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Practice topics Exam 1 > Bacteria 1 > Flashcards

Bacteria 1 Flashcards

1
Q

Prokaryotes - lack

A

nucleus, membrane bound organelles

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2
Q

Prokaryotes - typically have ___ chromosome

A

single, double stranded circular DNA chromosome

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3
Q

Prokaryotes - ribosome

A

smaller! important because we are able to target this

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4
Q

Prokaryotes - cell wall

A

mesh like

comprised of peptidoglycan

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5
Q

Detection of bacteria in clinical samples - microscopy

A

Morphology

Gram stain

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6
Q

Detection of bacteria in clinical samples - detection of bacterial antigens

A

H antigen
K antigen
O antigen (LPS)
capsule

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7
Q

Detection of bacteria in clinical samples - Detection of bacterial nucleic acid

A

PCR

Sequencing

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8
Q

Detection of bacteria in clinical samples - Culture

A

Metabolic properties

Biomechanical tests

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9
Q

Detection of bacteria in clinical samples - Detection of antibody response to bacteria

A

ELISA
Western blot
Immunostaining

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10
Q

Taxonomy/Classification

A

Binomial according to Linnean scheme (genus species)
According to fundamental features
By nucleic acid analysis

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11
Q

Taxonomy/Classification - according to fundamental features like what

A

Visible features - shape, spore formation, gram rx
Nutrition - aerobic vs. anaerobic, growth temp
End products - production of enzymes or toxins
Surface molecules - unique proteins, sugars, or lipids

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12
Q

Bacterial shapes - Cocci

A 
Circular 
Coccus = just one
Diplococci = two circles 
Streptococci = single strand of circles
Staphylococci = pyramid, grape shape (cluster)
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13
Q

Bacterial shapes - Bacilli

A 
Coccobacillus = oval
Bacillus = longer than it is wide
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14
Q

Cytoplasm consists of

A

Chromosome, mRNA, ribosomes, proteins and metabolites

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15
Q

Cytoplasmic membrane is a __ layer

A

lipid

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16
Q

Cytoplasmic membrane is responsible for

A

Electron transport, energy production

many of the functions attributable to organelles in eukaryotes

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17
Q

Cell wall =

A

peptidoglycan

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18
Q

Appendages =

A

pili (used for attachment to surfaces)

flagella (movement)

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19
Q

Cell wall - classifications

A

Two major classifications of bacteria
Gram positive cell wall
Gram negative cell wall

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20
Q

Gram positive cell wall

A

Thick peptidoglycan layer

Single inner plasma membrane

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21
Q

Gram negative cell wall

A 
Outer membrane 
Peptidoglycan
Periplasmic space
Inner plasma membrane 
Two membranes!
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22
Q

Gram stain - positive

A

Step 1 - crystal violet
Step 2 - gram iodine
Step 3 - decolorizer (alcohol or acetone)
Step 4 - safranin red
With gram positive it will act right away with the peptidoglycan and when you decolorize it does not come out, so color remains the violet

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23
Q

Gram stain - negative

A

Step 1 - crystal violet
Step 2 - gram iodine
Step 3 - decolorizer (alcohol or acetone)
Step 4 - safranin red
With gram negative the outer membrane excludes the stain from getting to the peptidoglycan so after you decolorize it gets rid of the violet and when you use the red, the color becomes red

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24
Q

Peptidoglycan layer functions to provide

A 
Protection - physical, mechanical, osmotic, chemical and biological agents 
Determines cell shape
Gram stain (pos vs. neg)
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25
Q

Peptidoglycan is found uniquely on

A

BACTERIA
DRUG TARGET!
Will attack the bacteria and not the person

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26
Q

Peptidoglycan layer is made of what

A

Linear chain of alternating sugars cross linked by peptide chains

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27
Q

What is a big drug target

A

Peptidoglycan synthesis!
Drugs target because the bacteria cell continues to grow, but the peptidoglycan can’t grow so then the bacteria will eventually burst apart

28
Q

Ex of drugs that target peptidoglycan synthesis

A

Bacitracin
Cycloserine
Vancomysin

29
Q

Gram positive envelope - major components

A

Petidoglycan

Teichoic acid

30
Q

Gram positive envelope - major components - peptidoglycan

A

Many layers in gram pos (thick)
Extensive crosslinking
Peptidoglycan cen be degraded by treatment with lysozyme (found in tears and mucous)

31
Q

Gram positive envelope - major components - teichoic acid

A

PG associated
PM associated - lipoteichoic acid
Teichoic acid is only in gram pos!

32
Q

Gram negative envelope - major components

A

one layer of peptidoglycan (PG)

PG is in the space between inner and outer membrane (the periplasmic space)

33
Q

Gram negative outer membrane

A

Permeability barrier
Risk of porins - allow diffusion of small hydrophlic molecules
Asymmetric phospholipid bilayer - inner leaflet contains phospholipids, outer leaflet has unique molecule called lipopolysaccharide (LPS)

34
Q

Gram negative outer membrane - lipopolysaccharide (LPS) endotoxin

A

Potent activator of the immune system
Causes inflammation and can cause septic shock
Major component of the Gram neg outer membrane

35
Q

Gram negative outer membrane - lipopolysaccharide (LPS) endotoxin - Comprised of

A

3 subunits
Lipid A!!! (main particle of polysaccharide)
Core polysaccharide
O antigen

36
Q

Bacteria with unique cell wall composition - cell wall with less bacteria

A

Mycoplasma

37
Q

Bacteria with unique cell wall composition - Acid fast bacteria

A

Mycobacteria, Nocardia, Corynebacterim…
Complex cell envelope
Mycolic acids
High glycolipid content in envelope
Thick waxy membranous layer outside the peptidoglycan
Only one membrane

38
Q

Bacteria with unique cell wall composition - acid fast stain

A

Stained red by carbol fuchsin
Acid alcohol destain
Methylene blue use to counter stain and label other bacteria
Acid fast will be red because the alcohol does not destain it

39
Q

Appendages - Pili/Fimbrae

A

Proteinaceous hair-like projections (on surface of gram pos and neg cells)
Multiple types of pili (dynamic or static)
Function depends on type - Conjunction (exchange of DNA), Motility, Attachment!

40
Q

Appendages - Flagella

A

Rotating helical structures anchored to PM responsible for motility!

41
Q

Appendages - flagella - basic arrangement on cell

A

can be at one pole - polar/mono
can be more than one at a single pole - lopho
can be at both poles - amphi
can be all around the bacteria - peri

42
Q

Appendages - flagella - are driven by

A

membrane potential

43
Q

Capsule (glycocalyx/K antigen)

A 
Loose polysaccharide (or protein) layer surrounding some gram pos or neg bacteria 
Hydrophilic - made of single or multiple sugar residues
44
Q

Capsule (glycocalyx/K antigen) - aids in what

A

protection from the immune system

  • poorly antigenic
  • antiphagocytic
  • major virulence factor
45
Q

Endospores - occur with

A

some gram pos bacteria under harsh environmental conditions

46
Q

Endospores - bacteria do what

A

convert from a vegetative state (active and multiplying) to a dormant state

47
Q

Endospores - gives rise to

A

a single bacteria when environmental conditions are favorable (germination)

48
Q

Endospore - localization

A

Localization of the spore within a cell is characteristic of the bacteria and can assist in identification

49
Q

Endospores can withstand

A

extreme pH, temp, radiation, attack by enzymes and chemicals

50
Q

Endospores - structure

A

dehydrated, multishelled structure
contains complete copy of the chromosome
contains min concentration of proteins and ribosomes

51
Q

Endospores - implications

A

Can be aersolized
Can be found in a wide variety of environments over an extended period of time
Care must be taken to sterilize surfaces (doesnt always kill spores)
Can exist for centuries

52
Q

Metabolism - requirements for growth

A

Energy source

Raw materials to build proteins, structures and membranes

53
Q

Metabolism - minimum requirements for growth

A

source of carbon and nitrogen, an energy source (like sugar), water and various ions (most need iron)

54
Q

Typical growth curve under optimal growth conditions

A

Lag phase
Exponential phase (can double numbers in 18 min)
Stationary phase (run out of nutrients)
Decline

55
Q

Growth and metabolism - bacteria multiply by

A

binary fission and growth in culture is determined by multiple factors

  • pH optimum
  • Aerobic vs. Anaerobic
  • Nutrients/Composition of media
  • Temperature
56
Q

Growth and metabolism - rule of thumb is that in rich media

A

bacteria divide every 20 minutes at 37C but range can be up to 20 hours

57
Q

Bacterial can be divided into groups based on metabolic properties -

A

how the organism deals with oxygen

what the organism uses as a carbon and energy source

58
Q

Bacterial can be divided into groups based on metabolic properties - Aerobic

A

Utilizes respiration to meet its energy need

59
Q

Bacterial can be divided into groups based on metabolic properties - Anaerobic

A

Utilizes fermentation to meet its energy needs

60
Q

Bacterial can be divided into groups based on metabolic properties - Aerobic vs. Anaerobic

A

Aerobes require O2 to live

Anaerobes are killed by it

61
Q

Bacterial can be divided into groups based on metabolic properties - Facultative

A

Can respire or ferment

62
Q

Bacterial can be divided into groups based on metabolic properties - Obligate/Strict

A

Obligate aerobe - cannot live without O2

Obligate anaerobe - cannot live in presence of O2

63
Q

Bacterial can be divided into groups based on metabolic properties - Micoaerophilic

A

Grow best at low O2

64
Q

Bacterial genetics - bacteria are

A

haploid (one copy of the chromosome)

65
Q

Bacterial genetics - genes associated with pathogenesis are often organized in

A

large clusters, called pathogenicity islands
Blocks of genes groups on the chromosome
Fundamentally different from the rest of the genome (GC content)

66
Q

Reproduction

A

Binary Fission
An exact copy of the genome is made
A single cell divides into 2 (binary) daughter cells

67
Q

Gene Transfer - modes

A

Transformation (lysis and then neighboring picks up)
Transduction (phage infects recipient cell)
Conjugation(bacterial sex)
Transposition

Practice topics Exam 1 (15 decks)

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