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Bacteriology (mine) > Intro to Bacteriology > Flashcards

Intro to Bacteriology Flashcards

1
Q

Where does protein synthesis occur in eukaryotes?

A

80s ribosomes

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2
Q

Describe the nucleoid structure of prokaryotes.

A

mass of genetic material with no membrane or envelope has supercoiled DNA and condensed with scaffold proteins

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3
Q

What is unique about transcription and translation of mRNA in bacteria?

A

they could occur simultaneously

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4
Q

How does gram staining with crystal violet works?

A

stains cytoplasmic elements

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5
Q

List the steps of gram staining.

A

1) crystal violet 2) gram’s iodine 3) decolorizer (alcohol/acetone) 4) safranin red

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6
Q

What’s the function of the gram’s iodine?

A

complexes with crystal violet and acts as mordant (chemical that fixes the dye)

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7
Q

What does the decolorizer does to the gram + bacteria?

A

(THICK peptidoglycan) - dye-iodine complex will NOT wash out - organism stays purple

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8
Q

What does the decolorizer does to the gram - bacteria?

A

(THIN peptidoglycan) - only crystal violent is washed out - become unstained

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9
Q

What’s the point of the safranin red stain?

A

a counterstain no effect on the gram + bacteria (already purple) makes the gram - bacteria pink bc it’s now unstained

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10
Q

What can antibiotics do to the shape/size of bacteria?

A

can change the original shape/size -> make cocci bacteria appear as rods

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11
Q

What stain can be used to penetrate the cell wall of bacteria (where gram staining doesn’t work)?

A

acid fast stain

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12
Q

What are the steps of acid fast stains?

A

1) stain with carbolfuchsin red
2) add decolorizer
3) add methylene blue

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13
Q

What does the decolorizer do to acid fast positive bacteria?

A

bacteria remains red - stain will not wash out

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14
Q

What does the decolorizer do to acid fast negative bacteria?

A

become colorless

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15
Q

Which bacteria will be stained blue with methylene blue counterstain?

A

non-acid fast bacteria

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16
Q

What determines if a bacteria will have a capsule or not?

A

growth conditions (microenvironment) bc capsules take a lot of energy to produce

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17
Q

How does a capsule protect against innate defense mechanisms?

A

1) complement binds capsule and forms MAC
2) make is ineffective against capsule because pore does not penetrate deep enough to reach cytoplasm

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18
Q

How do capsules prevent phagocytosis?

A

makes the bacteria very “sticky” so phagocytic cells have hard time adhering

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19
Q

What are capsules made of?

A

high MW polysaccharide or peptide

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20
Q

What are the components of the gram positive envelope?

A

1) THICK peptidoglycan layer on outside of PM
2) teichoic and lipoteichoic acids intewovened in the peptidoglycan - helps give strength and stability (lipo anchors peptidoglycan to PM)
3) periplasmic space
4) various transmembrane proteins in plasma membrane

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21
Q

What occurs in the periplasmic space?

A

located in between the outer peptidoglycan layer and PM - where synthesis of peptidoglycan occurs

(more impt and larger in gram - bacteria)

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22
Q

What makes up peptidoglycan?

A

N-acetylglucosamine crosslinked by peptidoglycan interbridges to N-acetylmuramic acid

the different layers are connected by peptide chains forming an infrastructure that resembles chain-linked fence

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23
Q

What’s the function of peptidoglycan?

A

unique to bacteria (great target for antibiotics)

give bacteria strength, integrity and shape - acts as cytoskeleton

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24
Q

What makes up the gram (-) cell envelope?

A

THIN peptidoglycan layer within periplasmic space

Outermost layer is outer phospholipid membrane with lipopolysaccharides embedded (some drugs that work on gram (+) will not work on gram negative simply bc it posses this outer phospholipid membrane)

inner plasma membrane contains its own set of proteins

porins transversing the outer membrane

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25
Q

What’s the function of the proteins on the inner plasma membrane?

A

used for intracellular processes such as respiration and oxidative phosphorylation (since it does not have mitochondria)

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26
Q

What’s significant about the periplasmic space for gram (-) bacteria?

A

contains enzymes that destroy antibiotics before they penetrate the inner plasma membrane and reach the cytosol

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27
Q

What’s another name for lipopolysaccharide (LPS)?

A

lipoglycan and endotoxin

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28
Q

What’s the importance of LPS?

A

binds the CD14 receptor in immune cells and initiates secretion of cytokines

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29
Q

What’s the importance of Lipid A?

A

the endotoxin of LPS - illicits the immune response/cytokine release via binding to CD14

(hydrophobic segment that sits in the membrane)

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30
Q

What’s the role of porins?

A

gatekeepers of the cell - can actively pump antibiotics

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31
Q

What are exotoxins?

A

damaging toxins that are secreted by bacteria

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32
Q

What are the O side chains of LPS?

A

the carbohydrates that the body sees and makes Ab against

used in bacterial serotyping

can bind to Mg or Ca to add some structural integrity to the cell and prevent some antibiotics from working

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33
Q

Where are many of the proteins and enzymes needed for bacteria metabolism?

A

embedded within the cell membrane

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34
Q

List some examples of proteins on the cell membrane.

A
  1. transporters
  2. anabolic enzymes
  3. enzymes that generate ATP (cytochrome oxidase system)
  4. cell motility (flagella and pili)
  5. mediation of chromosomal segregation
  6. molecular sensors (drive bacterial movement towards/away favorable/hostile environments)
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35
Q

What are pili composed of?

A

pilin

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36
Q

What’s the function of common pili?

A

(fimbrae or type IV)

mediates attachment of bacterial cell to host cells or any surface

it also inhibits phagocytosis!

The pili are antigenic

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37
Q

What’s the function of sex pili?

A

used for exchange of genetic material, conjugation

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38
Q

What are inclusion bodies?

A

storage granules where bacteria hoard excess nutrients and minerals

may look like clearing inside the cell

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39
Q

What are nucleoids?

A

highly coiled bacterial chromosomes intermixed with RNA, polyamines, and support (scaffold) proteins - DO NOT have outer membrane

some drugs can inhibit supercoiling making the genome very lose and disorganized

40
Q

What is kept safe within a spore?

A

genetic material!

41
Q

What makes up flagella?

A

rotary motor, hook, and propeller (flagellin - highly antigenic)

42
Q

What happens when you turn off the gears of the flagella?

A

tumbles in place until the gears are turned back on to propel it somewhere

43
Q

How do bacteria bring in the nutrients they need?

A

simple diffusion, facilitated diffusion, active transport

44
Q

Why is it bad to have free iron floating around in our body?

A

bacteria can uptake the iron through active transport and use it as a source of fuel!

45
Q

How do bacteria use sideophores?

A

a strong iron-binding agent that will strip the iron from our body’s cells to be used for bacterial functions

46
Q

What are the 3 main pathways where percursor metabolites are produced and consumed?

A
  1. Emden-Myerhof-Parnas (EMP) Pathway (aka glycolytic or anaerobic pathway)
  2. Tricarboxylica acid cycle (TCA)
  3. Pentose phosphate pathway
47
Q

What are fastidious organisms?

A

pathogens that can no longer make a nutrient required for life and depends on human metabolism to make that nutrient

48
Q

What determines the production efficiencies of bacteria’s precursor metabolites?

A

growth conditions and nutrient availability

49
Q

What pathways produce high energy phosphate bonds?

A

TCA and EMP pathways (ADP->ATP)

50
Q

What is the initial substrate of substrate level phosphorylation?

A

pyruvate (O2 is not required!)

51
Q

What are the end products of substrate level phosphorylation?

A

organic acids, alcohols, CO2 and hydrogen

(the different end products can be used to ID the bacteria!)

52
Q

What type of metabolism does pyruvate undergo for us to get the endproducts?

A

fermentative metabolism

53
Q

How are enterotubes used to ID bacteria?

A

1) innoculate the compartments with different colonies of bacteria and test for one of the metabolic end products
2) compare the product to a color chart to ID

54
Q

How is selective media used?

A

used for growing a single or handful of species from a specimen of thousands of species (allows the growth of some bacteria while inhibitting the growth of others)

55
Q

How is differential media used?

A

used for differentiating closely related organisms or groups of organisms by using certain dyes or chemicals to produce characteristic growth patterns

56
Q

What could be used to ID bacteria that cannot be grown in culture?

A

sequencing 16S ribosomal RNA (molecular fingerprint)

57
Q

What pathway is shared by us and bacteria?

A

oxidative phosphorylation! (both anaerobic and aerobic forms)

so cannot manipulate this pathway in antibiotics bc it will be toxic to us as well

58
Q

What enzymes do aerobics have to detoxify molecular oxygen?

A

catalase and superoxide dismutase

59
Q

What is a facultative aerobe?

A

can use O2 if present, but can also survive on anaerobic metabolism

60
Q

What’s microaerophilic?

A

not true anaerobe - grows best at low O2

61
Q

What was the first antibiotic?

A

protonsil

62
Q

Explain the magic bullet theory.

A

there were chemicals that you could put in the body that would only target microorganisms causing disease and not the host

63
Q

How does protonsil work?

A

sulfa drug (a pro-drug) that blocks the synthesis of folic acid (bacteria have to synthesize their own folic acids while human hosts obtain theirs from diet)

64
Q

What’s trimethoprim?

A

another drug that interferes with folate metabolism by inhibiting bacterial dihydrofolate reductase (DHFR)

65
Q

How do bacteria get the proteins generated inside the cytoplasm to the outside of the cell?

A

they have docking ports for chaperone proteins embedded in the membrane that direct proteins to exporters outside of the bacteria and into environment

66
Q

What’s the significance of protein secretion in gram (-) bacteria?

A

must secrete past 2 cell membranes (secretion channels types I-IV)

67
Q

What’s important about the type III secretion system?

A

used for virulence

“needle and syringe” for inserting proteins into eukaryotic cells

68
Q

What are the key enzymes used to unwind tightly coiled DNA?

A

DNA gyrase and topoisomerase

69
Q

How do chromosomes stick to cytoplasmic membrane at specific sites during replication?

A

since no mitotic spindles, make use of mesosomes

70
Q

Define F plasmids.

A

chromosomal exchange between bacteria (essential for replicating plasmid and transferring from one to another)

F= fertility; encodes the info for making sex pili (made by males)

71
Q

Define R plasmids.

A

R= resistance

carry genes encoding antibiotic resistance

72
Q

Define Virulence plasmids.

A

carry genes encoding toxis or other virulence factors

73
Q

What’s the genome of a bacteriophage?

A

RNA or DNA

74
Q

What’s significant about the virulence factors of bacteriophages?

A

can encode virulence factors that bacteria can use - staph enterotoxins or diptheria toxin

some pathogens actually need to be infected with the phage to become virulent

75
Q

What is transduction?

A

with the use of bacteriophages, allows the exchanging of DNA info between different bacteria

consist of a lytic and lysogenic cycle

76
Q

Define the lytic cycle.

A

Phage gets into the cell using the cells machinery. Phage leaves the cell by lysing

77
Q

Define the lysogenic cycle.

A
  1. Some of the phage DNA gets incorporated in the host genome.
  2. In order to replicate, the phage DNA has to pop out of the bacterial chromosome - this process causes some of the phage DNA to be swapped with some of the bacterial DNA when - forming hybrid phage
78
Q

How does transduction occur?

A

when the hybrid phage (phage DNA + bacterial DNA) move to infect a new bacterial host after lysis, it transfers DNA between bacteria

79
Q

What are restriction enzymes?

A

function like “bacterial immune system” against phage DNA (chops up the foreign DNA) - destroys whatever can potentially kill the bacteria

80
Q

What makes transformation different from transduction?

A

bacteria takes up free floating DNA fragments (no need for phages!)

81
Q

Where do the free floating fragments of DNA come from?

A

bacteria that die release their DNA into environment to either be degraded or transformed into other bacteria

82
Q

What happens during conjugation?

A

two microbes physically meet and one extends its sex pili to another recipient cell allowing for tranfer of genetic material

83
Q

What are transposons?

A

jumping genes - piece of genetic material that pops out and either re-inserts on same chromosome or another chromosome during transposition

can be transferred in plasmids during the process of conjugation

84
Q

What are pathogenicity islands?

A

compressed pieces of genome with all the virulence factors in one location - EVERYTHING the bacteria need to be pathogenic is in one place

85
Q

How do pathogenicity islands make a nonvirulent bacteria virulent?

A

the islands can mobilize and transfer all the virulent factors (toxins and proteins) from one organism to another by conjugation, transformation, or transduction

86
Q

What does a perfect life cycle of bacteria look like?

A

lag phase: bacteria gathering up enzymes

log phase: metabolic peak; replication occurs exponentially

stationary phase: rate of growth = rate of death; runs out of gas

death phase: bacterial decline due to exhaust of nutrients and accumulation of wastes

87
Q

What apparatus is used to grow bacteria?

A

chemostat - keeps bacteria in log phase

88
Q

Explain bacteria metabolic parsimony.

A

bacteria expend energy only if they have to - way for bacteria to adapt

89
Q

Define sterilization.

A

kills ALL microbial forms - including spores

done so with autoclaving and dry heat

90
Q

How does autoclaving work?

A

121OC, 15 psi, 20 min

kills by denaturation of proteins and nucleic acids - disrupts membranes - utilizing steam under pressure to kill

91
Q

How does dry heat work?

A

2 hr at 160OC

kills same as steam

92
Q

What are two other methods of sterilization?

A

1) UV or ionizing radiation (gamma rays): damages nucleic acids; used on US mails and tissues for transplant
2) gas vapors (chemical autoclaves): ethylene oxide or formaldehyde vapors; work by alkylating agents - used on anything that can withstand heat

93
Q

What’s disinfection?

A

most microbial forms are destroyed; spores and other resistant forms endure

it only reduces the microbial burden on the surface

environmental conditions affect effectiveness - soil and dirt blocks the effectiveness of the bleach (chloride compounds - oxidize sulfhydryl groups) and lysol (phenolic compounds- denature proteins) (does not do well with living cells)

94
Q

What should be used on living cells?

A

antispesis

95
Q

Define antisepsis.

A

microbes are inhibitted or eliminated in or on living tissue

no sporocidal activity implied

ethyl or isopropyl alchols denature proteins

iodophors (providone iodine) also denature proteins - betadine

Bacteriology (mine) (6 decks)

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