer 47

Membrane bound organelles | Endoplasmic reticulum