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Microbiology Final > Exam 1 materials > Flashcards

Exam 1 materials Flashcards

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1
Q

What are the three ways that bacteria can swap genes?

A
  1. Conjugation–via adjacent bacterium and pilus
  2. Transformation (first method that was discovered)—> bacteria can take up naked DNA from the environment.
  3. Transduction—> involves a virus (viruses are called phages when they attack bacteria); this is how the virulent strain of E. Coli got its genes
    resistance genes
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2
Q

What does a spore contain?

A

A chromosome, proteins, ribosomes and calcium bound to dipicolinic acid (resistant to heat and oxidation).
Spores also have a thick keratin coat around it.

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3
Q

What is packaged around bacterial genomes? Does this replace the histone we have in our DNA?

A

Bacteria have polyamides like specimens.

These are INSTEAD of histones-so they do not have histones.

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4
Q

What types of operons exist?

A

Repressible and inducible.

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5
Q

What type of operon is a lac operon? What needs to bind to it?

A

They are inducible.
The inducer is allolactose–it binds to and removes the repressor.
Sigma factors them bind to the promoter and allow the polymerase to bind, leading to transcription and translation of genes.

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6
Q

Where do you calculate the cell number on a typical bacterial growth curve?

A

During exponential phase (in the middle of it).

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7
Q

What are plasmids?

A

Small, self-replicating pieces of DNA that code for non-essential proteins and for the F-factor (fertility factor).

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8
Q

What are transposons?

A

Jumping genes.

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9
Q

Does oxidation produce or reduce energy?

A

Oxidation loses electrons–it PRODUCES energy as a result.

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10
Q

What are three types of phosphorylation reactions that generate ATP?

A
  1. Substrate level phosphorylation–glycolysis
  2. Oxidative phosphorylation–electron transport chain
  3. Photophosphorylation–use of light trapping pigment (e.g. chlorophyll)
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11
Q

What are the main ways that microbes produce energy?

A

Two general processes: respiration and fermentation. Both usually start with glycolysis but follow different subsequent pathways.

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12
Q

What is the Pentose Phosphate Pathway? What is its value besides the relatively small energy produced?

A
  • ->It is the most common GLUCOSE ALTERNATIVE pathway (also called the hexose monophosphate shunt)
    1. It operates simultaneous with glycolysis
    2. Allows for the breakdown of pentose (1ATP/cycle)
    3. Value: Produces important intermediate pentoses used to synthesize nucleic acids, glucose from carbon dioxide in photosynthesis, and some amino acids.
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13
Q

What is the Entner-Dodouroff Pathway? How much energy is produced per glucose?

A

It runs without glycolysis (vs. Pentose Phosphate Pathway which runs with glycolysis.
Per glucose, it makes 2NADPH and 1 ATP
Pseudomonas do this.

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14
Q

What are the end products of the Kreb’s Cycle per 2 acetyl CoA (1 original glucose)?

A 
4CO2
6NADH
2FADH2
2FADH2
2ATP

Remember–all multiples of two–two of everything except CO2 (4) and NADH (6)

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15
Q

What is the chemiosmotic model for ATP generation?

A

In chemiosmosis, the energy released when protons move along a gradient is used for ATP.
34 ATP released from each glucose

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16
Q

Contrast anaerobic respiration vs. fermentation.

A

For anaerobic respiratin, the final electron acceptor is an inorganic substance (vs. O2 as the final one for aerobic); some examples include nitrate and sulfate; high energy products are produced.

For fermentation, it does not required oxygen (although it may occur in its presence); does not require Kreb’s cycle/ETC, uses an organic molecule as final electron acceptor, and produces small amounts of ATP.

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17
Q

What is the overall goal of fermentation?

A

To supply NAD for glycolysis (small ATP from fermentation and glycolysis keeps organisms going)

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18
Q

What are the end products of fermentation? Why are they useful with bacteria identification?

A

The end products are diverse, so it helps with identification.

  1. Lactic Acid fermentation–the two pyruvic acids are reduced by two NADH to form lactic acid.
  2. Alcohol fermentation–pyruvic acid from glycolysis converted to acetaldehyde and 2 CO2; then the acetaldehyde is reduced by two NADH to form two molecules of ethanol.
  3. Heterolactic/heterofermentive–organisms that produce lactic acid ads well as other things.
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19
Q

What are the end products of lipid and protein catabolism?

A

Lipids-fatty acids and glycerol; then they are oxidized via the Kreb’s cycle.

Proteins–they are first reanimated and then enter the Krebs; they are also decarboxylated and dehydrogenated.

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20
Q

If you wanted to ID Salmonella vs. E.Coli, what type of biochemical test would you use?

A

You would use a biochemical tests that detects amino acid catabolizing enzymes involved in decarboxylation and dehydrogenation.
Salmonella produce hydrogen sulfide (H2S) when they remove sulfur from amino acids.

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21
Q

In addition to the hydrogen sulfide test, what other biochemical tests can you use to ID bacteria in a lab?

A
  • Fermentation test with Durham tubes–ID species AND/or strain too
  • Look at the ETCs as not all ETCs the same:
    1. Oxidase test for confirmation–Neisseria gonorrhoeae is positive
    2. Oxidased test for various gram negative rods (e.g. Pseudomonas is oxidase positive, Escherichia is negative.
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22
Q

What does the oxidase test to and what groups of bacteria are generally positive?

A

It looks at the ETCs of bacteria

Gram negative RODS are generally positive.

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23
Q

What is an autotroph vs. heterotroph vs. Phototroph vs. Chemotroph?

A

autotroph–do not need organic carbon source–they get it from CO2
heterotroph–need organic carbon from nutrition
Phototroph–light as source of energy
Chemotroph–no photosynthesis for energy

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24
Q

What is a photoautotroph vs. photoheterotroph vs. chemoautotroph?

A

photoautotroph–energy is light source; they get their organic compounds from CO2–plants
photoheterotroph–light as energy, they get their carbon from organic compounds–green and purple non-S bacteria
chemoautotroph-get energy from reduced inorganic compounds; use CO2 as principle source of carbon (Archeae)
Chemoheterotrophs–glucose for energy; glucose for carbon

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25
Q

What is an amphibolic pathway?

A

Metabolic pathways that function in anabolism and catabolism.

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26
Q

What are the main strategies that public health officials employ when dealing with risks to a population

A

Determine whether there is a reservoir; whether there is a factor; and if there is a vaccine, who should be vaccinated.

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27
Q

Prevalence vs. Incidence

A

Prevalence is percent or proportion of pop at one point in time (lots of Ps in prevalence)

Incidence is the number of new cases over time, often per year. Reported on a population basis, often per 100,000 people.

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28
Q

Mortality vs. Morbidity vs. Comorbidity

A

Mortality-number of deaths in a population
Morbidity–incidence in the population
Comorbidity-other diseases in the same patient

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29
Q

Endemic vs. epidemic vs. pandemic

A

Endemic–always present in the population; low morbidity or death rate
Epidemic–infect high numbers in a localized area, technically greater than expected numbers
Pandemic–spread to multiple continents

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30
Q

Virulence, pathogenicity and infectiousness

A

Virulence–ability of an organisms to cause disease; may be used to describe case fatality
Pathogenicitiy–likelihood that an infected person will show clinical symptoms
Infectiousness–number of exposed patients who become ill

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31
Q

Which two diseases that we learned ONLY have a human reservoir?

A

Small pox and polio

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32
Q

Give an example of a disease with an animal reservoir

A

Plague carried by rodents

33
Q

Give an example of inanimate reservoirs

A

Soil; tetanus from Clostridium tetani

34
Q

What is a reservoir?

A

The animate or inanimate sources of a disease

35
Q

What reservoir is the easiest to control?

A

With vaccination, easier to control diseases with human reservoirs; it’s harder to control animal reservoirs (although we can limit exposure to animals); diseases with inanimate reservoirs like water and soil are the hardest to control

36
Q

What are the five stages of infectious disease?

A

If you got sick, you’d have to hang out with your iPad version c before you get better (IPADC).

Incubation period – asymptomatic
Prodromal period – first symptoms appear
Acute period – invasion or illness
Decline period – illness is declining
Convalescent period– back to health
37
Q

Describe primary prevention, secondary prevention and tertiary prevention.

A

Primary prevention - prevent exposure
Secondary prevention- screen and treat during incubation period
Tertiary prevention– during symptoms – arrest, slow or reverse disease

38
Q

What role do vectors play in infectious disease? List several examples of vector-transmitted diseases.

A

A vector is something that transmits disease

A tick is the vector for Lyme disease (Borrelia burgdorferi)– the reservoir is the deer mouse
A tick is the vector for Rocky Mountain Spotted Fever (Rickettsia rickettsi)
A flea is the vector for the plague (Yersinia pestis)
A mosquito is the vector for West Nile

39
Q

What are carriers?

A

Carrier- person who is infected yet has no symptoms

Hep A carriers often in the news; Typhoid Mary is a historical example of a carrier

40
Q

What is the difference between direct host to host transmission and indirect host to host transmission?

A

Host to host transmission – I catch it directly from you (or the air) – respiratory viruses, STD’s, skin pathogens
Indirect host to host transmission – need a vector

41
Q

The acronym “BEINGS” describes the major categories of risk factors for disease. List these risk factor.

A

Behavioral, Environmental, Immunological factors, Nutritional Status, Genetic factors, Services, Social and Spiritual

42
Q

What are the areas in our body that should be free of microbes?

A

Blood, brain, organs, bladder

43
Q

Give four examples of flora normally found on our skin.

A

Staphylococcus epidermidis, Staphylococcus aureus, Clostridium perfringens, Propionibacterium acnes

44
Q

Describe the flora of the eye and the defenses found there.

A

Tears flush and contain enzymes like lysozyme
Minimal flora – Staphylococcus
Trouble makers - conjunctivitis - Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus

45
Q

Describe the flora and defenses in the respiratory tract.

A

Mucous and movement by ciliary escalator
Lactoferrin, lysozyme, sIgA
Alveolar macrophages
The lower you go, the less flora
Trouble makers - Streptococcus pyogenes, Staphylococcus aureus – nasal passages, Haemophilis influenzae – opportunistic many infections

46
Q

What bacteria can cause meningitis in the brain?

A

Bacterial meningitis - Neisseria meningitidis (meningococcal meningitis), and Haemophilis influenzae

47
Q

What are some components of an operon?

A

sigma factors and cAMP/CAMP

48
Q

What is virulence?

A

Virulence – the ability of a bug to cause disease

49
Q

What is LD50? vs. ID50?

A

LD50- the number of cells needed to kill half of the animals in a test group

  • a measure of death; a lethal dose for 50% (the “inoculum size”); we don’t do this for humans; how many organisms we need to ingest to get sick
    vs. ID50—> the “infectious” dose; can vary based on whether someone is immunodepressed, etc.
50
Q

What is attenuation?

A

Attenuation- weakening an organism – passage in culture, heat, chemical treatment
-weakening; you are actually getting the organism but weakened somehow; BCG (vaccination for mycobacteria/tuberculosis), other vaccines too

51
Q

Describe several virulence factors as they relate to adherence, invasion, and colonization.

A

Adherence- fimbria, pili, glycocalyx, adhesions

     - pili—can be used for sticking but also gene transfer
     - glycocalyx—sugar coating, more sticking--> increased virulence
     - adhesions—specific molecules that can bind to host cell receptors

Invasion- hyaluronidase, collagenase, fibrinolysin
-every bug, to become virulent, needs a “portal of entry”
-some bacteria have enzymes to break down our barriers; this will make them more virulent
-hyaluronidase-enzyme to break down hyaluronic acid—makes tissue more permeable and then can become more invasive (also cancers that metasticize have hyaluronidase)
-collagenase—can break down our collagen
-fibrinolysin—break down blood clots
(remember the exozymes)

Colonization– biofilms, resistance to host defenses—there various ways bacteria have adapted to grow and survive within us

- more protected from host defense when they form a biofilm; hard to get rid of biofilms, even with antibiotics
- they also colonize because they become resistant to host defenses (they do that in different ways)
52
Q

Describe the difference between exotoxin, endotoxin and enterotoxin.

A

Exotoxins- are secreted - cytolytic toxins, hemolysins, A-toxins, superantigens
-bacteria secrete toxins outside that work on our tissues and break down
-hemolysins—break down RBCs
-AB toxins: B part of toxin binds to HOST cell; then A goes into the cell and INTERFERES WITH TRANSLATION
Endotoxins– part of bacteria – LPS in Gram negative bacteria, for example
-part of the bacteria itself; not excreted; part of bug; not secreted; gram negative cell wall?

Enterotoxin- effects the intestinal mucosa
-some exotoxins are enterotoxins (more specific); they are exotoxins that are in GI tract

53
Q

What are the three modes of action for antimicrobials?

A

Bacteriostatic- stop division
Bactericidal – kill the bacteria; interfere with cell wall integrity
Bacteriolytic – lyse or break down microbes bacteria e.g. cytoantiobitoics kill them by lysing them

54
Q

Differentiate between, based on appropriate use, antiseptics, disinfectants, and sterilants.

A

Antiseptics- work against infection by destroying or inhibiting microorganisms on skin or mucus membranes

  • skin: soap, ethylene, iodine
  • mouth: mouthwash (antiseptic); peroxide; chlorhexidine

Disinfectants – kill most, not all microbes – NOT given to patients except alcohol on skin
-they DO NOT kill spores; DISINFECTING OUR EQUIPMENT IS NOT ADEQUATE

Sterilants – used to kill all microbial forms, even spores

  • autoclave
  • gas
  • chemical radiation
  • gamma sign; means it’s irradiated
  • filtered (but she has issues with calling it a sterilant)—> some viruses
55
Q

What are some antiseptics used in everyday life?

A

Soap – antiseptic that uses detergent to remove oils which aid microbial adherence
-we need to rub and disrupt the oil

Alcohol – used on skin and as a disinfectant on surfaces – dehydrates/extracts lipids and denatures proteins

  • inactivated by organics; so might be affected by what we have on our hands; it’s also quick to evaporate
  • not good against spores, protozoa cysts, and non-enveloped viruses (e.g. norovirus)
  • it’s good against bacteria and enveloped viruses
  • ethanal more effective than isopropanol
56
Q

What are antiseptics that are used in oral health and their mechanisms?

A

Chlorhexidine – disrupts bacterial cell membranes –

  • absorbed by teeth/gums
    • slow release; marketed to be antimicrobial and anti gingivitis; it can stain and some people have an allergic reaction

Fluoride- inhibits enolase; which is part of glycolysis

  • stannous fluoride (the stannous molecule causes the action more than the fluoride)
  • ADA says, stannous fluoride is anti-caries but NOT anti plaque and NOT anti gingivitus

Hydrogen peroxide- oxidizing agent

  • can damage tissue
  • need at least a 1:1 dilution

Other mouthwash types
Listerine - phenolic compounds; they disrupt enzymes/denatures proteins
Scope and cepacol- quaternary ammonium compounds - surfactants; the surfactants target lipids and membranes (so even though it goes after bacteria, it can go after our tissue)
-inactive for organic
-the BEST against bad breath

57
Q

What is the indicator organism for DISINFECTION?

A

does not kill spores- indicator organism is Mycobacterium tuberculosis;

58
Q

What are some properties of disinfectants?

A

Cheap and easy to use, germicidal action fast and sustained
Maintain efficacy when mixed with body fluids
Chemical characteristics – stable, does not corrode instrument

59
Q

What are the levels of disinfectants based on strength?

A

Low level– floors, countertops (quaternary ammonium); something that gets rid of most bacteria and enveloped viruses
-enveloped viruses more easier to get rid of because the envelope is a lipid bilayer (stolen from us); so it is easier to disrupt; (the non-envelope have outside protein which is strogner)

Intermediate level– semi-critical instruments – does not remove spores (alcohol + something, phenolic compounds, iodophors, bleach)
-indicator will be mycobacterium, which is harder to get rid of; will not destroy spores

High-level– nearing sterilization – for equipment you can’t sterilize (bleach, ethylene oxide 2% gluteraldehyde, peroxide)
-but you DO sterilize all equipment

60
Q

What is the mechanism for quaternary ammonium?

A

cationic detergents used for skin antisepsis

  • popular in dental offices; ; also can be used in MOUTH (scope/cephacol)
  • low level disinfectant—> floors
  • many viruses can survive and ALL spores survive; Pseudomonas can live in quaternary ammonium and can even form a biofilm!
61
Q

What is the mechanism for hydrogen peroxide? What are the measurements?

A

oxidizer – forms hydroxyl radicals – disinfect or sterilize

  • very concentration dependant
  • At high concentrations, it is a dangerous substance
  • rule of thumb: 3% used to disinfect; at 25% can be used to sterilize
  • at high concentrations, it will damage our tissue (hydroxyl radicals can oxidize)
62
Q

What is the mechanism of phenol?

A

disrupts enzymes/denatures proteins – rarely used- mouthwash

- First to be approved by ADA for anti-microbial/gingivitus
- Listerine
- don’t use as surface disinfectant because would be too toxic for us at the concentrations needed
63
Q

What is the mechanism of formaldehyde?

A

formalin (37% in water) - denatures proteins and nucleic acids by alkylating them– alkylating agent
-gluteraldehyde; distinctive smell; toxic in gas form and inactivated quicky—usually used in an enclosed box

64
Q

What is the mechanism of bleach?

A

oxidizing agent– high level disinfectant

  • chlorine is oxidizing agent
  • very corrosive
  • not great for expensive things because it is so corrosive
65
Q

What is the difference between an autoclave and an oven?

A

An autoclave uses water/pressure so it is faster.

66
Q

What do we use for gas sterilization? Why do we use gas sterilization

A

ethylene oxide – for heat sensitive materials

67
Q

What do we use for chemical sterilization?

A

2% gluteraldehyde – alkylated DNA and proteins
Chemiclave – alcohol and formaldehyde – little water – faster and pouches stay dry ; —the steam generated does not corrode the instrument because dries really quickly

68
Q

How do we use heat sterilization?

A

Heat (dry and moist)– Dry heat 320F for 2 hours or 340F for 1 hour. Coagulates proteins – safe for metal; will not dull or corrode

  • if dry —>longer (to denature protein)
  • if moist —> shorter (to denature protein) (water conducts the heat more efficiently)
69
Q

How do we use ethylene oxide/gas?

A

can be used for heat sensitive materials but SLOW (10-16 hours)

70
Q

How do we use 2% gluteraldehyde?

A

2% gluteraldehyde, hydrogen peroxide or peracetic acid will take 10-12 hours to kill spores – if NO organic material.

  • according to the EPA, this is considered an “immersion sterilant”, which means that if you have heat sensitive pieces of equipment, you can soak it in gluteraldehyde and it is considered sterile, but the minute you pull it out, it is no longer sterilee because in the air
  • also allergenic, not an environmental disinfectent
  • so this is toxic to tissues, but do not want this to be in the environment
71
Q

Classify Pasteurization as a sterilant or disinfectant

A

disinfectant only (can still have 20,000 bacteria/mL AFTER pasteurization —> not sterile)

	- short heat, doesn’t denature everything
	- other things pasteurized like juice
	- gets rid of bacteria like Lysteria/mycobacterium
72
Q

What time, temperature, and pressure is needed for an autoclave? How can you test to make sure your autoclave is working?

A

121 C for 15-20 minutes at pressure 15 psi (increase pressure to go shorter, etc. but this is the generic rule)

Since it should sterilize, check with bacterial spores (removing all life forms)

73
Q

State the appropriate uses for radiation and filtration. Identify how each works.

A

Radiation- UV light – thymine dimers (hoods, food prep areas); gamma (gloves)

  • DNA damage
  • packaged gloves (gamma irradiated)

Filters – pass through small pores that bacteria are excluded – technically not sterile (there could still be viruses present)

74
Q

What are the four types of selective media?

A

Enriched- support most
Selective – some grow some don’t
Differential – multiple grow but look different
Specialized – enriched for unique metabolic needs

75
Q

What factors influence success of the culture?

A

Biology of the organism – most important
Quality of the culture media
fastidious bacteria mean “fussy” eater
-site of infection; abx or immune response
-what type of media do you use?
-“colony morphology”—when they grow in a clump, has different characteristics

76
Q

What could you see if you were looking at hemolysis on a culture?

A

Hemolysis-break down of RBCs
Alpha – partial - green—partial breakdown of RBC’s-green because of breakdown of heme
Beta - complete - clear—completely breakdown of RBC’s
Gamma hemolysis - none (gamma=garbage—can’t do anything to RBC’s so no change)

77
Q

Brightfield vs. darkfield microscopes

A

Brightfield – two lenses – often need to stain prep to view

  • multiply together to get magnification
  • oil

Darkfield – condenser scatters light – organism illuminated against dark background – better resolution – good for thin/unstained preps

78
Q

What does a phase contrast microscope do?

A

rings shift phase of light; live specimens and internal structures
-rings adjust phase of light; we get nice contrast; can see internal and external structures (look at the nucleus); things like cilia and flagella—does not stain

79
Q

Give examples of direct microscopic examinations, differential stains, acid-fast stains, and fluorescent stains.

A

Direct exam - unstained preparation examined by brightfield, darkfield, or phase-contrast microscopy OR with simple stain
Differential stains – Gram stain is a classic
-gram staining is a differential stain based on cell wall
Acid fast stains - Mycobacterium
Fluorescent stains – view surface antigens and structures

Microbiology Final (2 decks)

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