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Infection Biology and Microbiology > Lecture 2: Microbial Evolution and Diversity > Flashcards

Lecture 2: Microbial Evolution and Diversity Flashcards

Friday 4th October 2024

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1
Q

How long ago did bacteria and archaea appear on the earth?

A

3.6 to 3.8 billion years ago

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2
Q

What is the surface origin hypothesis?

A
  • The idea that life evolved in warm little ponds on the surface of the planet, with a primordial soup of a mixture of chemicals that allowed organisms to form.
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3
Q

What protects us from UV radiation?

A

The ozone layer, which is made up of oxygen.

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4
Q

Why can early life be described as hostile?

A
  • There were high levels of UV radiation in the atmosphere.
  • There were many meteor strikes.
  • There was a lot of volcanic activity.
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5
Q

Why is the surface origin theory unlikely?

A

Because there were high levels of UV radiation, many meteor strikes, and high levels of volcanic activity.

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6
Q

What is the subsurface origin hypothesis?

A
  • The idea that life formed from hydrothermal vents in the ocean floor.
    (energy, heat, reduced compounds, organic compounds form)
  • More stable conditions than conditions on the surface
  • Constant source of energy, from reduced inorganic compounds produced inside the planet, which produce chemical energy).
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7
Q

Can life begin without light?

A

yes

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8
Q

What’s more stable RNA or DNA?

A

DNA

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9
Q

Can RNA act as an enzyme?

A

Yes, but DNA can’t

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10
Q

What was early life very dependant on?

A

H2 and CO2

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11
Q

What did H2 and CO2 react together in the early atmosphere to make?

A

Methane

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12
Q

Is it true that bacteria made acetate and archaea made methane in the early atmosphere?

A

Yes

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13
Q

As the planet began to cool, what was there a lesser reliance on?

A

There was a lesser reliance on chemical energy.

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14
Q

What did purple and green bacteria use for anoxygenic photosynthesis?

A

Hydrogen sulfide

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15
Q

When the cyanobacteria evolved, what did they use for photosynthesis?

A

Water, this produced Oxygen and Hydrogen

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16
Q

Initially, why was the oxygenation of the atmosphere problematic?

A

Because oxygen is highly reactive. So, the oxygen started oxidising everything it touched.

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17
Q

What happened as the amount of oxygen in the atmosphere increased?

A

An ozone layer was produced. This reduced the amount of UV light reaching the earth.

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18
Q

Is it true that before the use of molecular biology, we didn’t know that Archaea existed?

A

Yes

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19
Q

Describe the properties of marker molecules that are used in phylogenetic analysis

A
  • Must be universal
  • Must contain variable and conserved regions
  • Must not be subject to horizontal gene transfer
  • Must be truly homolgous
20
Q

Why are ribosomal RNA genes a universal molecular marker?

A

Because they’re present in all forms of life

21
Q

Name some molecular markers

A
  • Ribosomal RNA genes
  • ATPase subunits
  • EF-Tu
  • RecA
22
Q

Did the 3 domain tree of life arise due to comparative ribosomal RNA sequencing?

A

Yes

23
Q

Describe the first theory in the potential chain of events in the evolution of Eukaryotes

A
  • On the archaeal line before the eukarotes and archaea diverged from each other, a mitochondrion appeared.
  • The nucleus formed inside the eukarya.
  • A cyanobacteria entered a eukaryotic cell and became a chloroplast
24
Q

Describe the the more widely accepted theory in the potential chain of events in the evolution of Eukaryotes

A
  • A nucleus was created inside a eukaryotic cell.
  • The mitochondria appeared
  • The chloroplast appeared
25
Q

What is the alternative to the endosymbiont theory?

A

The hydrogen hypothesis

26
Q

What is the hydrogen hypothesis?

A

The idea that an archaea fused with a bacterial cell using Hydrogen as an energy source to produce hydrogen as a’waste’ product.

27
Q

what is the scientific name for Aquifex?

A

Aquifex aeolicus

28
Q

Describe aquifex

A
  • Is Isolated from a hot spring
  • Is Hyperthermophilic, so can grow in areas that are up to 90 degrees celcius.
  • One of the deepest branching bacterial phyla
  • Is a Chemolithoautotroph, so oxidises H2 to water using O2 as e- acceptor
  • Autotrophic: C-fixation
29
Q

What is the scientific name for Deinococcus?

A

Deinococcus radiodurans

30
Q

Describe Deinococcus

A
  • Extremely radiation resistant, including ionising radiation
  • Isolated from canned meat that was sterilised by gamma irradiation
  • Very rapidly reassembles radiation damaged DNA
  • Interest in using organism for bioremediation as it remaining viable in radiation contaminated sites
31
Q

Describe cynobacteria and plastids

A
  • Blue green algae
  • Plastids (chloroplasts in plants) were originally cyanobacteria
  • Morphologically diverse
  • Widely distributed
  • Oxygenic phototrophs, use light to fic carbon and release oxygen
  • Important in carbon cycle
  • May cause nuisance and toxic blooms
32
Q

describe Actinobacteria

A
  • They’re High GC Gram positives
  • They have varied morphology and varied metabolism
  • They’re heterotrophs, so use organic carbon as they’re energy source, so they eat food and don’t make their own food.

-

33
Q

Name an actinobacteria

A

Streptomycetes, which are major producers of antibiotics

34
Q

What are the pathogens of actinobacteria?

A

Mycobacterium leprae , which causes leprosy

M. tuberculosis, which causes tuberculosis

Corynebacterium diphteriae, which causes diptheria

35
Q

describe the firmicutes

A
  • Low G+C Gram positives
  • Mostly heterotrophs
  • Some form spores i.e Bacillus and Clostridium
  • Medically and industrially important
36
Q

what are the firmicutes Lactobacillus and Lactococcus are used in

A

food processing and probiotics

37
Q

what do the firmicutes Listeria and Staphylococcus cause?

A

Infections

38
Q

what firmicute causes botulism?

A

Clostridium botulinum

39
Q

what firmicute causes tetanus?

A

Clostridium tetani

40
Q

describe Chlamydia

A
  • All pathogens
  • Obligate intracellular parasites that live inside eukaryotic cells
  • C. trachomatis cause sexually transmitted disease, can lead to infertility
  • Also can infect the eye
41
Q

Describe Spirochaetes

A
  • Helically shaped, motile, gram negative
  • Unuusual flagellum, on inside of cell
  • Heterotrophs
  • Contains free living, symbiotic and parasitic species
  • Can cause syphilis and lyme disease
42
Q

Describe proteobacteria

A
  • Subdivided in alpha, beta, gamma, delta and epsilon Proteobacteria
  • Extremely metabolically diverse and include: Phototrophs, chemolithoautotrophs, heterotrophs
  • Include many important pathogens like Vibrio cholerae, which causes cholera and salmonella, which causes food poisoning.
43
Q

What are most archaea?

A

Methanogens

44
Q

Describe the methanogens

A
  • Produce methane as a waste product
  • Are at the very bottom of the food chain
  • Turn simple compounds into non-organic compounds, finish off the carbon cycle
  • Anaerobes
  • Grow slowly
  • Produce methane as a waste product
45
Q

Describe the halophilic archaea

A
  • grow in a saturated salt solution that is 20 times saltier than seawater
  • Salt lakes and ponds and salt crystals in subsurface
  • Can take very strange shapes and colours
  • Walsby square “bacterium”
46
Q
A

Infection Biology and Microbiology (23 decks)

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