Intro to Med Micro

Question 1

Microbiology includes which four types of organisms?

Answer 1

1) bacteria
2) virus
3) fungi
4) parasites

Question 2

Approximately how many cells are in our body? And how many bacteria are in our body?

Answer 2

cells in body - 10^14 cells

bacteria in body - 10^15 cells

Question 3

Which is bigger, viruses or bacteria?

Answer 3

bacteria

Question 4

Which is bigger, bacteria or protozoa/fungi?

Answer 4

protozoa/ fungi

Question 5

Can you see viruses with light microscope?

Answer 5

No, electronic microscope is needed

Question 6

What is the smallest infectious particles?

Answer 6

viruses

Question 7

True or False. Bacteria are multicellular organisms

Answer 7

FALSE. they are unicellular

Question 8

If bacteria are prokaryotes, what about fungi and parasites?

Answer 8

fungi and parasites are both eukaryotes

Question 9

True or False. Fungi are ALL multicellular

Answer 9

False. yeast is unicellular

Question 10

Of the four categories of microorganisms, which is the smallest?

Answer 10

viruses

Question 11

Of the four categories of microorganisms, which is the most complex?

Answer 11

parasites

Question 12

Are parasites unicellular or multicellular?

Answer 12

both

Question 13

What is the difference between eukaryotes and prokaryotes in regards to presence of nucleus?

Answer 13

prokaryotes do not have nucleus (bacteria)

Question 14

True or False. Humans and bacteria utilize the same ribosomes?

Answer 14

False. bacteria use a smaller ribosome (70S)

Question 15

What structure is unique to bacteria?

Answer 15

peptidoglycan cell wall

Question 16

What are some ways to detect bacteria in clinical samples (5)?

Answer 16

1) microscopy
2) detection of bacterial antigens
3) detection of bacterial nucleic acids
4) culture - metabolic properties
5) detection of antibody response to bacteria (such as looking for IgM –> primary infection Abs)

Question 17

What are some ways to classify bacteria (5)?

Answer 17

1) visible features
2) nutrition
3) end products
4) surface molecules
5) nucleic acid

Question 18

What type of visible features are used to classify bacteria?

Answer 18

1) shape
2) spore formation
3) Gram reaction

Question 19

How is nutrition used to classify bacteria?

Answer 19

1) growth media
2) aerobic vs. anaerobic
3) temperature required for optimal growth

Question 20

What are you looking for when using end products to classify bacteria?

Answer 20

production of specific enzymes or toxins

Question 21

What are some surface molecules that can be used to classify bacteria?

Answer 21

unique proteins, sugars or lipids - usually cell surface

Question 22

What is a more rigid classification system currently being delineated?

Answer 22

nucleic acid analysis

Question 23

What shape do cocci have?

Answer 23

spherical

Question 24

What shape do bacilli have?

Answer 24

rod - straight or curved

Question 25

What shape do spirochetes have?

Answer 25

spirals

Question 26

True or False. Both Gram (+) and Gram (-) have peptidoglycan in their cell wall

Answer 26

True

Question 27

A bacteria is Gram (+), what color will it be?

Answer 27

purple

Question 28

A bacteria is Gram (-), what color will it be?

Answer 28

reddish, pink

Question 29

Is peptidoglycan located external or internal to the capsule?

Answer 29

internal

Question 30

Is peptidoglycan located external or internal to cytoplasmic membrane?

Answer 30

external

Question 31

What is the function of peptidoglycan in bacteria?

Answer 31

protection against physical/mechanical, osmotic, chemical and biological agents

Question 32

True or False. peptidoglycan determines shape

Answer 32

TRUE

Question 33

True or False. peptidoglycan makes for a good drug target

Answer 33

True, bc it's not in humans

Question 34

What are some proinflammatory effects of peptidoglycan?

Answer 34

1) fixes complement 2) binds to pattern recognition receptors (ex. toll-like receptors) 3) triggers TNF production (via NFk-B)

Question 35

Why do Gram (+) bacteria turn purple?

Answer 35

the crystal violet is trapped in a thick, cross-linked peptidoglycan layer

Question 36

What are two components of Gram (+) envelope?

Answer 36

1) peptidoglycan | 2) teichoic acid

Question 37

Lipoteichoic acid (LTA) is associated with which structure?

Answer 37

plasma membrane

Question 38

Teichoic acid is associated with which structure?

Answer 38

peptidoglycan

Question 39

What is the purpose of teichoic acid and LTA?

Answer 39

promote attachement to other bacteria and to host cells

Question 40

True or False. Teichoic acid and LTA are specific to Gram (+) bacteria only

Answer 40

True

Question 41

True or False. Teichoic acid and LTA are important virulence factors for Gram (+) bacteria

Answer 41

True

Question 42

Why do Gram (-) bacteria turn pink upon Gram staining?

Answer 42

they have a thin peptidoglycan layer and do not retain crystal violet thus they are counterstained with saffarin to turn reddish pink

Question 43

True or False. Both Gram (+) and Gram (-) bacteria have two membrane layers

Answer 43

False, only Gram (-) bacteria have two layers

Question 44

Gram (-) bacteria are surrounded by an outer membrane rich in _____ and _____

Answer 44

1) porins | 2) lipopolysaccharide (LPS)

Question 45

Where is peptidoglycan located in Gram (-) bacteria?

Answer 45

periplasmic space

Question 46

What is the function of outer membrane of Gram (-) bacteria?

Answer 46

maintains structure and permeability barrier (porins)

Question 47

Gram (-) bacteria have an asymmetric phospholipid bilayer, what is in its inner leaflet and what is in its outer leaflet?

Answer 47

inner --> phospholipids | outer --> lipopolysaccharide (LPS)

Question 48

What are the three components of LPS?

Answer 48

1) lipid A 2) core polysaccharide 3) O antigen

Question 49

Which component of LPS is responsible for endotoxin activity?

Answer 49

lipid A

Question 50

Which of the three components of LPS is required for bacterial structure and viability?

Answer 50

core polysaccharide

Question 51

What is a long, linear polysaccharide of repeating saccharide units of 4 to 7 sugars/unit?

Answer 51

O antigen

Question 52

How do LPS cause inflammation?

Answer 52

bind to CD14 and TLR4 on phagocytes/ APCs --> massive inflammatory response, causing inflammation and could cause septic shock

Question 53

Which cytokines are responsible for septic shock (3)?

Answer 53

1) TNF 2) IL-1 3) IL-6

Question 54

True or False. Acid-fast bacteria do not contain peptidoglycan

Answer 54

FALSE.

Question 55

What long, branched fatty acid is associated with acid-fast bacteria?

Answer 55

mycolic acids

Question 56

What is responsible for the thick waxy membranous layer of acid-fast bacteria?

Answer 56

mycolic acids

Question 57

What stain is used for acid-fast stain?

Answer 57

carbol fuchsin

Question 58

What is used in the decolorization step of acid-fast stain?

Answer 58

acid alcohol

Question 59

What is used to counter-stain in acid-fast stain?

Answer 59

methylene blue

Question 60

What's the function of mycolic acid?

Answer 60

impedes entry of chemicals/lysosomal enzymes which leads to a fastidous slow growing bacteria

Question 61

Structure of acid-fast bacteria is similar to Gram (+) or Gram (-) bacteria?

Answer 61

Gram (+)

Question 62

Do acid fast bacteria have an outer membrane?

Answer 62

No

Question 63

What are the three components of acid fast cell wall?

Answer 63

1) lipoarabinomannan (LAM) 2) arabiogalactans 3) mycolic acid

Question 64

Which of components of acid fast cell wall is functionally similar to LPS?

Answer 64

LAM

Question 65

Arabinogalactans are branched polysaccharides that bind to _____

Answer 65

mycolic acid

Question 66

What are molecular hair-like projections on surface of both Gram (+) and Gram (-) cells?

Answer 66

pili

Question 67

Pilin forms a tube with a small ____ core

Answer 67

hollow

Question 68

Pili/ fimbrae are composed of protein subunits called ____

Answer 68

pilin

Question 69

What are the two functional types of pili

Answer 69

1) common (somatic) | 2) sex

Question 70

Which type of pili is involved in attachment to epithelial cells

Answer 70

common

Question 71

What is also called adhesins, lectins, evasins and aggressins?

Answer 71

common pili

Question 72

Which type of pili is involved with gene transfer?

Answer 72

sex pili

Question 73

How many sex pili are usually present in each cell?

Answer 73

one

Question 74

What are rotating helical structures anchored to plasma membrane responsible for locomotion?

Answer 74

flagella

Question 75

What structure is H-antigen associated with?

Answer 75

flagella

Question 76

What structure is K-antigen associated with?

Answer 76

capsule

Question 77

Are H and K antigens important virulence factors?

Answer 77

you-betcha!

Question 78

What is also known as slime layer?

Answer 78

capsule

Question 79

What's the function of capsules?

Answer 79

aides in protection from immune system 1) poorly antigenic 2) antiphagocytic

Question 80

Are capsules important for culture? What about survival in host?

Answer 80

culture - not important | host survival - important

Question 81

What is an organized community of microbial cells that has a capsule/ slime layer over the entire population?

Answer 81

biofilm

Question 82

What reaction can be used to identify capsules?

Answer 82

Quellung reaction

Question 83

If capsules are present, what occurs when anti-capsular antibodies are added in Quellung reaction?

Answer 83

the capsules will swell

Question 84

How are encapsulated bacteria removed from body?

Answer 84

opsonized and cleared by spleen

Question 85

What can be used as an antigen in vaccines against encapsulated bacteria?

Answer 85

capsules + protein conjugate

Question 86

Which type of bacteria can become endospores: Gram (+) or Gram (-)?

Answer 86

``` some Gram (+) never Gram (-) ```

Question 87

Under what conditions are endospores formed?

Answer 87

harsh environments

Question 88

Bacteria convert from a vegetative state to a ____ state

Answer 88

dormant

Question 89

When does germination of endospores occur?

Answer 89

favorable environmental conditions

Question 90

True or False. An endospore gives rise to a single bacteria once the conditions become favorable

Answer 90

True

Question 91

Which of the following statements are true regarding endospores? 1) highly resistant to enviromental stressors 2) can exist for centuries 3) spores can be aerosolized

Answer 91

All 3 statements are true

Question 92

What kind of structure do endospores have?

Answer 92

dehydrated, multishelled

Question 93

What are the contents of an endospore (3)?

Answer 93

1) one complete copy of chromosome 2) minimum concentration of proteins and ribosomes 3) high concentration of calcium bound to dipicolinic acid

Question 94

Describe the inner membrane of endospores

Answer 94

2 peptidoglycan layers

Question 95

Describe the outer coat of endospores

Answer 95

keratin-like protein

Question 96

What sterilization technique must be done to rid of endospores?

Answer 96

autoclave, 120 degrees celsius at high pressure for >20 min

Question 97

Can endospores withstand attacks by enzymes and chemicals?

Answer 97

YEP

Question 98

A patient presents with a flulike illness (fever, chills, headache, cough, myalgias and chest pain). Analysis of a sputum sample by phase-contrast microscopy reveals intracellular spherical forms of about 8 µm diameter with a single nucleus. The causative agent of the infection is likely a ____

Answer 98

fungus