microbes Flashcards
why does higher rates of cell division enable prokaryotes to have faster evolution?
there is a more likely occurance of a mutation and so the adaption for a new environment
pass on the advantageous allele
Do all bacteria poseess myxobacteria and outline their life cycle
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
Nmae some ways to grow microbes in lab
not all can be cultivated as their nutrient and environmental requirements are unknown
culture medium, plates or tubes or a liquid culture
name and describe types of microbes
4 types
bacteria - largest phylum
archaea - only 2 phlya, hard to culture, unknown
protzoa - unicelled eukaryotes
algae - terrestial and aqautic
discovery of micro-orgs/history brief….
took a while because there was no technolgoical developments.
robert koch did kochs postulates on how to idenetify a pathogen
what are extremophiles?
organisms that can grow in hostile conditions e.g. temp, pH and salt
what does cardinal temperatue mean?
cardinal (range) temperature varies between species
What is (hyper)thermophiles optimum temp (above... Degrees)
greater than (80) 45 degrees > only prokaryotes have been found to be these so generation times are quiicck
how do species gradients help us study microbes?
THEY ARE COLURFUL AND PRETTYY
p/s pigments found at the edges (coolest areas) whilst archea can survive at highest temperautres
How are (hyper)thermophiles adapted to survive
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
decribe (hyper) thermophiles DNA composition
>differs in the hyper
increase amounts of soltes present
reverse DNA gyrase only in (hyper) to twist positive supercoils = heat stability
What are acidophiles and alkaliphiles optimum pH?
not the same as cytoplasmic pH which must be neutral
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
Halophiles and halotolerents, what’s the difference?
Halophiles require NaCl for growth / halotolerents grows best in abscence of NaCl but can tolerate it
how does salt affect the cell?
It affects the osmotic gradient of cell making water extraction difficult
how are halophiles adapted to survive?
they have compatible solutes - highly soluble organic compounds that won’t interfere with protein hydration shell
e.g. sucrose, glycerol
Name different phases of bacterial growth
lag, exponential, stationary, death
This makes a plateu curve
problems with microscopic counts
problems with plate counts/viable counts
problems with spectrophotometer
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
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
OPTION
anoxygenic p/s is when photolysis does not occur, the electrons (reducing power) come from elsewhere
Anoxy doesnt USE oxygenic
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
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
TRUE OR FALSE
eukaryotes can do nitrogen fixation? (convert gas to organic nitrogen)
FALSE no known eukaryotes can do this.
bacteria species can be freeliving or symbiotic
name the 2 proteins that catalyse nitrogen fixation that make up enzyme Nitrogenase
dinitogenase
dinitrogenase reducatase
how do bacteria divide? explain generation time and how to calculate it
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
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
OPTION D PLEASE
stationary phase
Psychrophile optimal growth range is:
below 15 degreesC
True or faLse?
Cold shock proteins maintain other proteins activity and bind specific MRNA’s to facilitate their translation
TRUE
"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
OPTION D
Microaerophiles use oxygen but only at specific concentrations and are poisoned by greater concentrations.
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
suspected pathogen must be present in all cases of disease and absent from the healthy cases
When does sporulation occur?
When an essential nutrient is exhausted
Which part of the soil has the most extensive microbial growth? humus topsoil rhizosphere bedrock horizon
rhiziosphere (area around root)
Hyperthermophile optimal growth range:
above 80 degrees C (the highest temp)
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
time between culture being inoculated into fresh media and significant growth
> cells need to adjust to new environment
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
OPTION D
cell population doubles at regular intervals - healthiest state of growth
myospore life cylce
germinate gram negative, glide and slime trails, aggregate, mound to form fruit bodies
What ion do alkaliphiles use to transport substances into the cells? A hydrogen B potassium C calcium D sodium E chloride
OPTION D
they use sodium instead of hydrogen/protonmotive force
characteristics of endospores?
Highly differentiated cells, have survival structures, Highly resistant to heat and harsh chemicals radiation, Only produced by some bacteria
Which type of microscope uses polarised light?
bright field
flurorescense
phase contrast
differential interface contrast microscopy
atomic force
differential interface contrast microscopy (gives 3.d. like appearance)
electron micrscopy types
TEM - thin sample cross section
SEM - thicker, can see cell surface
describe atomic force micrscopy
measures FORCES so isnt light microscopy
What is the term for an extremophile that lives in high salinity? thermophile alkaliphile halophile acidophile pyschophile
halophile
a-heat
b-alkali above 8
d-acid belwo 5.5
e-cold
Which type of microscopy improves the contrast of the image without killing the cells?
bright field
darkfiled/phase contrast
atomic force
darkfield or phase contrast
“tolerent” basic definition
this means that the substance is not needed for optimal growth but can tolerate it
what Is the name of the proteins in the flagella molecular motor that act as stators?
MOT proteins
Key history people involved in microbiology.
three people
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
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
Option c please
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
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
Do all species of bacteria produce endospores? What are endospores?
No they don’t, only some species can do this
Highly differentiated cells that can withstand heat harsh chemicals and toxins (adverse enrolments)
What would a terminal endosporium look like?
Nme the other 2 morphologies
Endosporium at the front of the bacteria.
Central and subterminal(at the tapered back)
What causes vegetative cells to produce endospores?
A cell reaches a certain age
B essential nutrient wasted
C cell reaches a certain length
Option b
Cell foccues it’s energy on growing an endospores until the environmental conditions are back to normal
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
OPTION B
a- heterotroph
c- also heterotroph
What is chemotrophy
A Using chemicals as energy souce
B Using chemicals as carbon souce
C Using chemicals as energy and carbon source
Option A
Carbon is heterotrophy
If you start with 3 cells how many cells would there be after 4 generations?
3 doubles 4 times so 48 cells. (3 x 16)
Or 2 to the power of 4 times 3 (16x3) [N=N₀2^n]
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)?
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
What causes the drop in oxygen downstream from a sewage outlet?
decrease in bacetrial pop
lack of resources
increase in bacterial population
The increase in bacterial population= more respire so less oxygen
(The nutrients are used up so high species diversity and then boom is gone)
in freshwater, mcirobes can be planktonic or bethnic, what odes bethnic mean
bethnic - bottom of the lake/river
planktonic - floating
