Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cells 191 > Microbial Genetics > Flashcards

Microbial Genetics Flashcards

1
Q

what is generalised transduction?

A

when a piece of degraded host genome is put into a viral capsid instead of the virus genome. this takes a large chunk of genetic information to another cell and only occurs in the lytic cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is specialised / restricted transduction?

A

when virus takes a small piece of host DNA when it leaves the bacterial genome to form a loop in the cytoplasm. this is then passed on to other cells, and only occurs in the lysogenic cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is conjugation?

A

transfer of genetic information via plasmids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what organelle is used for conjugation?

A

pili

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what type of virulence factor is a plasmid?

A

fertility factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is an HFR cell?

A

a high frequency recombinant cell which has the plasmid bind into the host genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

why do HFR cells transfer so much genetic information?

A

the plasmid is bound into the host genome, so when it replicates the plasmid picks up a lot of host genetic information, which is then transferred to another bacterial cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the three symbiotic associations?

A

commensalism, mutualism, and parasitism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is mutualism?

A

when both species benefit eg humans and gut microbes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is commensalism?

A

when one species benefits and the other is not significantly affected eg humans and skin microbes (we benefit)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is parasitism

A

when one species benefits and the other one is harmed eg humans and opportunistic parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why are there exceptions to Koch’s postulates?

A
  • can’t be grown in pure culture
  • can’t deliberately infect a healthy person to test it
  • caused by multiple pathogens
  • caused by virulent strains of normal microbes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are some examples of exceptions to Koch’s postulates?

A
  • leprosy and siphilus, because neither can be grown in the lab and you can’t deliberately infect healthy people with them
  • liver cancer and peridontal disease are both caused by multiple pathogens. liver disease is caused by a combination of Hepatitis A and B
  • some E. coli strains are pathogenic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is pathogenicity?

A

the ability of a microbe to cause disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is virulence?

A

the ability to infect, spread disease, and be transmitted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are opportunistic pathogens?

A

microbes which are part of our normal microflora which can become virulent and cause disease under different conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what causes opportunistic microbes to become pathogenic?

A
  • immune system suppression (HIV, cancer, transplant therapy)
  • depletion of normal microbes from antimicrobial therapy
  • displacement of microbes to a different tissue within the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what type of toxins do gram negative bacteria release?

A

endotoxins / lipopolysaccharides which are embedded in the cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what type of toxins do gram positive bacteria release?

A

exotoxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the features of endotoxins?

A
  • poor antigens
  • heat stable
  • weak toxins
  • all have similar structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how are endotoxins released?

A
  • phagocytosis

- released from dead bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what do endotoxins cause?

A
  • fever

- inflammation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the features of exotoxins?

A
  • heat labile
  • potent toxins
  • varied structures
  • tissue specific
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are the two types of exotoxins?

A
  • neurotoxins

- cytotoxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what do exotoxins cause?

A
  • destroy any cells they come into contact with

- can kill

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

how are exotoxins released?

A

secreted from the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is selective toxicity?

A

targeting features of the pathogen which are different from the host cell so that the host is not harmed by the antibiotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what are some bacterial structures which are targeted by selective toxicity?

A
  • cell wall (targets peptidoglycan in bacteria)
  • cytoplasmic membrane (similar to host cell so is not ideal)
  • protein synthesis (bacterial ribosomes are different to eukaryote ribosomes)
  • metabolic processes (targets bacterial processes which humans dont use)
  • DNA / RNA synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what are the virulence factors of the cell?

A
  • adhesions
  • motility
  • siderophores
  • capsules
  • toxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

how do adhesions work?

A
  • physical adhesions work by fimbriae and pili binding to the host cell
  • chemical adhesions work by chemical reactions binding the bacteria to the host cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how is motility a virulence factor?

A

it allows the bacteria to move through mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what do siderophores do?

A

take up iron from the host to the pathogen, weakening the host and strengthening the bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

how does penicillin work?

A
  • active site is a lactum ring
  • binds to the penicillin binding protein in the cell wall
  • affects transpeptidase, an enzyme which links chains of peptidoglycan in the cell wall
  • enters through porins in the cell wall
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what effect on the bacterial cell does penicillin have?

A
  • cell wall degrades and becomes porous

- cell bursts from osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what techniques are used to create resistance to penicillin?

A
  • degradation of active site
  • change binding protein
  • change target enzyme
  • decreased uptake of penicillin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

how does degradation of the active site produce penicillin resistance?

A

the bacteria produces an enzyme which degrades the lactum ring on penicillin, meaning that the penicillin can’t work properly. makes the host allergic to penicillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

how does changing the target protein produce penicillin resistance?

A

mutating the penicillin binding protein means that penicillin can’t bind to it, and therefore can’t produce an antibiotic effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

how does changing the target enzyme produce penicillin resistance?

A

mutating the transpeptidase enzyme means that penicillin no longer has an effect on it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

how does decreased uptake produce penicillin resistance?

A

no longer making or altering porins restricts the amount of penicillin taken up by the cell, so reduces the effect it can have

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is an antibiotic?

A

a substance produced by one microorganism which is strongly antagonistic to other microbes in strong concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what are the three types of antibiotic?

A
  • bacteriocidal
  • bacteriolysic
  • bacteriostatic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what do bacteriostatic antibiotics do?

A
  • prevent the growth of bacteria
  • dont kill them
  • dont destroy their cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what do bacteriocidal antibiotics do?

A
  • kill bacteria

- dont destroy their cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what do bacteriolysic cells do?

A
  • kill bacteria

- destroy their cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what is a zone of inhibition?

A

a zone around an antibiotic on an agar plate where all the bacteria have been killed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

what does a small zone of inhibition indicate?

A

that the antibiotic is not very effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what does a large zone of inhibition indicate?

A

that the antibiotic is effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what is the minimal inhibitory concentration?

A

the smallest amount of antibiotic needed to kill the microbes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what amount of antibiotic is used in treatment?

A

four times more than the minimal inhibitory concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what do virulence factors assist in?

A
  • colonisation
  • invasion
  • growth
  • survival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

what is the best target of selective toxicity? why?

A

peptidoglycan in the cell wall, because only bacteria have this and it is not present in eukaryotes so there is no risk of the host cell being affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what is the worst target of selective toxicity? why?

A

cell membranes, because the eukaryote and prokaryote cell membranes are very similar so there is a significant risk that the host will also be affected by the antibiotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

how do you prevent antibiotic resistance?

A
  • test the sensitivity of the target antibiotic
  • use the correct antibiotic concentration
  • treat for long enough
  • complete the antibiotic regime
  • use multiple antibiotics for chronic infections
  • dont add antibiotics to animal food
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

how long should antibiotic treatment last for?

A

5 - 10 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

what should be considered when choosing antibiotics?

A
  • source of infection
  • site of infection
  • nature of the microbe (eg Gram positive or negative)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

how can antibiotics be administered?

A
  • topically (skin or eye)
  • suppository
  • orally
  • intravenously
  • intramuscular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what is the fastest way to administer antibiotics?

A

intravenously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

what is the slowest way to administer antibiotics?

A

intramuscularly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what are the possible infection sources?

A
  • nosocomal
  • animal reservoir
  • non-living reservoir (eg soil, water)
  • human carriers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

where are nosocomal infections contracted?

A

in healthcare facilities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Describe the properties of the bacterial genome

A
  • few duplicated genes
  • high number of genes compared to genome size
  • DNA loop in cytoplasm, not membrane bound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

How many genes do bacteria have?

A

200 - 800

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

what does a small bacterial genome indicate?

A

that the bacteria is a parasite, as it only needs the genes for survival in one constant environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

what does a large bacterial genome indicate?

A

that the bacteria lives in a range of environments, as it has the genes necessary to survive in many conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

what is vertical gene transfer?

A

when genes are passed on to off spring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

what is horizontal gene transfer?

A

transfer of genes between two organisms in the same generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

why are many mutations observed in bacteria?

A

because they reproduce so rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

what is transformation?

A

uptake of genetic information from the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

which experiment showed transformation?

A

Griffith’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

how is the rate of transformation increased?

A

electroporatation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

what is transduction?

A

transfer of genetic information via a bacteriophage vector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

how many people enter healthcare facilities with infections?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

how many people leave healthcare facilities with infections?

A

> 60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

what is an exogenous nosocomal infection?

A

an infection contracted from a nurse or doctor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

what is an endogenous nosocomal infection?

A

an infection created by opportunistic pathogens when microbes from the patients are moved to a different site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

what is an iatrogenic nosocomal infection?

A

when an infection is contracted as a result of medical treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

why do so many people get infections in hospitals?

A
  • accumulation of primary pathogens
  • accumulation of resistance microbes
  • microbes are highly virulent when leaving hosts
  • patients in hospital are more susceptible to infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

what are the five stages of infection?

A
  • incubation
  • prodromal period
  • illness
  • decline
  • convalascence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

describe the incubation period

A
  • no signs or symptoms

- low infectivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

what determines the length of the incubation period?

A
  • site of infection
  • immune defences
  • virulence of pathogen
  • characteristics of pathogen
  • dose of pathogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

describe the prodromal period

A
  • vague, general symptoms
  • not usually infections
  • short period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

describe the illness period

A
  • most severe signs and symptoms
  • most infectious
  • immune system has not yet developed specific defences
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

describe the decline period

A
  • declining signs / symptoms
  • immune response or medical intervention cause decrease in number of pathogens present
  • pathogen could be latent within host
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

describe the convalescence period

A
  • no signs or symptoms
  • tissues repaired
  • patient recovers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

describe the cycle of infection

A
  1. exposure to pathogen
  2. adhesion to skin or mucus
  3. invasion through epithelical cells
  4. colonisation and growth
    • production of virulence factors
  5. a) toxicity with local or systematic effects
    b) invasiveness with more growth at original and further sites
    • results in more exposure to pathogen
  6. tissue damage and disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

how can diseases be classified?

A
  • effected system
  • severity of infection
  • taxonomic group of pathogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

what are acute infections?

A

rapid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

what are chronic infections

A

slow and long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

what are sub-acute infections?

A

infections which allow opportunistic pathogens to cause infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

what are latent infections?

A

infections which have no effect on the patient but the pathogen is in their body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

what is the incidence rate?

A

the number of new cases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

what is the prevalence of a disease?

A

the total number of cases of the disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

what is an endemic disease?

A
  • always present in population

- low incidence rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

what is a sporadic disease?

A

-a few scattered cases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

what is an epidemic disease?

A
  • large number of cases within a set population

- small time frame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

what is a pandemic disease?

A

-widespread disease (continental / global)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

what causes seasonal incidence rates to peak?

A

animal vectors breeding / being more active at certain times of the year

98
Q

what experimental approaches are used in epidemiology?

A
  • reporting of clinical cases
  • diagnostic followups to confirm incidence
  • monitoring disease after therapy or vaccination
  • monitoring case history over decades
99
Q

what are the stages of microbial colony growth?

A
  • lag phase
  • exponential growth
  • stationary phase
  • decay
100
Q

what is the lag phase?

A

the time taken for the colony to become established

101
Q

what is the exponential phase?

A
  • unlimited division of cells
  • no limiting factors
  • population doubles over given time intervals
102
Q

what is the stationary phase?

A
  • colony stops reproducing

- cryptic growth observed

103
Q

what is the decline phase?

A

-growth limiting factors cause the viable count of the colony to decline

104
Q

what are growth limiting factors?

A
  • environmental conditions which limit the growth of cells
  • depletion of essential nutrients
  • accumulation of waste products
105
Q

what do bacteria need in order to grow in culture?

A
  • energy source
  • carbon source
  • reducing power
106
Q

why is an energy source needed?

A

organisms need a way to generate ATP because its needed for anabolic and catabolic reactions

107
Q

why is a carbon source needed?

A

it provides the precursor metabolites for organic building blocks, allowing for the formation of macromolecules

108
Q

why is a reducing power needed?

A

reducing powers (eg NADH and NADPH) are needed to power anabolic reactions and electron transport chains

they are especially important for photoautotrophs

109
Q

what is catabolism?

A

energy generation, occurs when complex molecules are broken down into building blocks
-produces energy for anabolism

110
Q

what is anabolism?

A

energy consumption, used when macromolecules are produced from monomers
-uses energy from catabolism

111
Q

what is an autotroph?

A

an organism which uses an inorganic carbon source

112
Q

what is a heterotroph?

A

an organism which organic carbon source

113
Q

what is a chemotroph?

A

an organism which gains energy from organic or inorganic chemical compounds.

114
Q

what is a phototroph?

A

an organism which gains energy from light

115
Q

what is a photoautotroph? (and examples)

A

organisms which gain energy from sunlight and have inorganic carbon sources

eg plants, algae, cynobacteria

116
Q

what is a photoheterotroph? (and examples)

A

organisms which gain energy from sunlight and have organic carbon sources

eg green and purple non-sulfur bacteria

117
Q

what is a chemoautotroph? (and examples)

A

gains energy from inorganic chemical sources (eg H2S) and has inorganic carbon sources

eg hydrogen, sulfur, and nitrifying bacteria

118
Q

what is a chemoheterotroph? (and examples)

A

organisms which gain energy from organic chemical sources (eg glucose) and has organic carbon sources

eg animals, bacteria, fungi, yeasts

119
Q

what social abilities do myxobacteria have?

A
  • social gliding motility (swarming)

- fruiting bodies

120
Q

how do myxobacteria swarm?

A

move forward or backwards by changing the polarity of the cell

121
Q

what does the P engine do?

A

pulls the myxobacteria along using pili

122
Q

what does the S engine do?

A

secretes slime for the myxobacteria to slide on

123
Q

how do myxobacteria kill other microbes?

A

they pool the colonies hydrolytic enzymes, lysing other microbial cells

124
Q

how do myxobacteria form fruiting bodies?

A
  • a multicellular action
  • aggregation formation towards the foci
  • forms a spore
125
Q

why do myxobacteria form fruiting bodies?

A

-survival mechanism against starvation

126
Q

what is microbial ecology?

A

the study of the interrelationships between microorganisms and their environment

127
Q

what is enrichment culture?

A

a culture which provides the specific temperature and chemical conditions needed to encourage groups of specific microbes. this replicates the specific environmental conditions needed for growth in a laboratory.

128
Q

what is a mesocosm?

A

an experimental system which simulates real life conditions as closely as possible, showing the interaction of the four trophic groups in microbial communities.

129
Q

what trophic group are colourless sulfur bacteria in?

A

chemoautotrophs

  • energy from H2S
  • carbon from CO2
130
Q

what trophic group are sulfate reducing bacteria?

A

chemoheterotrophs

  • energy and carbon source from acetate
  • acetate acts as reducing agent in anaerobic respiration
131
Q

what trophic group are coloured bacteria?

A

photoautotrophs

  • carbon from CO2
  • energy from photosynthesis
132
Q

how is acetate produced in a Winogradsky column?

A

acetate (which is needed by the sulfate reducing bacteria) is produced when sulfate reducing bacteria carry out fermentation of cellulose

133
Q

how is carbon dioxide produced in a Winogradsky column?

A

acetate is broken down into carbon dioxide. this also releases energy which the sulfate reducing bacteria use.

134
Q

what trophic group are cynobacteria?

A

photoautotrophs

  • energy from photosynthesis
  • inorganic carbon source
135
Q

what is the order of trophic groups in Winogradsky columns?

A
  • photoautotrophs
  • chemoautotrophs
  • photoautotrophs
  • chemoheterotrophs
136
Q

what is the order of microbes in Winogradsky columns?

A
  • cynobacteria
  • colorless sulfur bacteria
  • purple sulfur bacteria
  • green sulfur bacteria
  • sulfate reducing bacteria
  • cellulose degrading bacteria
137
Q

what is the energy source gradient in Winogradsky columns?

A

sunlight (photoautotrophs)
->
chemicals (chemoautotrophs)

138
Q

what is the sulfide gradient in Winogradsky columns?

A

low -> high

139
Q

what is the oxygen gradient in Winogradsky columns?

A

high -> low

140
Q

what is the reducing agent of cynobacteria?

A

H2O being oxidised to form O2

141
Q

what is the reducing agent of colourless sulfur bacteria?

A

H2S being oxidised to form SO4

142
Q

what is the reducing agent of coloured bacteria?

A

H2S being oxidised to form S

143
Q

what is the reducing agent of sulfate reducing bacteria?

A

SO4(2-) being oxidised to form H2S

144
Q

what is the reducing agent of cellulose degrading bacteria?

A

cellulose being reduced to form lactate and other organic acids

145
Q

what type of respiration do coloured bacteria do?

A

anoxygenic photosynthesis

146
Q

what type of respiration do cynobacteria do?

A

oxygenic photosynthesis

147
Q

what type of respiration do cellulose degrading bacteria do?

A

fermentation

148
Q

how does anoxygenic photosynthesis work?

A
  • H2S is oxidised, transferring electrons to NADP+ to produce NADPH
  • NADPH reduces back to NADP+, donating an electron to CO2 so that is can form an organic molecule
149
Q

how does cyclic phosphorylation work?

A
  • an electron is excited by light, going from +0.5V to -1.0V
  • the electron flows down the electron transport chain, generating ATP
  • the same electron is reduced again, forming a cycle
150
Q

how is non-cyclic phosphorylation different to cyclic phosphorylation?

A
  • in cyclic phosphorylation the same electron is used over and over again
  • in non-cyclic phosphorylation the electron is removed from the complex and replaced by the splitting of a water molecule
151
Q

how do microbes in Winogradsky columns coexist while competing for light?

A

each species absorbs a different wavelength of light

152
Q

what do cynobacteria use to capture light energy?

A

chlorophyll A

153
Q

what do green and purple bacteria use to capture light energy?

A

bacteriochlorophyll

154
Q

what wavelengths of light do cynobacteria absorb?

A

500 - 550nm

155
Q

what wavelengths of light do algae absorb?

A

500 - 550nm

156
Q

what wavelengths of light do purple bacteria absorb?

A

> 800 nm

157
Q

what wavelengths of light do green bacteria absorb?

A

550 - 850nm

158
Q

what is produced in the decomposition of organic material?

A
  • humus
  • CO2
  • CH4
159
Q

what is the biochemical oxygen demand a measure of?

A

the cleanliness of water

160
Q

what does the BOD measure?

A

the relative amount of dissolved oxygen consumed by microbes while aerobically decomposing organic and inorganic material in the water sample

161
Q

what occurs in aerobic decomposition?

A

organic pollutants are oxidised to CO2. this process requires oxygen

162
Q

why does polluted water have a higher BOD than clean water?

A

there are more materials in the water needing to be broken down, so more oxygen is required to aerobically decompose them

163
Q

what is a dead zone?

A

an area where the oxygen concentration is too low for organisms to survive. this is called environmental hypoxia

164
Q

why do dead zones occur?

A

bacteria decompose massive amounts of material in the water, causing all the oxygen in the area to be converted to carbon dioxide

165
Q

what is an example of a dead zone?

A

The Gulf of Mexico

166
Q

how did the Gulf of Mexico become a dead zone?

A
  • Missisippi river carried industrial run off and fertiliser to the ocean
  • caused massive algal blooms because of the large amounts of nitrogen and carbon
  • the algae died and was decomposed, using all the oxygen in the area
167
Q

what is a coliform?

A

a bacterial indicator of the sanitary quality of food and water. it indicates when pathogens from faeces are present

168
Q

what is primary treatment?

A

physical process

169
Q

what occurs in screening? (primary treatment)

A

screening of waste water is the first step in primary treatment. this removes indestructible objects from the water so that they can be destroyed

170
Q

what occurs in the sedimentation tank? (primary treatment)

A

wastewater is sent to the sedimentation tank after screening. this separates it into sludge and liquid.

171
Q

what happens to the sludge after the sedimentation tank? (primary treatment)

A

incinerated

172
Q

what happens to the liquid after the sedimentation tank? (primary treatment)

A
  • sent for marine disposal

- may also be treated by UV or chlorination to reduce the number of pathogens

173
Q

what is secondary treatment?

A

biological process

174
Q

what is used in secondary treatment?

A

indigenous, water bourne microbes

175
Q

what occurs in the aeration tank? (secondary treatment)

A
  • microbes convert organic materials to carbon dioxide

- oxygen is pumped through to ensure that this can occur

176
Q

what occurs in the settling tank? (secondary treatment)

A
  • clear effluent (very low BOD) leaves the tank
  • flocs settle into an activated sludge
  • flocs are either returned to the aeration tank (replenishing the microbes) or go to anoxic sludge digestion
177
Q

what is tertiary treatment?

A

anything which occurs after primary and secondary treatments

178
Q

what are some examples of tertiary treatments?

A
  • filtration
  • UV
  • chloride disinfectant
  • anoxic sludge digestion
179
Q

what occurs in anoxic sludge digestion?

A
  • anoxic anaerobes break down complex polymers in sludge via fermentation
  • very slow processes
  • produces organic acids eg lactic acid and methane
180
Q

what are raw materials which can be used to produce biofuels?

A
  • starch
  • sucrose
  • cellulose
181
Q

what are the steps in biofuel production?

A

raw materials -> solubilise and hydrolyse -> fermentation -> distillation -> biofuels

182
Q

what is used to carry out fermentation?

A
  • bacteria

- yeasts

183
Q

what three things are needed to produce enough raw materials for biofuel production?

A
  • vast landmass
  • cheap labour
  • favourable climate
184
Q

which two gases can be used to produce biofuels?

A
  • carbon dioxide

- carbon monoxide

185
Q

what can synthetic microbes be used for?

A
  • optimise biofuel production
  • produce food
  • produce antibiotics
  • degrade pollutants eg DDT
186
Q

what is the human microbiome project?

A

a strategy to understand the microbial composition of humans in regards to metabolism and disease

187
Q

what is a microbiome?

A

the complete collection of genes in the genomes of all bacterial species which have evolved with the human host

188
Q

what is the microbiota?

A

individual bacterial species within the biome

189
Q

what are the four most common bacterial phyla in humans?

A
  • firmicutes
  • bacteroidetes
  • proteobacteria
  • actinobacteria
190
Q

what is the most common bacterial genus in the human gastrointestinal tract?

A

Bifidobacterium, from the actinobacteria phylum

191
Q

describe the environment of the gastrointestinal tract

A
  • anaerobic
  • constant environment
  • acidic pH in stomach, gets more neutral lower down
192
Q

what can destabilise human gut microbes?

A

broad spectrum antibiotics

193
Q

when is the adult microbiome established?

A

in the weaning stage

194
Q

how do gut microbes benefit us?

A
  • break down toxins, carcinogens, and xerobiotics
  • synthesise micronutrients such as vitamins
  • ferment indigestible food into short chain fatty acids
  • protect us from pathogens
195
Q

what is an Archaean gut microbe?

A

Methanobrevibactor smithii, from the Euryarchareota phylum

196
Q

how are obese state gut microbes different to lean state gut microbes?

A
  • harvest more energy
  • 50% more firmicutes
  • 50% less bacteroidetes
  • more Methanobrevibacter
197
Q

describe the mouse obesity experiment

A
  • germ free and conventional mice were both fed a Western diet
  • germ free mice gained less weight even though they ate more
  • microbe transplant occured
  • germ free mouse + conventional microbes = mouse got fat
  • germ free mouse + germ free microbes = mouse stayed lean
198
Q

what did the mouse obesity experiment show?

A
  • obesity is transferable

- obese state microbes have increased fermentation ability

199
Q

what is a functional food?

A

a food which claims to have a health promoting or disease preventing benefit beyond supplying nutrients

200
Q

what are probiotics?

A

food which contain live microbes which give a benefit to the host

201
Q

what is an example of probiotics?

A

-yogurt which contains a strain of Bifideobacteria infantis which helps irritable bowel syndrome

202
Q

what are two common microbes in probiotics?

A
  • lactic acid bacteria

- Bifideobacteria

203
Q

what is a requirement of microbes in probiotics?

A

must be able to survive through the stomach to colonise the gut

204
Q

what are prebiotics?

A

specialised plant fibres which beneficially nourish the good bacteria in the large intestine. they are not digested by the body, so can act as fertiliser for the bacteria

205
Q

what are some examples of ruminants?

A

cows, goats, sheep

-animals which have a rumen stomach

206
Q

what are rumen microbes?

A

microbes which live in rumen stomachs

207
Q

what is the relationship between rumens and ruminants?

A

they have a mutually dependant, symbiotic relationship

208
Q

what are the four parts of the ruminant stomach?

A
  • rumen
  • reticulum
  • omasum
  • abomsum
209
Q

how are the first three parts of the rumen stomach different to the last part?

A
  • the first three chambers don’t secrete any acid, digestive enzymes, or mucus so all digestion of cellulosic material is done by microbes
  • the fourth chamber is the only “true” acidic stomach
210
Q

what occurs in the rumen?

A

food is churned for 9 - 12 hours in a rotary mation while rumen microbes break down cellulose structures

211
Q

what occurs in the reticulum?

A

food is regurgitated and re-chewed (chewing the cud) to increase the surface area of the food, increasing the rate of bacterial digestion

212
Q

what happens in the omasum?

A
  • partially digested food is filtered

- regulates what enters the abomasum

213
Q

what happens in the abomasum?

A
  • denatures protein
  • digests gastric juices
  • site of bacterial protein assimilation, allowing the ruminant to gain protein and vitamins from dead microbes
214
Q

what are the features of the rumen?

A
  • large surface area = can hold more food for microbial fermentation
  • 39 degrees, 6.5 pH = constant environment which selects for specialised bacteria
215
Q

how is a balanced pH maintained?

A

carbonate from ruminant saliva offsets acid produced by bacterial fermentation

216
Q

what is a syntrophic relationship?

A
  • when one species lives off the waste products of another species
  • a relationship which makes a reaction possible which is not energetically possible with only one species present
217
Q

how is the rumen microbes an example of a syntrophic relationship?

A

there is crossfeeding of nutrients and end products, so one species lives off the waste products of another species

218
Q

what are examples of cellulose degraders?

A
  • Fiberobacter succinogenes

- Ruminococcus albus

219
Q

what are examples of starch degraders?

A
  • Bacteroides ruminocola

- Streptococcus bovis

220
Q

what are examples of lactase degraders?

A

Megasphaera elsdenii

221
Q

what is an example of a methanogen?

A

Methanobrevibactor rumniantium

222
Q

what is cellulosis?

A

hydrolysis of cellulose

223
Q

what is amylosis?

A

hydrolysis of starch

224
Q

what occurs during rumen fermentation?

A

cellulose, starch, and sugars are hydrolysed and fermented. this produces short chain fatty acids, carbon dioxide, and methane

225
Q

what are three types of short chain fatty acids produced during rumen fermentation?

A
  • acetic acid
  • propanoic acid
  • butric acid

these acids act as a carbon source and an energy source for the ruminant

226
Q

how do ruminants benefit from their relationship with rumen microbes?

A
  • plant structures eg cellulose are broken down, giving the ruminant an additional energy and carbon source. they can’t do this because they don’t have the enzymes.
  • get protein and vitamins from assimilation of dead microbes in the abomasum
227
Q

how do rumen microbes benefit from their relationship with ruminants?

A
  • constant food supply
  • constant environment
  • space to live
228
Q

what is an example of a syntrophic relationship between rumen microbes?

A

interspecies hydrogen transfer

229
Q

what produces hydrogen in the rumen?

A

Ruminococcus albus

230
Q

what uses hydrogen in the rumen?

A

methanogens eg Methanobrevibacter rumniantium

231
Q

how does Ruminococcus albus produce hydrogen?

A
  • oxidises glucose to pyruvate

- hydrogen is side product

232
Q

why must hydrogen concentration in the rumen be kept balanced?

A

lactase forms if hydrogen is added to pyruvate. when concentration of lactase is too high fermentation stops

233
Q

what do methanogens use hydrogen for?

A

use as an electron donor to convert carbon dioxide to methane

234
Q

why are methanogens important to the rumen?

A

keeping hydrogen levels balanced so that fermentation remains directed towards acetate, not lactate or acetate.

235
Q

how efficitant is methane at trapping greenhouse gasses?

A

21 times more efficient than carbon dioxide

236
Q

how much have methane levels risen since 1750?

A

148% increase

237
Q

how much have carbon dioxide levels risen since 1750?

A

36% increase

238
Q

what must we do to our food production in order to keep up with demand?

A

double it in the next 30 years

239
Q

how much does agriculture contribute to NZ’s greenhouse gas emissions?

A

50%

240
Q

which gases make up agricultural greenhouse gas emissions?

A
  • nitrous oxide = 16%
  • methane = 32%
  • carbon dioxide is absorbed by grass so it does not accumulate in the atmosphere as much
241
Q

what does the Kyoto pledge state?

A

that NZ will lower greenhouse gas emissions back to 1990 levels and pay a tax based on how much we exceed this by

242
Q

what are four strategies to reduce methane production by ruminants?

A
  • different microbes absorb methane produced by rumen microbes
  • feeding ruminants a different diet
  • controlling growth of methanogens so that the least possible amount of methane is produced
  • researching wallaby gut microbes as they emit very little methane compared to other ruminants

Cells 191 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions