Exam #1: Introduction Flashcards Preview

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Flashcards in Exam #1: Introduction Deck (37):
1

Define Virulence.

Ability of a microorganism to cause disease

2

Define Virulence Factor.

Factors produced by organisms that enable it to infect, cause disease, &/or kill the host

3

What are the distinguishing features of viruses?

- Smallest, 0.03-0.3 um--can be seen w/ EM only
- Obligate intracellular pathogens

4

What are the distinguishing features of bacteria?

- 0.1-10 um
- Simple
- Unicellular
- Prokaryote (lack membrane-bound organelles)
- Reproduce by asexual division

5

What are the distinguishing features of fungi?

- 4-10 um
- More complex
- Eukaryotic
- Reproduce sexually & asexually
- Unicellular or multiceullular

6

What are the distinguishing features of parasites?

- 4um- many meters long (i.e. largest/ longest)
- Most complex microorganisms

7

What are the general features of prokaryotes?

General= lack membrane-bound organelles
- Contain cell wall
- No sterols in cell membrane
- No nuclear membrane
- Single circular DNA w/out histones
- Haploid
- No membrane bound organelles
- Asexual reproduction
- 70S ribosome
- Respiration via cell membrane

8

What are the general features of eukaryotes?

General= contain membrane-bound organelles
- Cell wall absent or composed of chitin
- Cell membrane contains sterols
- Classic nuclear membrane
- Multiple strands of DNA w/ histones
- Diploid
- Sexual & asexual reproduction
- 80S ribosome
- Respiration via mitochondria

9

What are the common methods for identification & classification of bacteria?

1) Microscopy
2) Detection of bacterial antigens
3) Detection of specific bacterial nucleic acids
4) Culture
5) Detection of antibody responses to bacteria

10

What is the H-antigen associated with?

Flagella

11

What is the K-antigen associated with?

Capsule

12

What is the O-antigen associated with?

LPS

13

What shape are Cocci?

Spherical-shaped

14

What shape are Bacilli?

Rod-shaped

15

What shape are Spirochetes?

Spiral-shaped

16

What are the five ways that bacteria can be classified?

1) Visible features
2) Nutrition
3) End products
4) Surface molecules
5) Nucleic acid analysis

17

What are the two major categories of bacteria?

Gram-positive & Gram-negative

18

What are the characteristics of gram-negative bacteria?

- Contain an additional outer membrane
- Thin peptidoglycan layer
- LPS +
- No sporulation
- Pink/ Red

19

What are the general characteristics of gram-positive bacteria?

- No outer membrane
- Thick peptidoglycan layer
- LPS negative
- Teichoic acid & Lipoteichoic acid positive
- Can form spores
- Purple

20

What are acid fast bacteria?

- Contain waxlike lipid coat of mycolic acid

21

Why is peptidoglycan a good drug target?

Essential for bacterial survival & unique to prokaryotes i.e. bacteria

22

List the steps of Gram stain & the colors associated with each step.

1) Crystal Violet stain, binds gram+ & turns them purple
2) Crystal Violet precipitated with iodine-->remains in + not -
3) Unbound stain removed with decolorizer
4) Safranin counter-stain applied, turns gram- red

23

Describe the structure of LPS. Where is LPS found?

LPS is found in the outer leaflet of the phospholipid bilayer in gram-negative bacteria. LPSconsists of:
- Lipid A
- Core polysaccharide
- O-antigen

24

What is Lipid A? Describe how Lipid A interacts with the immune system.

Lipid A is the innermost subunit of LPS that possesses it's endotoxin activity
- Binds CD14 of TLR4, leading to the production of pro-inflammatory cytokines
- Can induce septic shock

(Anchors LPS to the outer leaflet)

25

What is the Core protein?

Intermediate subunit of LPS between Lipid A & O-Antigen

26

What is O-Antigen?

Part of LPS that is used to classify gram-negative bacteria

27

What are Pili?

Also called fimbrae, are hair-like structures on gram-negative & positive bacteria

28

What is a common pili?

Hair-like structure involved in bacterial attachment to epithelial cells

29

What is a sex pili?

- Hair-like structures involved in the exchange of genetic material from on bacteria to another
- Encoded on F plasmid & referred to as F pili

30

What are flagella?

- Rotating helical structures attached to the plasma membrane & involved in locomotion
- Important virulence factor

31

What is a Capsule?

- Loose polysaccharide or protein layer surrounding some gram-positive or gram-negative bacteria
- Serves as another important virulence factor
- Antiphagocytic

32

Biolfim

Organized community of bacterial cells w/ capsule around the entire community

33

What does a positive Quelling test identify?

Bacterial capsulses

34

Why are patients' status post splenectomy more susceptible to infection by capsulated bacteria?

Capsulated bacteria are opsonized & cleared by the spleen

35

What type of bacteria can make endospores?

Gram-positive

36

What are tiechoic & lipotiechoic acid? What type of bacteria are they associated with, and what is their function?

Tiechoic & LTA= components of the thick peptidoglycan layer of gram+ bacteria
- Function= facilitate attachment of gram+ bacterial cells to host & other bacteria

37

What is mycolic acid?

Long, branched chain fatty acids that are covalently attached to peptidoglycan in "acid fast" bacteria

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