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1003 Organisms and Environment > microbes > Flashcards

microbes Flashcards

1
Q

why does higher rates of cell division enable prokaryotes to have faster evolution?

A

there is a more likely occurance of a mutation and so the adaption for a new environment
pass on the advantageous allele

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2
Q

Do all bacteria poseess myxobacteria and outline their life cycle

A

not all bacteria have
spores are created and germinate to gram_ bacterium.
vegetative cells gilde to leave slime trails and then aggregate together to form masses and eventually fruitng bodies

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3
Q

Nmae some ways to grow microbes in lab

A

not all can be cultivated as their nutrient and environmental requirements are unknown

culture medium, plates or tubes or a liquid culture

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4
Q

name and describe types of microbes

4 types

A

bacteria - largest phylum
archaea - only 2 phlya, hard to culture, unknown
protzoa - unicelled eukaryotes
algae - terrestial and aqautic

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5
Q

discovery of micro-orgs/history brief….

A

took a while because there was no technolgoical developments.
robert koch did kochs postulates on how to idenetify a pathogen

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6
Q

what are extremophiles?

A

organisms that can grow in hostile conditions e.g. temp, pH and salt

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7
Q

what does cardinal temperatue mean?

A

cardinal (range) temperature varies between species

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8
Q 
What is (hyper)thermophiles optimum temp
(above... Degrees)
A 
greater than (80) 45 degrees
> only prokaryotes have been found to be these so generation times are quiicck
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9
Q

how do species gradients help us study microbes?

A

THEY ARE COLURFUL AND PRETTYY

p/s pigments found at the edges (coolest areas) whilst archea can survive at highest temperautres

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10
Q

How are (hyper)thermophiles adapted to survive

A

there are critical aa are different points to allow folding
hydrophobic interior with saturated FA
> this prevents protein denturation

(hyper)cell membranes DONT have fatty acids, have isoprene and ether links to form a monolayer = stability

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11
Q

decribe (hyper) thermophiles DNA composition

>differs in the hyper

A

increase amounts of soltes present

reverse DNA gyrase only in (hyper) to twist positive supercoils = heat stability

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12
Q

What are acidophiles and alkaliphiles optimum pH?

not the same as cytoplasmic pH which must be neutral

A

Acidophiles grow best below pH 5.5 alkaliphiles grow best above pH 8
extreme pH are not common environments
> alakliphiles use sodium instead of hydrogen as the protomotive force

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13
Q

Halophiles and halotolerents, what’s the difference?

A

Halophiles require NaCl for growth / halotolerents grows best in abscence of NaCl but can tolerate it

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14
Q

how does salt affect the cell?

A

It affects the osmotic gradient of cell making water extraction difficult

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15
Q

how are halophiles adapted to survive?

A

they have compatible solutes - highly soluble organic compounds that won’t interfere with protein hydration shell
e.g. sucrose, glycerol

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16
Q

Name different phases of bacterial growth

A

lag, exponential, stationary, death

This makes a plateu curve

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17
Q

problems with microscopic counts
problems with plate counts/viable counts
problems with spectrophotometer

A

can’t distinguish between live and dead cells, cells need to be immobile so flagella can cause cell fragementation/debris so inaccuracy in counting, cells stick too big amor cells too small, time consuming

Incubation time and conditions can have a huge effect on how well cells grow in a mixed population, this may obscure some populations due to different generation time, human error in piping or insuffient mixing

Dead cells, debris can influence opacity of sample

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18
Q

Waht is the difference between oxygenic and anoxygenic photosynthesis?
A anoxygenic only used by plants
B anoxygenic uses oxygen whilst oxygenic produces oxygen
C oxygenic uses H2O as an electron souce whilst anoxy uses H2S as electron source
D oxygenic uses H2S as electron source whilst anoxygenic uses H2O as electron source

A

OPTION
anoxygenic p/s is when photolysis does not occur, the electrons (reducing power) come from elsewhere

Anoxy doesnt USE oxygenic

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19
Q

What is a chemolithotroph ?
A organism that uses organic chemicals as energy source
B organism that uses inorganic chemicals as energy source
C organism that uses inorganic chemicals as carbon souce

A

Option B please (inorganic doesn’t have carbon in it!!! So can’t be an energy source)

organo oxidises organic compound for energy source. Only prokaryotes are lithotrophs
>waste from organo can be used by litho

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20
Q

TRUE OR FALSE

eukaryotes can do nitrogen fixation? (convert gas to organic nitrogen)

A

FALSE no known eukaryotes can do this.

bacteria species can be freeliving or symbiotic

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21
Q

name the 2 proteins that catalyse nitrogen fixation that make up enzyme Nitrogenase

A

dinitogenase

dinitrogenase reducatase

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22
Q

how do bacteria divide? explain generation time and how to calculate it

A

binary fission
Generation time is time from going to cell to daughter cells. A semilog graph is useful to estimate this
N=N₀2^n where small n is the generation time

23
Q 
Which stage (of microbe graph) do the essential nutrients run out and organism waste products build up to toxic levels?
A exponential
B lag
C death
D stationary
A

OPTION D PLEASE

stationary phase

24
Q

Psychrophile optimal growth range is:

A

below 15 degreesC

25
Q

True or faLse?

Cold shock proteins maintain other proteins activity and bind specific MRNA’s to facilitate their translation

A

TRUE

26
Q 
"Aerobes that can only use oxygen when it is present at levels lower than air" defines what?
A aerobes
B aerotolerents
C facualtives
D microaerophiles
E anaerobes
A

OPTION D

Microaerophiles use oxygen but only at specific concentrations and are poisoned by greater concentrations.

27
Q

Which of the following is the correct theoretical aspect of Koch’s Postulates?
A Suspected pathogen must be present in at least half of the cases of the disease and absent from the healthy cases
B Suspected pathogen must be present in all cases of disease and present in some of the healthy cases
C suspected pathogen must be absent in all cases of disease
D suspected pathogen must be present in all cases of disease and absent from the healthy cases
E none pf the above

A

suspected pathogen must be present in all cases of disease and absent from the healthy cases

28
Q

When does sporulation occur?

A

When an essential nutrient is exhausted

29
Q 
Which part of the soil has the most extensive microbial growth?
humus
topsoil
rhizosphere
bedrock
horizon
A

rhiziosphere (area around root)

30
Q

Hyperthermophile optimal growth range:

A

above 80 degrees C (the highest temp)

31
Q

explain what occurs during lag phase
A exponential decline of cells
B time between culture being inoculated into fresh media and significant growth
C cell population doubles at regular intervals
D death rate equal to birth ratw
E essential nutrient runs out

A

time between culture being inoculated into fresh media and significant growth
> cells need to adjust to new environment

32
Q

explain what occurs during exponenital phase
A time between culture being inoculated into fresh media and significant growth
B exponential decline of cells
C essential nutrient runs out
D cell population doubles at regular intervals
E death rate equal to birth rate

A

OPTION D

cell population doubles at regular intervals - healthiest state of growth

33
Q

myospore life cylce

A

germinate gram negative, glide and slime trails, aggregate, mound to form fruit bodies

34
Q 
What ion do alkaliphiles use to transport substances into the cells?
A hydrogen
B potassium
C calcium
D sodium
E chloride
A

OPTION D

they use sodium instead of hydrogen/protonmotive force

35
Q

characteristics of endospores?

A

Highly differentiated cells, have survival structures, Highly resistant to heat and harsh chemicals radiation, Only produced by some bacteria

36
Q

Which type of microscope uses polarised light?
bright field
flurorescense
phase contrast
differential interface contrast microscopy
atomic force

A

differential interface contrast microscopy (gives 3.d. like appearance)

37
Q

electron micrscopy types

A

TEM - thin sample cross section

SEM - thicker, can see cell surface

38
Q

describe atomic force micrscopy

A

measures FORCES so isnt light microscopy

39
Q 
What is the term for an extremophile that lives in high salinity?
thermophile
alkaliphile
halophile
acidophile
pyschophile
A

halophile

a-heat
b-alkali above 8
d-acid belwo 5.5
e-cold

40
Q

Which type of microscopy improves the contrast of the image without killing the cells?
bright field
darkfiled/phase contrast
atomic force

A

darkfield or phase contrast

41
Q

“tolerent” basic definition

A

this means that the substance is not needed for optimal growth but can tolerate it

42
Q

what Is the name of the proteins in the flagella molecular motor that act as stators?

A

MOT proteins

43
Q

Key history people involved in microbiology.

three people

A

Robert hooke - first discovery in 1673
Louis pasteur - heat can sterilise and microbes aren’t spontaneous or only air dwellers 1822
Robert Koch - bacteria +disease and developed the Koch postulates

44
Q

What is a colony of bacteria
A. While plate of bactera
B. Streak of bacteria on a plate
C. Single spot of bacteria on a plate

A

Option c please

45
Q 
Which of these types of microscopy can you see detailed structures of the cell?
A. Bright field
B. Phuse contrast 
C. Dark field 
D. None of the above
A

Option d please.
These are all light based so whilst dark and phase you can see more detail, ultrafine detail is not possible unless you get to electronic

Phase and dark you get a halo surrounding the image/cell of image

46
Q

Do all species of bacteria produce endospores? What are endospores?

A

No they don’t, only some species can do this

Highly differentiated cells that can withstand heat harsh chemicals and toxins (adverse enrolments)

47
Q

What would a terminal endosporium look like?

Nme the other 2 morphologies

A

Endosporium at the front of the bacteria.

Central and subterminal(at the tapered back)

48
Q

What causes vegetative cells to produce endospores?
A cell reaches a certain age
B essential nutrient wasted
C cell reaches a certain length

A

Option b

Cell foccues it’s energy on growing an endospores until the environmental conditions are back to normal

49
Q

What is an autotroph
A organism that uses organic compounds as carbon source
B organism that fixed its own carbon
C organism that gets its carbon from the food it ingests

A

OPTION B
a- heterotroph
c- also heterotroph

50
Q

What is chemotrophy
A Using chemicals as energy souce
B Using chemicals as carbon souce
C Using chemicals as energy and carbon source

A

Option A

Carbon is heterotrophy

51
Q

If you start with 3 cells how many cells would there be after 4 generations?

A

3 doubles 4 times so 48 cells. (3 x 16)

Or 2 to the power of 4 times 3 (16x3) [N=N₀2^n]

52
Q

After 2 hours of growth N (final cell number) is 10^8 and No (start cell number) is 2.5x10^7
What is generation time (g)?

A

N=N₀2^n
10^8 = 2.5x10^7 x 2^n
4=2^n
n= Number of generations is 2

g=t/n
So over 2 hours, generation time is 1 hour
g = 1 hour

53
Q

What causes the drop in oxygen downstream from a sewage outlet?
decrease in bacetrial pop
lack of resources
increase in bacterial population

A

The increase in bacterial population= more respire so less oxygen

(The nutrients are used up so high species diversity and then boom is gone)

54
Q

in freshwater, mcirobes can be planktonic or bethnic, what odes bethnic mean

A

bethnic - bottom of the lake/river

planktonic - floating

1003 Organisms and Environment (10 decks)

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