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Microbiology > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

Microbes make up what percent of the earths biomass?

A

around 60%

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2
Q

How many microbial species have been idetified?

A

less than 0.5% of around 2-4 billion

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3
Q

What microbes are acellular?

A

viruses and prions

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4
Q

What are prokaryotes microbes?

A

archaea and bacteria

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5
Q

What are eukaryotes microbes?

A

alae, fungi, protoza

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6
Q

What does the three-domain tree suggest?

A

eukaryotes are of archaeal origin

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7
Q

Why is the ring of life more representative?

A

eukaryotes have a mixed bacterial/archaeal lineages

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8
Q

How did eukaryotes arise?

A

when an archaeal host ingested a bacterium = mitochondria

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9
Q

What are the 4 characteristics of LUCA?

A

1) DNA as genetic material
2) Proteins and RNAs to catalyze essential processes needed to grow and reproduce
3) lipid membrane
4) lived in hydrothermal vents

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10
Q

How do we know where LUCA lived?

A

after isolating only the genes conserved between bacteria and archaea not shared by lateral gene transfer (355 genes). it was found that the function of these genes utilized hydrogen as an energy source and had reverse gyrase which is found in extremophiles.

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11
Q

Why can identifying LUCA help us identify life on other planets?

A

hydrothermal vents are common within our solar system

ex) icy moons like Europa and Enceladus have underground seas

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12
Q

What is the Taxonomic classification from most to least specific? eukarya

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

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13
Q

What is special about the taxonomic classification for prokaryotes

A

They have no kingdoms and that have a strain which is more specific than species

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14
Q

How do we classify prokaryotes

A

sequence variation in the 16S rRNA gene

The variable regions V1-V9 have high sequence divergence between species

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15
Q

What is the criteria for designating a new species?

A

a 16S rRNA gene sequence is less than 97% similar to another known species

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16
Q

Can most microbes be cultured in standard laboratory conditions?

A

nope

17
Q

What is an enterotube II?

A

can determine species via sample/culture reacting with 12 different growth mediums

18
Q

What is metagenomics?

A

can ID a species without culturing

it allow for sequencing of a gene

19
Q

What sequences all of the DNA in a sample?

A

shotgun metagenomics

20
Q

What is the largest of the prokaryotic domains?

A

bacteria

21
Q

What is the largest bacterial phylum?

A

proteobacteria (1,300 species)

22
Q

What is the ancestors of the modern chloroplasts?

A

cyanobacteria

23
Q

Where does the name cyanobacteria come from?

A

from the bluish pigment phycocyanin ( phyco = algae (not actually an algae) and cyanin = blue-green )

24
Q

How large are cyanobacteria?

A

very large (50 micron diameter

25
Q

What is special about Filamentous Nostoc?

A

can fix nitrogen to organic nitrogen is heterocysts (hets) cells —anaerobic environment

26
Q

Can nitrogen fixation occur in the presence of oxygen?

A

no

27
Q

What are the 6 classes of proteobacteria?

A

alpha, beta, gamma, delta, epsilon, zeta

28
Q

What are rhizobia?

A

alpha- proteobacteria that has a mutually beneficial relationship with leguminous plant. they fix atmospheric nitrogen. They invade root hair and form nodules on roots

29
Q

What is the special enzyme rhizobia have that allow it to convert N2 into ammonia? How much ATP is needed?

A

nitrogenase

needs 16 ATP

30
Q

What is gamma-proteobacterium enterohaemorrhagic E. coli (EHEC)?

A

bad and can be fatal bc it has a gene that encodes Shiga toxin severely damages the intestinal wall
—very very low infectious dose

31
Q

What is agrobacterium?

A

soil alpha-proterobacteria that invades dicot/broadleaf plant. Injects t-DNA that causes a tumor to develop which does not kill the plant.

Microbiology (17 decks)

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