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211 - microbiology > block A- general microbiology > Flashcards

block A- general microbiology Flashcards

1
Q

name different types of microorganisms?

A

bacteria
fungi
viruses

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2
Q

why are microorganisms improtant?

A

the production of food and drinks
decomposition of organic matter
the maintenance of the earths ecosystem
theyre vital in human health - both causing and helping

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3
Q

what can understanding microorganisms’ biology and behaviour help with?

A

its essential for the development of new medical treatments
improvement of food safety
the management of enviromental resources

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4
Q

what is the oldest form of life?

A

microorganisms

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5
Q

what are stromatolites?

A

theyre fossilized stromatolites with are layered structures formed by the growth of microbial communities
theyre were formed about 3.5 billion years ago

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6
Q

how long ago was it thought that the first microorganisms emerged?

A

about 3.5-4 billion years ago

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7
Q

where were the first fossils found?

A

greenland

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8
Q

what makes up the largest mass of living material on earth?

A

microorganisms

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9
Q

how much living mass material is there on the world and how many times bigger than all the rest of the living material on the planet?

A

around 5 x 10^30 grams is the mass of all the bacteria found in the world
thats 2.5x the rest of the living material on the world

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10
Q

where is most of the biomass found?

A

its mostly found in the ocean and in the soil

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11
Q

what is the carbon cycle?

A

its the decomposition of organic matter which releases CO2 through respiration - i think microbes play a massive part in this cycle

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12
Q

what is the nitrogen cycle?

A

its a cycle that concerts nitrogen gas into forms that plants and animals can use like ammonia, nitrate and nitrile
its actually called nitrogen fixation and is essential for the growth of plants and the survival of many animals

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13
Q

what happens if the soil becomes depleted in nitrogen?

A

theres a break in productivity

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14
Q

what are some of the major processes which are part of biogeochemical cylcles that microbes help with?

A

the carbon cycle, the nitrogen cycle, sulpher cycle, phospherous cycle and iron cycle

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15
Q

what is the sulpher cycle?

A

some microorganisms can oxidise sulpher compounds like hydrogen sulphide and convert it into sulphuric acid
this process plays a critical role in the geochemical cycling of sulpher and the formation of sulpher minerals

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16
Q

what is the phosphorous cycle?

A

its involved in the release of phosphate from minerals which is an essential nutrient for plants and animals
they also play a role in the formation of bones and teeth by converting phosphates into hydroxyapatite

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17
Q

what is the iron cycle?

A

some microorganisms can oxidise iron compounds such as ferrous iron and convert them into ferric iron
this process plays a critical role in the geochemical cycling of iron and the formation of iron minerals

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18
Q

what extremes can microorganisms survive in?

A

high temperatures
low temperatures
high pressure
high salinities
high radiation
high acidity

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19
Q

what types of bacteria can survive at hogh temperatures?

A

thermophiles and hyperthermophiles
these can survive at temps as high as 80 degrees
theyre found in volcanic hot springs, guysers and deep-sea hydrothermal vents and subsurface oil resivoirs

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20
Q

what types of microorganisms can survive at high pressures? and where are they found?

A

piezophils can survive and grow at pressures as high as 1800x atmospheric pressures
theyre found in subsurface oil resivoirs and deep-sea hydrothermal vents

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21
Q

what types of microorganisms can survive at high salt concentrations and where are they found?

A

hapophils - theyre found in salt flats and salt mines

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22
Q

what types of microorganisms survive at high radiation and where are they found?

A

deinococcus radiodurans can survive and grow in inviroments with hoigh levels of radiation like nuclear waste sites

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23
Q

what types of microorganisms survive in high acidity habitats and where are they found?

A

acidophils
theyre found in acid mine drainage, acid hot springs and acid soils

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24
Q

what microorganisms are needed in symbiosis in some plant species?
And what do they do?

A

rhizobia
these live in the roots and convert atmospheric nitrogen into a form that plants can use
this is essential for the growth of plants

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25
Q

how do microorganisms live in symbiosis with animals?

A

microorganisms digest their food
e.g. ruminant microbes break down plant material and terminte microbes digest wood

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26
Q

how do microorganisms live in symbiosis with humans?

A

the gut microbiome is important for digestion, metabolism, immunity and the production of vitamins and other essential compounds

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27
Q

how does marine life live in symbiosis with microorganisms?

A

microorganisms are responsible for most primary production, this is the process of converting dissolved inorganic compounds into organic compounds
these form the basis of the oceanic food web
they also play an important role in the cycling of nutrients like carbon, nitrogen and phospherous

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28
Q

how do microorganisms help in the soil?

A

they breakdown dead plants and animals to release nutrients back into the soil
they also help to maintain the soil structure by forming microbial aggregates which help to retain the water and air

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29
Q

what are the main characteristics of microbial cells?

A

prokaryotes
- they have no membrane enclosed organelles with no nucleus
- generally smaller than eukaryotic cells

archaea and bacteria-
- DNA is enclosed in a membrane bound nucleus
- cells are generally larger and more complex
- contain organelles

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30
Q

what are the characteristics of wukaryotic cells?

A
  • their DNA is linear and found in the nucelus
  • theyre assiciated with proteins that help in the folding of DNA
  • mitochondria are thought to have arisen from bacteria
  • they usually have more than one chromosome, with generally 2 copies of each chromosome
  • during cell division, the nuclus divides by mitosis
  • during sexual reproduction, the genome is halfed by meiosis
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31
Q

what are the characteristics of prokaryotic cells?

A

they generally have a single, circular DNA molecule called a chromosome
the DNA aggragates to form the nucleoid region
prokaryotes also may have small amounts of extrachromosomal DNA called plasmids that confer special properties

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32
Q

what is the adaptive advantage to do woth plasmids?

A

the prokaryotes can swap plasmids, this causes a massive problem related to antibiotic resistance

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33
Q

how much bigger is the human genome compared to e. coli - the amount of DNA per cell and the number of genes?

A

humans have 1000x more DNA per cell and 7x more genes than E coli

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34
Q

what does metabolism mean?

A

chemical transformation of nutrients

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35
Q

what does reproduction mean?

A

generation of two cells from one

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36
Q

what does differentiation mean?

A

synthesis of new substances or structures that modify the cell (only in some microbes)

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37
Q

what does communication mean?

A

the generation of, and response to, chemical signals (only in some microbes)

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38
Q

what does movement mean?

A

via self-propulsion, many forms of it in microbes

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39
Q

what does evolution mean?

A

genetic changes in cells that are transferred to the offspring
its the process of chnage over time that results in new varieties and species of organisms

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40
Q

what is phylogeny?

A

its the evolutionary relationship between organisms
relationships can be deduced by comparing genetic information in the diffeent specimens
rRNA is excellent for determining phylogeny
relationships visualised on a phylogenetic tree

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41
Q

how can you assess evolution by phylogeny?

A

you can look at the same gene across different microbes and compare the simialrity and difference of a few genes picked out from the whole genome

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42
Q

what are the three distinct lineages of cells called domains?

A

bacteria
archaea
eukarya

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43
Q

how did evolution proceed from the last universal common ancestor?

A

it proceeded to form two domains- bacteria and archaea- then archaea leater diverged to form two domains- archaea and eukarya

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44
Q

what are evolutionary relationships displayed on?

A

phylogenetic tree

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45
Q

what does habitat mean?

A

its the environment in which a microbial population lives

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46
Q

what does microbial community mean?

A

its when microbes exist in nature in populations of interacting assemblages

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47
Q

what does ecosystem mean?

A

this refers to all living organisms and physical and chemical constituents of their environment

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48
Q

what is microbial ecology?

A

its the study of microbes in their natural enviroment

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49
Q

what is diversity and abundances of microbes controlled by?

A

resources (nutrients) and enviromental conditions (temp, pH and O2)

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50
Q

what can the activities of microbial communities affect?

A

they can affect the chemical and physical properties of their environment
- ecosystems are greatly influenced by microbial activities
- microorganisms change the chemical and physical properties of their habitats through their activities for example, the removal of nutrients from the envirmoment and the excretion of waste

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51
Q

are microbes typically more harmful or beneficial?

A

there is many more benifitial ones compared to harmful

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52
Q

what are the positive effects on agriculture by microorganisms?

A

nitrogen-fixing bacteria
cellulose-degrading microbes in the rumen
regeneration of mutrients in soil and water

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53
Q

what are the negative impacts of microorganisms on agriculture?

A

they cause diseases in plants and animals

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54
Q

what are the negative effects caused by microorganisms on food?

A

they can cause food spoilage- for many foods so methods of preservation are needed

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55
Q

what are the positive imapcts of microorganisms on food?

A

microbial transformations - typically fermentations
- dairy products (cheese, yogurt and buttermilk)
- other food products (sauerkraut, pickles, leavened bread and beer)

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56
Q

how do microorganisms help in energy and the enviroment?

A

they help produce biofuels like methane, ethanol and hydrogen
they also help clean up pollutants (bioremeduation)

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57
Q

how do microorganisms help in energy and in the environment?

A

exploitation of microbes for the production of antibiotics, enzymes and various chemicals
genetic engineering of microbes to generate products of value to humans, such as insulin

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58
Q

who are influential figures involved in the discovery of microorganisms?

A

robert hooke- first to describe microbes
antoni van leeuwenhoek - the first to describe bacteria
ferdinand cohn - founded the feild of bacterial classification and discovered bacterial endospores

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59
Q

what did louis pasteur do?

A
  • discovered that living organisms discriminate between optical isomers
  • discovered that alcoholic fermentation was a biologically mediated process
  • disproved theory of spontaneous generation- this lead to the development of methods for controlling the growth of microorganisms
  • developed vaccines for anthrax, fowl cholera and rabies
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60
Q

what did koch do?

A

Robert Koch (1843–1910)
Demonstrated the link between microbes and infectious diseases
Identified causative agents of anthrax and tuberculosis
Koch’s postulates (Figure 1.20)
Developed techniques (solid media) for obtaining pure cultures of microbes, some still in existence today
Awarded Nobel Prize for Physiology and Medicine in 1905

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61
Q

what is the central dogma of molecular biology?

A

replication, transcription and translation

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62
Q

what is supercoiled DNA?

A

the DNA is further twisted to save space

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63
Q

what are positive and negative supercoiling of the DNA?
(Not the positives and negatives of supercoiling)

A

negative- the double helix is underwound
positive - the double helix is overwound

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64
Q

what is relaxed DNA?

A

the DNA has a number of turns predicted by number of base pairs
negative supercoiling is predominantly found in nature

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65
Q

what does DNA gyrase do?

A

it introduces supercoils into DNA
this is an enzyme that packs the DNA, if you inhibit the enzyme, the cell will stop growing

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66
Q

what do you have to do to one of the strands so it can become supercoiled?

A

you have to cut one of the strands then it can become super coiled

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67
Q

what does the DNA gyrase so to DNA supercoiling?

A

it catalyses the DNA supercoiling

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68
Q

what is a chromosome?

A

its arge and encodes all the essential genes and more

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69
Q

what is a plasmid?

A

small, many copies, non-essential bt advantageous genes (e.g. antibiotic resistance)

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70
Q

what are transposable elements?

A

segment of DNA that can move from one site to another site on the same or different DNA molecule
theyre inserted into three main types- insertion sequences, transposes and special viruses

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71
Q

what are characteristics of plasmids?

A

they replicate seperately from the chromosome
the majority of them are double stranded
most are circular
they’re normally beneficial for the cell
they’re not extracellular
some can auto replicate
its expendable and usually doesnt have genes for growth under all conditions

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72
Q

what are some of the characteristics of chromosomes?

A

they’re genetic elements with housekeeping genes
the presence of genes is necessary for genetic element for it to be called a chromosome

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73
Q

what type of bacterium are 70% of antibiotics made up of?

A

streptomyces

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74
Q

what does a genetic element have to have to be called a chromosome?

A

the presence of genes

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75
Q

what do sigma factors recognise?

A

they recognise 2 highly conserved regions of the promoter
theyre called the ‘pribnow box’ and the ‘-35 region’

76
Q

where is the pribnow box located?

A

10 bases before the start of transcription (-10 region)

77
Q

where is the -35 region located?

A

~35 bases upstream of transcription

78
Q

what factors govern promoter recognition of RNAP?

A

sigma factors

79
Q

what does polycistronic mean?

A

it means that multiple proteins can be coded form one mRNA

80
Q

what is a unit of transcription?

A

its the unit of chromosome bounded by sites where transcription of DNA to RNA is initiated and terminated

81
Q

what are the 3 types of rRNA?

A

16S
23S
5S

82
Q

how long are mRNA half lives?

A

only a few mins

83
Q

what is a polyextronic mRNA molecule?

A

an mRNA encoding a group of co-transcribed genes

84
Q

are RNA polymerases the same in the three domains of life?

A

no, theyve all got slightly different structures and subunits
eukaryotes have diffrent types of RNA polymerases but bacteria and eukaryotes only have one type each

85
Q

how is gene expression regulated?

A

its regulated in the form of activation and repression
it takes place before the initiation site

86
Q

what are homodimeric proteins?

A

they’re proteins composed of two identical polypeptides

87
Q

what do protein dimers ineract with?

A

inverted repeats on DNA

88
Q

how does the short half life of mRNA help the cell?

A

it prevents the production of unneeded proteins

89
Q

what does the regulation of transcription usulally require?

A

proteins that can bind to DNA

90
Q

what are the different outcomes that are possible after DNA binding?

A
  1. DNA binding protein may catalyse a specific reaction on the DNA molecule
  2. the binding event can block transcription (negative regulation)
  3. the binding event can activate transcription (positive regulation)
91
Q

what is an inducer?

A

its a substance that induces enzyme synthesis

92
Q

what is a co-repressor?

A

its a substance that represses enzyme synthesis

93
Q

what do effectors mean?

A

its the collective name for inducers and repressors

94
Q

what is an operon?

A

its a cluster of genes arranged in a linear fashion whose expression is under control of a single operator

95
Q

what is the operator and what binds to it?

A

its located downstream of the promoter and transcription is physically blocked when the repressor binds to the operator

96
Q

what can enzyme induction be controlled by?

A

repressors and inducers

97
Q

what does the addition if the inducer do to transcription?

A

it inactivates the repressor and transcription proceeds

98
Q

what type of control is a repressor part of?

A

negative control

99
Q

what is a repressor’s role?

A

its inhibitory

100
Q

what is negative control?

A

its a regulatory mechanism that stops transcription

101
Q

what is repression?

A

its preventing the synthesis of an enzyme in response to a signal
enzymes affected by repression make up a small fraction of total proteins
this typically affects anabolic enzymes

102
Q

how does enzyme inhibition in the arginine operon work?

A

if arginine is present in the external environment - it binds to the repressor and blocks the transcription of the synthesis of arginine
if arginine is not present - arginine synthesis isn’t inhibited and the cell can make its own arginine

103
Q

what is induction?

A
  • its the production of an enzyme in response to a signal
    this typically affects catabolic enzymes like the lac operon
    enzymes are then synthesised only when they’re needed
    these enzymes are only made when theyre needed so that no energy is wasted
104
Q

what happens in enzyme induction in the lactose operon if there isn’t any lactose ?

A

this is the gene that the cell uses to catalyse the lactose

if there isnt any lactose then transcription is blocked because the repressor isnt blocked

105
Q

what is positive control?

A

regulator protein activated the binding of RNA polymerase to DNA

106
Q

what happens in maltose catabolism in E, coli?

A

maltose activator protein cant bind to DNA unless it first binds maltose
maltose operon is responsible to produce the gene so the cell can use the maltose
if there isnt any maltose then the activator protein doesnt bind to the activator binding site and theres no transcription of the gene
activator proteins bind specifically to certian DNA sequences called activator binding site

107
Q

what is the activator binding site?

A

its a specific site where activator proteins bind specifically to certain DNA sequences

108
Q

how do promoters of positively controlled operons bind to RNA polymerase?

A

they bind weakly

109
Q

how close/ far can the activator binding site be from the promoter?

A

it could be very bear it or kilobases away, if its kilobases away, it could bend the DNA

110
Q

what may activator proteins do when they help RNA polyerase recognise the promoter?

A

they may cause a change in the DNA structure or may interact directly with RNA polymerase

111
Q

where are the genes for maltose?

A

theyre spread out acctoss the chromosome in several operons

112
Q

what does each operon have?

A

an activator binding site

113
Q

what is a regulon?

A

its where multiple operons are controlled by the same regulatory protein
they also exist for negatively controlled systems

114
Q

what are global control systems?

A

regulate expression of many different genes simultaneously

115
Q

what is an example of global control?

A

catabolite repression
synthesis of unrelated catabolic enzymes is repressed if glucose is present in growth medium
lac operon is under contorl of catabloite repression
this ensures that the best carbon and energy source is used first

116
Q

what is diauxic growth?

A

its two exponential growth phases

117
Q

what is transcription controlled by in catabolite repression?

A

its controlled by an activator protein and is a form of positive control

118
Q

what type of molecule is cyclic AMP and what is it derived from?

A

its derived form a nucleic acid precursor and is a regulatory nucleotide

119
Q

what does CRP stand for?

A

cyclic AMP recpetor protein and its an activator protein

120
Q

how many catabolic operons are affected by catabolite repression?

A

dozens
enzymes for degrading lactose, maltose ans other common carbon sources

121
Q

what are flagellar proteins controlled by?

A

catabolite repression
this means that the flagella dont have to swim in search of nutrients

122
Q

explain the basis of catabolite repression?

A
  • the operon is off when glucose and lactose are present
  • when neither is present, the repressor is bound
  • when only glucose is present, the operon is off because the lac repressor is bound and because CAP isnt bound
  • when only lactose is bound, the operon is on
123
Q

the more regulation there is, the what?

A

the better you can fine tune the process

124
Q

how can prokaryotes regulate cellular metabolism in response to environmental fluctuations?

A

external signals are transmitted directly to the target

125
Q

what is signal transduction?

A

its when external signals are detected by a sensor and transmitted to the regulatory machinery

126
Q

what types of systems are most signal transduction systems?

A

two-component regulatory systems

127
Q

what 2 different proteins make up the two component regulatory system?

A

sensor kinase- this is in the cytoplasmic membrane and detects environmental signal and auto phosphorylates
response regulator- this is in the cytoplasm and is a DNA binding protein that regulates transcription

128
Q

what auto-phosphorylates the receptor kinase?

A

the enviromental signal

129
Q

what is the role of the feedback loop in two-component reguatory systems?

A

to terminate the signal

130
Q

how many two-component systems are there in E. coli?

A

almost 50

131
Q

what are some examples of two-component systems in E. coli?

A

phosphate assimilation
nitrogen metabolism
osmotic pressure response

132
Q

do archaea have two component regulatory systems?

A

yeah, some do

133
Q

do some signal transduction systems have multiple regulatory elements?

A

yeah

134
Q

what are modified two-component systems used in chemotaxis?

A

they sense temporal changes in attractants or repellents
regulate flagellar rotation

135
Q

what are the 3 main steps of the regulation of chemotaxis?

A
  1. response to signal
  2. controlling flagellar rotation
  3. adaptation
136
Q

what is involved in the ‘response to signal’ step of regulation of chemotaxis?

A

sensory proteins in cytoplasmic membrane sense attractants and repellents
methyl-accepting chemotaxis proteins (MCPs) bind attractant or repellent and initiate flagellar rotation

137
Q

what is involved in the ‘controlling flagellar rotation’ step of the regulation of chemotaxis?

A

controlled by CheY protein
this results in counterclockwise rotation and runs
CheY-P results in clockwise rotation and tumbling

138
Q

what happens in the ‘adaptation’ step of regulation of chemotaxis?

A

feedback loop- this allows the system to reset and continue to sense the presence of a signal
this involves modifications of MCPs

139
Q

what are photsotaxis?

A

movement towards light
the light sensor replaces MCPs

140
Q

what are aerotaxis?

A

movement towards oxygen
redox protein monitors oxygen levels

141
Q

what is quorum sensing?

A

its the mechanism by which bacteria assess their population density

142
Q

what does quorum sensing ensure?

A

it ensures that there’s a sufficient number of cells that are present before initiating a response that, to be effective, requires a certain cell density like toxin production in pathogenic bacteria

143
Q

each species of bacteria produces a specific autoinducer molecule, what do these do?

A

they diffuse freely accross the cell envolope and reach high concentrations inside the cell only if many cells are near
binds to specific activator protein and triggers transcription of specific genes

144
Q

what is acyl homoserine lactone (AHL)?

A

its a hormone of bacteria and they produce more and more until quorum is reached, this is the certian density of cells to switch on transcription of genes, its the density of population

145
Q

what operon encodes bioluminescence?

A

lux operon

146
Q

what is quorum sensing present in?

A

likely archaea
some microbial eukaryotes

147
Q

what are examples of quorum sensing?

A

virulence factors
switching from free-living to growing as a biofilm

148
Q

what are the stages of biofilm formation?

A

increasing cell population
production of AHLs and c-di-GMP which leads to expolysaccharide production and flagella synthesis
attachment
mature biofilm

149
Q

what happens in biofilm formation?

A

produces polysaccharides that increase pathogenicity and antibiotic resistance
two quorum-sensing systems
produces AHLs and cyclic di-guanosine monophosphate (c-di-GMP)

150
Q

what does bioflim protect against?

A

everything, they are very strong and are produced by quorum sensing

151
Q

what is the typical soil bacteria size?

A

0.3 x 0.5um

152
Q

what is the typical marine bacteria size?

A

0.3 x 1 um

153
Q

what is the typical size of Escherichia coli?

A

1 x 3 um

154
Q

what are the exceptions to the tiny size of microbes?

A

Epulopiscium fishelsoni - 50 × 600 µm
Thiomargarita namibiensis - 750 µm

155
Q

what is the small cell size used to cope with in prokaryotes?

A

its a way to cope with low substrate availability, this increases the surface area to volumw ratio
substrate uptake is via cell membrane proteins
increasing surface area/ volume ratio improves the avalability to supply nutrients to the cytoplasmic volume

156
Q

what are various cell shapes of microbes and give examples of some?

A

Spherical (coccus) e.g. Micrococcus luteus
Rod (bacillus) e.g. Bacillus subtilis
Comma (spirilla) e.g. Vibrio cholera
Corkscrew (spirochetes) e.g. Borrelia burgdorferi
Appendaged e.g. Caulobacter crescentus
Filamentous e.g. some cyanobacteria

157
Q

what microbial habitats can microbes live in?

A

almost anywhere with water
temperature -10 to 121 degrees
pH 0-11
NaCl : 0 to 6M (~saturation)
others: oxygen, pressure and radiation

158
Q

what extremes can microbes live in?

A

extremes in temp, pH, salt, dessication, radiation and pressure

159
Q

why do microbes have diverse metabolic strategies?

A

because they’re usually competing with other microbes for resources/ survival

160
Q

what is a xerophile?

A

bacteria that can survive without much water

161
Q

what are psychrophile?

A

theyre microbes that can survive in extreme cold temperatures?

162
Q

what are thermophiles?

A

theyre microbes that can survive in extreme hot temperatures

163
Q

what are microbes called that can live in extremes of pH (theres different words for high and low pH)?

A

acidophils and alkaliphiles

164
Q

what are salt-loving microbes called?

A

halophiles

165
Q

what are bacteria that can survive in high NaCl conccentrations?

A

halotolerant

166
Q

what are microbes that live deep in the ocean who can survive high pressures called?

A

barophiles

167
Q

organisms can be facultive and obligate - what does that mean?

A

facultive- makes things easier for others
obligate - restricted to a particular function

168
Q

what are the three cardinal temperatures?

A

minimum
optimum
maximum

169
Q

what is involved in bateria comminuites with inter- and intra- species?

A

cell-cell signalling
community behaviour, division of labour, ‘altruism’
can have complex differentiation
metabolism
- because they are relatively small bacteria often work cooperatively to have an effect on their environment
they live in complex, changing environments

170
Q

what is mutualism?

A

its when the host benefits and the microbes benefit from their association

171
Q

what does pathogenesis mean?

A

the microbes cause harm to their host

172
Q

what does anabaena do?

A

they produce O2 and have a key role in the environment

173
Q

what do microbes need?

A

sufficient energy sources and anabolic raw materials - mainly C, N, S and P
you also need some ‘trace elements’- certian elements, metal ions and vitamins are used as enzyme co-factors
iron is extremely important for pathogenic bacteria
Fe is limiting in blood/ tissue becuase its bound
bacteria use sideophores to capture iron

174
Q

what are photophils?

A

photosynthetic - energy from sunlight

175
Q

what are chemotrophils?

A

energy from oxidation of chemicals
theyre sometimes distinguished as: chemo-litho-trophs which get energy from oxidation of inorganic chemicals hydrogen sulphide, sulpher, ammonia, nitrates, hydrogen gas or iron
chemo-organo-trophs which gets energy from oxidation of organic chemicals

176
Q

what are the two categories of organisms?

A

autotrophic- they make their own food
heterotrophic - food from other sources

177
Q

what are the two names for microbes that can and cannot fix CO2?

A

ones that can- autotrophs
ones that cant - heterotroph

178
Q

what is oligotrophy?

A

its the rule in nature
most of the biosphere has low availability of nutrients
olgiotrophy = small feeding and is growth at low nutrient concentrations

179
Q

what are photoautotrophs?

A

Cyanobacteria:
Use hydrogen atoms from water to reduce carbon dioxide to form carbohydrates
Produce oxygen gas (oxygenic process)
First organisms to conduct oxygenic photosynthesis (generated atmospheric O2)
Significant proportion of marine plankton (and marine microbial food web)

180
Q

what are lichens and what do they do?

A

Lichens: an association between two partners: an ascomycete (fungus) and a cyanobacterium
Cyanobacteria provide organic compounds via photosynthesis, and can fix nitrogen
Fungus provides protection, water retention, extracts minerals and nutrients from substrate
Sometimes a third partner (basidiomycetous yeast) – Spribille et al 2016

181
Q

what are chemoautototrophs?

A

they fix CO2 to make organic compounds, obtain energy from (usually inorganic) chemicals

182
Q

what happens in the nitrification in natural enviroments?

A

Central role in global nitrogen cycle
Loss of ammonia-based fertilisers
Nitrate pollution
N removal in wastewater treatment
Competition with primary producers for ammonia
Corrosion of buildings
Production of greenhouse gases
Biodegradation of organic pollutants

183
Q

what are photohetertrophs?

A

example - halobacteria
Halobacteria possess the protein Bacteriorhodopsin
Light energy is used to transfer protons across the membrane out of the cell.
The resulting proton gradient is used to
generate ATP
Gives Halobacteria their distinctive colour
Cannot fix CO2
Use organic carbon

184
Q

what are chemoheterotrophs?

A

Probably the most common nutritional mode
Uses organic (carbon) compounds for both carbon requirement and energy generation
Most bacterial pathogens are chemoheterotrophs

185
Q

what has more metabolic diversity- archaea and bacteria or eukaryotes?

A

archaea and bacteria

211 - microbiology (5 decks)

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