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Microbiology > Exam #1: Introduction > Flashcards

Exam #1: Introduction Flashcards

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Biology 101 flashcards
1
Q

Define Virulence.

A

Ability of a microorganism to cause disease

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2
Q

Define Virulence Factor.

A

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

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3
Q

What are the distinguishing features of viruses?

A
  • Smallest, 0.03-0.3 um–can be seen w/ EM only

- Obligate intracellular pathogens

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4
Q

What are the distinguishing features of bacteria?

A
  • 0.1-10 um
  • Simple
  • Unicellular
  • Prokaryote (lack membrane-bound organelles)
  • Reproduce by asexual division
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5
Q

What are the distinguishing features of fungi?

A
  • 4-10 um
  • More complex
  • Eukaryotic
  • Reproduce sexually & asexually
  • Unicellular or multiceullular
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6
Q

What are the distinguishing features of parasites?

A
  • 4um- many meters long (i.e. largest/ longest)

- Most complex microorganisms

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7
Q

What are the general features of prokaryotes?

A

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
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8
Q

What are the general features of eukaryotes?

A

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
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9
Q

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

A

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

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10
Q

What is the H-antigen associated with?

A

Flagella

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11
Q

What is the K-antigen associated with?

A

Capsule

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12
Q

What is the O-antigen associated with?

A

LPS

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13
Q

What shape are Cocci?

A

Spherical-shaped

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14
Q

What shape are Bacilli?

A

Rod-shaped

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15
Q

What shape are Spirochetes?

A

Spiral-shaped

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16
Q

What are the five ways that bacteria can be classified?

A

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

17
Q

What are the two major categories of bacteria?

A

Gram-positive & Gram-negative

18
Q

What are the characteristics of gram-negative bacteria?

A
  • Contain an additional outer membrane
  • Thin peptidoglycan layer
  • LPS +
  • No sporulation
  • Pink/ Red
19
Q

What are the general characteristics of gram-positive bacteria?

A
  • No outer membrane
  • Thick peptidoglycan layer
  • LPS negative
  • Teichoic acid & Lipoteichoic acid positive
  • Can form spores
  • Purple
20
Q

What are acid fast bacteria?

A
  • Contain waxlike lipid coat of mycolic acid
21
Q

Why is peptidoglycan a good drug target?

A

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

22
Q

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

A

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
Q

Describe the structure of LPS. Where is LPS found?

A

LPS is found in the outer leaflet of the phospholipid bilayer in gram-negative bacteria. LPSconsists of:

  • Lipid A
  • Core polysaccharide
  • O-antigen
24
Q

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

A

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
Q

What is the Core protein?

A

Intermediate subunit of LPS between Lipid A & O-Antigen

26
Q

What is O-Antigen?

A

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

27
Q

What are Pili?

A

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

28
Q

What is a common pili?

A

Hair-like structure involved in bacterial attachment to epithelial cells

29
Q

What is a sex pili?

A
  • 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
Q

What are flagella?

A
  • Rotating helical structures attached to the plasma membrane & involved in locomotion
  • Important virulence factor
31
Q

What is a Capsule?

A
  • Loose polysaccharide or protein layer surrounding some gram-positive or gram-negative bacteria
  • Serves as another important virulence factor
  • Antiphagocytic
32
Q

Biolfim

A

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

33
Q

What does a positive Quelling test identify?

A

Bacterial capsulses

34
Q

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

A

Capsulated bacteria are opsonized & cleared by the spleen

35
Q

What type of bacteria can make endospores?

A

Gram-positive

36
Q

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

A

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

37
Q

What is mycolic acid?

A

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

Microbiology (49 decks)

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