positive bioassociations of microbes

Question 1

what are the two types of symbiote transmission

Answer 1

vertical transmission
horizontal transmission
(can be mixed)

Question 2

how does symbiosis develop

Answer 2

through the prolonged association and coevolution between two partners

Question 3

phylosymbiosis def

Answer 3

a microbial community that recapitulates the phylogeny of the host

Question 4

what happens to the genome of a microorganism in symbiosis with a higher organism

Answer 4

the genome shrinks as the microbe can get plenty of biomolecules from its host, so it won’t need to synthesise them for itself.

Question 5

why is a smaller genome more beneficial

Answer 5

a smaller genome requires less resources and energy to replicate.

Question 6

how to symbiotes attach to their hosts

Answer 6

they could insert effector proteins to allow the microbe entry.
Once inside the host the microbe will secrete biomolecules to prevent the hosts immune system from attacking it

Question 7

How is the Hawaiian bobtail squid an example of symbiosis

Answer 7

-symbiosis with A.fisceri
-bioluminescent bacteria desguises the squid as moonlight from above or below
-transmission is horizontal since the squid isn’t born with the bacteria
-the light organ of the squid is specifically colonised within 6 hours

Question 8

what is Quorum sensing

Answer 8

a method of cell to cell communication used to coordinate gene expression and communal behaviour
widely employed
achieved by the release and detection of autoinducers
a larger colony means a greater concentration of autoinducers allowing the colony to sense how large it is

Question 9

what can quorum sensing control

Answer 9

sporulation
bioluminescence
virulence
biofilm formation

Question 10

how are marine sponges an example of symbiosis

Answer 10

vertical transmission from parents
can be very dependant or very independent from microbes.
the microbes metabolise nitrogen and essential vitamins
some microbes produce compounds that deter predators
the bacteria eat organics from water whilst the sponge then eats the bacteria

Question 11

what is wolbachia

Answer 11

a group of symbiotic bacteria that is incredibly widespread in insects
vertical transmission
manipulates host reproduction, infected females are favoured over uninfected ones

Question 12

how is wolbachia used to control mosquitoes

Answer 12

when infected males mate with uninfected females they produce unviable offspring.
This can be used in lab raised bacteria to outcompete and eliminate wild populations that may carry disease

Question 13

what are the characteristics of the rumen

Answer 13

anaerobic
contains microbes that break down plant fibre
produces strong greenhouse gasses like methane

Question 14

what is the composition of the rumen microbiome

Answer 14

composed of bacteria, protists, archea and fungi

Question 15

what are Fermicutes and Bacteriodetes

Answer 15

the cellulose degrading bacteria found in the rumen

Question 16

what is luciferin and luciferase

Answer 16

luciferin is a molecule that reacts with oxygen to create light. this is seen in most bioluminescent organisms. This reaction is catalysed by luciferase.

Question 17

What is a luciferase assay

Answer 17

we can use luciferase as a reporter gene and add the gene that codes for luciferase into the genome, before other genes we want to study.
we can then measure gene expression by the amount of light produced

Question 18

Explain the anaerobic food web that takes place in the rumen

Answer 18

-a few bacterial species break down plant fibre and turn it into sugars
-other bacteria can then ferment the sugars into volatile fatty acids
-finally methanogenic bacteria turn H2 along with specific fermentation products into methane

Question 19

what are VFAs

Answer 19

Volatile Fatty Acids. These are used as a food source for the rumen mammal.
VFAs make up 70% of the animals cellular energy requirement

Question 20

what are the 3 main groups of microbes in the human gut

Answer 20

Bacteriodetes
Firmicutes
Proteobacteria

Question 21

explain the gut brain axis

Answer 21

The idea that the host can influence its microbes and vice versa. The host and microbes communicate through metabolites, hormones and neurotransmitters

Question 22

what are the main benefits of microbes for plants

Answer 22

-nitrogen fixation
-converting essential elements into forms plants can access
-producing plant hormones like auxins
-protect against pathogens

Question 23

what are nitrogenases

Answer 23

enzymes found in rhizobia bacteria found in the root nodules of legumes. They convert N2 to NH3 in microaerophilic environments (low oxygen).