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MicroBiology Exam 2 > Exam 2 > Flashcards

Exam 2 Flashcards

(61 cards)

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1
Q

How do we categorize living organisms on the basis of energy source?

A

-phototroph and chemotroph

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2
Q

phototroph

A

-an organism that derives its energy from visible light. Metabolic energy is generated via phosphorolation

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3
Q

chemotroph

A
  • derives energy from a chemical source (without using light energy)
  • Metabolic energy is generated via fermentation or respiration
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4
Q

How do we categorize living organisms on the basis of carbon source?

A

-autotroph and heterotroph

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5
Q

autotroph

A

-an organism that uses carbon dioxide as a sole carbon source (via carbon dioxide fixation)

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6
Q

heterotroph

A

-requires an organic source of carbon

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7
Q

5 most abundant elements of a living cell:

A 
1-Carbon (heaviest)
2-Oxygen
3-Nitrogen
4-Hydrogen 
5-Phosphorus
6-Sulfur (lightest)
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8
Q

Why is molecular oxygen (O2) toxic to some microorganisms?

A

-it is toxic because it reacts easily with other things

Defense:
Catalyse protects against hydrogen peroxide (H2O2), catylase breaks it down into water and oxygen

Superoxide dismutase: used when there’s free oxygen in the cell, changes the oxygen to peroxide (2O2- + 2H+ > H2O2 + O2-reduced product

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9
Q

what do the minimum, optimum, and maximum temperatures of microbial growth describe?

A

psychrophiles: 0-20 degrees celsius
mesophiles: 20-40~45 degrees celsius
thermophiles: 45-95 degrees celsius

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10
Q

bacteria that grow in specialized environments

A
  • geogemaboraciae
  • halophiles
  • barophiles
  • acidophiles
  • alkaliphiless
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11
Q

geogemaboraciae

A

can grow at 121 degrees celsius (formed at bottom of ocean; raises boiling point to ~125 degrees celsius)

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12
Q

halophiles

A

grow best at high salt environments (ocean ~3.5% salt)

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13
Q

barophiles

A

grow best at high hydrostatic pressure (380 atm (38 MPa or above)

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14
Q

acidophiles

A

microorganisms that grow best at low pH (typically 4 and below)

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15
Q

alkaliphiles

A

grow best at high pH (10.10 or above)

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16
Q

how are certain bacteria that grow at extremely low pH used for microbial mining?

A

used to get metals out of low grade ores; acidibiothilus has the ability to soludize metal; recover it, purity it, and seal it

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17
Q

what are the most common modes of microbial cell division?

A
  • binary fission
  • longitudinal binary fission
  • multiple fission
  • budding
  • fragmentation
  • transversed binary fission

*picture on phone

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18
Q

FtsZ ring:

A
  • essential for the growth of E. Coli
  • attached to cell membrane and cell wall, as the ring contracts it brings cell wall together and pinches off into two cells
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19
Q

what influences double (generation) time of bacterial culture

A
  • time for a bacterial cell to grow and divide

- factors vary among chemical and physical conditions

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20
Q

what is the exponential growth equation?

A

logN=logN0 + 0.3 (t-t0)/g

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21
Q

what factors limit exponential growth of bacterial populations in the real world?

A

-cell death and nutrient depletion can limit exponential bacterial growth

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22
Q

Name the 4 phases of the bacterial growth curve

A
  • lag phase (slow growth)
  • exponential phase (very rapid growth)
  • stationary phase (steady growth)
  • death and decline (growth slows & stops)
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23
Q

microbiostatic

A

-chemical or physical inhibition of microbes

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24
Q

microbicidal

A

-permanently inactivate particular microbes (endospores are resistant)

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25
sterilizing agents
removal of ALL microbes including viruses and endospores (prions resistant - infections proteins)
26
Can an object be partially sterile?
No, an object cannot be partially sterile.
27
thermal death time
time it takes to kill microorganisms at a certain temperature
28
thermal death point
temperature it takes to kill in 10 minutes
29
moist heat
doesn't have to be as hot because it absorbs heat better
30
dry heat
must be hotter because of higher specific heat (doesn't absorb heat as easily)
31
How can cold be used to control microbial growth?
refrigeration slows microbial growth (slows the growth of the enzymes that spoil food)
32
How can desiccation be used to control microbial growth?
dries organisms out; need water as solvent for enzyme reactions
33
How can osmotic pressure be used to control microbial growth?
high salt or sugar inhibits growth by pulling water out of the cell
34
How can filtration be used to control microbial growth?
filtration works by small pore size, also bacteria has negatively charged surface so if filter is positively changed it's easier
35
how can irradiation be used to control microbial growth?
- UV and Ionizing Radiation - UV is not powerful enough to break down DNA, it just causes mutations like thiamine dimers (lethal) -ionizing radiation (X-rays & gamma rays) have high power to break DNA bonds
36
disinfectants
-microbicidal agent that is used on inanimate objects and surfaces (does not eliminate all of them)
37
antiseptic
-chemical used on skin or tissue to disinfect
38
sanitization
-process of disinfecting places and utensils used by public to reduce # of pathogenic microbes to meet pH standards (silver ware)
39
4 classes of chemical agents disrupt cell membranes and denature proteins?
1. phenol (carbolic acid) 2. phenolics (phenol derivatives) 3. alcohols 4. surfactants
40
phenol coefficient
phenol coefficient of 1 means it's as effective as phenol | > 1 means more effective
41
large family of surfactants
quardenary ammonium compounds
42
4 classes that inactivate enzymes reacting with chemical groups essential for activity?
- halogens - heavy metal (silver nitrate drops used in eyes of infants for gonorrhea) *now use iron - peroxides - gaseous agents (like ethylene oxide used to disinfect plastics)
43
what 2 classes of chemical agents kill or inhibit microbial growth by other mechanisms?
- dyes (inhibit DNA or cell wall) | - concentrated acids & bases
44
Paul Ehrlich
- pioneer in chemotherapy | - looked for cure to syphilis, mercury worked but was too toxic *came up with arsphenamine (salvarsan)
45
Basic principle that guides search for new chemical compounds that will destroy microbes in vivo w/o harming the patient?
-selective toxicity
46
selective toxicity
-the ability of a chemotherapeutic agent to kill or inhibit disease - causing microbes w/o harming the patient
47
what distinguishes a drug from an antibiotic?
- drugs are manufactured in the lab | - antibiotics are naturally occurring
48
how does sulfanilamide (the first sulfa drug) exert its antimicrobial effect?
competes with papa to inhibit production of folic acid this is important because folic acid is needed for the production of purine and pyrimidine base (these are necessary for DNA replication and synthesis if no folic acid is being made, no more DNA will be produced
49
what genera of bacteria and fungi produce most of our medically important antibiotics?
streptomycin (& related genera) & bacillus produce huge number of antibiotics penicillium and tetracycline inhibit cell wall synthesis
50
narrow spectrum antibiotics
-are effective against only one group of microorganisms >gram positive only bacteria (penicillin) easier to penetrate cell wall of g-positive cells >gram negative: polymyxins B & E
51
broad spectrum antibiotics
-are effective against more than one group of microorganisms - g-positive and g-negative >chloramphenicol >tetracycline >cephalosporin
52
4 major modes of action by which antibiotics kill microbial cells
1. inhibition of cell wall synthesis (penicillins, cephalosporins, bacitracin) 2. inhibition of protein synthesis a. transcription (rifamycins) b. translation (cholarmpthemincoe, macrocodes, ahminoglycosides, tetracyclines) (bacteria have different protein for synthesis than eukaryotic cells) 3. inhibition of DNA replication (guinilones, antinomycin, mitomycin) 4. Damage to cell membrane a. antibacterial (gramicidin, polymyxin B) b. anti fungal (amphotericin B, nystatin)
53
mode of penicillin
- uses inhibition of cell wall synthesis | - benzylpenicillin (penicillin G) (has beta lactam ring): semi synthetic be naturally occurring but modified in lab
54
mode of tetracycline (semi-synthetic)
inhibits reading of RNA; block protein synthesis and inhibits second step in protein synthesis
55
how do antibiotic resistant microorganisms of antibiotic resistance?
-when dosage isn't completed and not all microbes are killed so they multiply and are resistant/also mutations
56
most common mechanisms of antibiotic resistance
- is a naturally selective process... they produce enzymes to break down antibiotics - antibiotics kill all but the resistant cell, and those cells reproduce
57
problems that can be associated w/ the use of antibiotics
- toxic side effects (streptomycin) - allergic reactions (penicillin) - overuse can suppress immune system - destruction of normal microbiota - resistance
58
what are two major themes that genetics deals with?
-heredity and variation
59
what is meant by a complementary DNA strand and a template ?
picture on review
60
6 enzymes essential for DNA replication
1. DNA helicase 2. single strand DNA binding protein: (binds to and stabilizes unwound single DNA strand) 3. primase: synthesizes short RNA primers (RNA polymerase); synthesizes primer that DNA polymerases need to recreate (~10 bases) * polymerase can't just attach anywhere, they have to have a primer to which they can hook new nucleotides *hook onto 3' from red strand * RNA doesn't need primer, just template 4. DNA polymerase III: extends the primers; the major DNA replication enzyme 5. DNA polymerase I: removes RNA primers and replaces them with DNA (~10 bases of DNA to replace RNA) 6. DNA ligase: seals newly synthesized pieces of DNA (okazaki fragments) together
61
what is a gene?
look later

MicroBiology Exam 2 (1 decks)

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