Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Michaelmas Term 1 > The Social Microbe > Flashcards

The Social Microbe Flashcards

(78 cards)

Start Studying
1
Q

What is LUCA?

A

An inferred cellular organism

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

Where does the inference for LUCA arise from?

A

The shared fundamental biochemical and genetic characteristics of all known life

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

LUCA hypotheses

A
  • anaerobic
  • CO2-fixing
  • H2-dependent
  • N2-fixing
  • thermophilic
  • dependent on transition metals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What setting are the LUCA hypotheses consistent with?

A

Hydrothermal

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

What are the competing hypothesis for the origin of life location:

A
  • surface origin hypothesis
  • subsurface origin hypothesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Madigan model for the origin of cellular life

A
  • RNA World
  • DNA becomes genetic repository; RNA adopts a more transitory role in genetic inheritance
  • three part system (DNA, RNA, protein) evolve and become universal amoung cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the RNA World theory?

A

That the first self-replicating systems must have been RNA-based

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

What would make RNA a good first self-replicator?

A
  • can bind small molecules (ATP, other nucleotides)
  • catalytic activity (autocatalysis?)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the world in which life arose

A
  • hot
  • anoxic
  • inorganic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How did the origin of life change the earth?

A
  • organic chemical synthesis
  • CO2 fixation
  • oxygenic photosynthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What did oxygenic photosynthesis facilitate?

A
  • O2-based respiration
  • much more energy available
  • evolution of super-energy expensive lifestyles (large, multicellular)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the evolution of oxygenic photosynthesis

A

~2.7GYA cyanobacteria evolved a photosystem using H2O rather than H2S

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can we measure O2?

A
  • it reacts spontaneously with oceanic iron minerals
  • abundant iron oxides visible in geological record (banded iron formations)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What did O2 accumulation in the atmosphere result in?

A
  • formation of the ozone shield
  • toxic oxygen radicals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the endosymbiosis eukaryogenesis theory

A

mitochondrion of present-day eukaryotes arose from the stable incorporation of an aerobic bacteria into early eukaryotic cells

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

What did endosymbiosis allow?

A

increased early cell’s respiratory capacity, allowing early mitochondria-containing cells with o becomes the ancestors of all extant Euakarya

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

Describe chloroplast endosymbiosis

A
  • stable incorporation of a Cyanobacterium-like cell into the cytoplasm of a eukaryotic lineage
  • plant evolution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is common between prokaryotes, mitochondria and chloroplasts relative to size and shape

A
  • smaller
  • similar in size and shape
  • generally lack membrane bound organelles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is common between prokaryotes, mitochondria and chloroplasts relative to ribosomes

A
  • smallest
  • 60S-75S
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is common between prokaryotes, mitochondria and chloroplasts relative to the initiation of protein synthesis

A
  • initiation amino is N-formyl-methionine (not methionine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is common between prokaryotes, mitochondria and chloroplasts relative to chromosome

A

Mostly circular, not linear

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

What is common between prokaryotes, mitochondria and chloroplasts relative to rifampicin action

A

Inhibits RNA polymerase (does not in eukaryotes)

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

Rifampicin

A

Ah inhibitor of RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is common between prokaryotes, mitochondria and chloroplasts relative to chloramphenicol

A

Inhibits protein synthesis (doesn’t in eukaryotes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Chloramphenicol
Protein synthesis inhibitor
26
What about mitochondria and chloroplast are consistent with the endosymbiotic hypothesis
Their physiology, metabolism and genome structure
27
Compare and contrast mitochondria and chloroplasts relative to their function
Mitochondrion: oxidative phosphorylation, beta oxidation and photorespiration Chloroplast: photosynthesis and photorespiration
28
Compare and contrast mitochondria and chloroplasts relative to their metabolism
Mitochondria: break down glucose to CO2 and H2O, consumes oxygen, generates ATP Chloroplasts: synthesise glucose from CO2 and H2O, libérâtes oxygen
29
Compare and contrast mitochondria and chloroplasts relative to their shape
Mitochondria: oblong or bean shaped Chloroplast: ellipsoid disc
30
Compare and contrast mitochondria and chloroplasts relative to their structure
Mitochondria: double membrane; inner membrane folded into cristae Chloroplast: double membrane; inner membrane contains thylakoid stacks, grams
31
Compare and contrast mitochondria and chloroplasts relative to their size
Mitochondria: 0.75-3 micromètres Chloroplasts: 0.5-10 micromètres x 2.5 micromètres
32
Compare and contrast mitochondria and chloroplasts relative to their distribution
Mitochondria: universal, most eukaryotes Chloroplasts: restricted; plants, green algae, some unicellular eukaryotes
33
Compare mitochondria and chloroplasts
- both have small circular genomes - both replicate independently of the rest of the cell - in both the outer membrane has proteins that enable permeability - in both the inner semi-permeable membrane is the site of metabolic activity
34
Mitochondria late scenario
- Posits endosymbiosis uptake by phagocytosis - requires evolution of phagocytosis first
35
Mitochondria early hydrogen hypothesis
- metabolic symbiosis of a methane producing bacterium - complex membrane structures and molecules and phagocytosis evolve after endosymbiosis
36
Both mitochondria late and mitochondria early envisage
- extensive gene transfer from bacterium to host - system evolution is to transfer nuclear-encoded proteins to organelle
37
Syntrophic communities
- cross-feeding - one species lives off of the products of another species - highly nutritional, interdependent communities of eubacteria and archaea - anoxic environments
38
Describe gene exchange in syntrophic communities
- patterns - suggests community above independent evolution
39
Relationship between mitochondria early hypothesis and syntrophy
- eukaryogenesis from bacterial and archaea syntrophic interactions - supported by chimeric eukaryotic genomes
40
Examples of intracellular bacteria
1. Pleurocapsa spp 2. Pseudomonas fluorescens, Bdellovibrio bacteriovorus 3. Pseudococcidae
41
Describe Pleurocapsa spp.
Nitrogen-fixing, spore-forming marine cyanobacterium showing intracellular bacteria
42
Describe Pseudomonas fluorescens and Bdellovibrio bacteriovorus
Bdellovibrio bacteriovorus infects Pseudomonas fluorescens periplasm
43
Describe mealybug Pseudococcidae
- TEM shows bacteriome containing betaproteobacterial Trembleya endosymbionts
44
Describe Trembleya symbionts
Contain gammaproteobacterial Morganella endosymbionts
45
What are Acanthamoeba?
Ubiquitous, free-living amoebae
46
Describe Acanthamoeba:
- important predators of microbial communities - ~25% contain obligate intracellular bacterial symbionts
47
Which two endosymbionts are present in one Acanthamoeba?
- Candidatus procabacter - Candidatus parachlamydia
48
Where are mitosomes found?
In some unicellular anaerobic/micro aerophilic eukaryotes
49
Give a genus in which mitosomes are found
- Giardia - parasitic diplomondad
50
Describe mitosomes
- double membrane - lack DNA - reduced metabolic capacity (no ECT/TCA enzymes)
51
What are hydrogenosomes?
Energy-yielding mitochondria alternatives present in some anaerobic protists
52
Give an example of a species containing hydrogenosomes
- Nyctotherus ovalis - ciliate
53
Where are hydrogenosomes found?
- trichomonads - hypermastigotes - euglenids
54
What are hydrogenosomes thought to have evolved from?
Mitochondria
55
Describe hydrogenosomes
- double membrane - DNA present (reduced due to gene loss)
56
How do hydrogenosomes generate energy?
- Partial oxidation of pyruvate to acetate - pyruvate fermentation
57
Give an example of a genus that exists without mitochondria
Monocercomonoides
58
Describe the amitochondrial status of Monocercomonoides
- Thought that they once had them, but we’re lost over time - evidence of LGT of bacterial sulfur mobilisation genes
59
Give an example of primary endosymbiosis
Uptake of a Cyanobacteria by a non-photosynthetic organism
60
Give an example of secondary endosymbiosis
Plastid-containing algae ingested by non-photosynthetic eukaryote
61
Describe diatoms
- abundant microscopic algae - contribute ~20% to global photosynthesis - important in biogeochemical cycles
62
What are diatoms predominantly associated with?
- proteobacteria - bacteriodetes
63
How have bacteria contributed to diatom genomes?
- through HGT - recruitment of metabolic capacity
64
What are the metabolic interactions of diatoms?
- parasitism - synergism - competition
65
Describe the Asgard superphylum lineage
Thought to be ancestral to, or sister group of, Eukarya
66
All cellular life has a
Common ancestor
67
The first metabolic processes arose in an
Oxygen-free, microbial world
68
How did eukaryotes aquire during endosymbiosis?
Nutritional versatility and oxygen-based metabolism
69
What did gene exchange post-endosymbiosis result in
Increasing interdependence
70
OILRIG
- oxygen is the most oxidising agent - hydrogen is the most reducing agent
71
Oxygen =
Toxic
72
H2O is a
Much more efficient energy system than H2S
73
Eukaryotes can
Compartmentalise
74
LGT occurs from
Organelle to nucleus
75
HGT occurs from
Bacteria to eukaryote
76
Diatomic carbons in the sea are not
Locked up
77
Most eukaryotes are still
Microbes
78
List some mitochondria-related entities
- mitosomes - hydrogenosomes

Michaelmas Term 1 (42 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions