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Biology 1020 > Bacteria and Archaea > Flashcards

Bacteria and Archaea Flashcards

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1
Q

What are prokaryotes?

A

– ancient organisms
– ubiquitous [occur/thrive almost everywhere including extreme habitats]
– successful [due to structural, functional and genetic adaptation]
– have simple internal organization [no nucleus, no membrane-bound organelles]
– Classified into two domains [based on structure, physiology and bio chemistry]

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2
Q

What are the three domains of the tree of life?

A

1.bacteria
2.archaea
3.eukaryotes
3, 500 million years ago oldest prokaryotic fossil

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3
Q

Why are prokaryotes much smaller than average eucaryotic protists, plant or animal cells?

A

Surface area: volume ratio

  • limits size that functional cells can attain
  • prokaryotic cell design reached its size limit
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4
Q

Prokaryotes are morphologically what? But metabolically what?

A

Prokaryotes are morphologically simple but metabolically diverse playing a key role in the cycling of matter on earth [global carbon cycle/global nitrogen cycle]

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5
Q

Internal cell structure of bacteria

A

– Cytoplasm
– internal membranes [specialized]
– genome organization [nucleoid region/plasmids]
– ribosomes

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6
Q

External cell structure of bacteria

A 
– Plasma membrane 
– cell wall 
– flagella 
– capsule 
– Pili
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7
Q

What is peptidoglycan?

A

Cell walls contain peptidoglycan – polymer of modified sugars cross-link by short polypeptides [cell walls of Archaea lack peptidoglycan]

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8
Q

Gram positive structure

A 
Cell wall (peptidoglycan layer)
Plasma membrane
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9
Q

Gram negative structure

A 
Lipopolysaccharide
Cell wall (outer membrane then peptidoglycan layer)
Plasma membrane
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10
Q

Lipopolysaccharides on walls of gram negative bacteria are often…
This means that outer membrane of gram negative bacteria are…

A

Toxic
Antibiotic resistant
Many antibiotics inhibit the synthesis of cross-links in peptidoglycan in inner membranes

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11
Q

What is bacteria?

A

– Unicellular
– have simple shapes (sphere [ coccus], rod [bacillus], helix [spirillus])
- are very small [have diameter in range of 1 to 10 µm]

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12
Q

How is bacterial cell diversity generated?

A

Bacteria have some additional unique processes that and genetic diversity – collectively referred to as horizontal gene transfer

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13
Q

List the 3 types of horizontal gene transfer

A
  1. Conjugation
  2. Transformation
  3. Transduction (viruses)
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14
Q

Why are bacterial genomes smaller than those of eukaryotes?

A

Bacterial genomes lack non-coding stretches of DNA compared to eukaryotes
diversity in prokaryotes due to mutations and vertical gene transfer from parent cells to daughter cells [mitosis]

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15
Q

Define Conjucation

A

And conjugation, DNA [usually a plasmid] from a donor cell is transferred through a pilus [strands of cytoplasm] into the recipient cell
Spreads novel jeans and bacterial population [example: antibiotic resistance]
plasmids used in genetic engineering techniques [GMO]
Direct contact (cell-cell)

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16
Q

Define Transformation

A

In transformation DNA released into the environment by dead cells and cell breakdown is taken up by a recipient cell
genes can be transferred from cell to cell without direct contact

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17
Q

Define transduction

A

In transduction DNA is transferred from a donor to a recipient cell by a virus
common in nature and as a technique in research labs [genetic engineering]
no direct contact (cell – virus – cell)

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18
Q

Metabolic roles of prokaryotes: list 4 biogeochemical cycles they are involved in

A
  1. carbon
  2. oxygen
  3. sulfur
  4. nitrogen
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19
Q

Role in carbon cycling linked to oxygen cycling

A

Evolution of oxygenic photosynthesis by Cyanobacteria - key to O2 accumulation in atmosphere

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20
Q 
Major nutritional modes: Autotrophs 
Name nutritional mode 
Name energy source
Name carbon source
List types of organisms
A

Photoautotroph
Light
CO2
Photosynthetic prokaryotes (Cyanobacteria), plants, certain protists (algae)

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21
Q 
Major nutritional modes: Autotrophs 
Name nutritional mode
Name energy source
Name carbon source
List types of organisms
A

Chemoautotroph
Inorganic chemicals
CO2
Certain prokaryotes (ex. Sulfolobus)

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22
Q 
Major nutritional modes: Heterotrophs 
Name nutritional mode
Name energy source
Name carbon source
List types of organisms
A

Photoheterotroph
Light
Organic compounds
Certain prokaryotes

23
Q 
Major nutritional modes: Heterotrophs 
Name nutritional mode
Name energy source
Name carbon source
List types of organisms
A

Chemoheterotroph
Organic compounds
Organic compounds
Many prokaryotes and Protista (fungi, animals and some plants)

24
Q

What are microbial mats?

A

Surface layers have access to O2 and CO2 and light –use oxygenic photosynthesis and aerobic cellular respiration
Deeper layers do not have access to O2 – use anoxygenic photosynthesis and anaerobic respiration and fermentation

25
Q

Explain how anoxygenic photosynthesis works

A

Anoxygenic photosynthesis = CO2 reduced to organic carbon
Absorbs sunlight using a different pigment – bacteriochlorophyll
Uses a single photo system and electron transport chain to produce ATP only
Electron donors are H2S, H2, ferrous iron (Fe2+) and arsenide (AsO3 3-)

26
Q

Define anaerobic respiration and fermentation

A 
Without O2, organic molecules are still oxidized to CO2
Oxidants used as electron acceptors instead of oxygen
-ferric acid (Fe 3+)
-hydrogen sullied (H2S)
-sulfur (SO4 2-)
-nitrogen (NO3 -)
-manganese (Mn 4+)
-arsenic (AsO4 3-)
27
Q

Role of bacteria in sulfur cycle

A

SO4 taken up by plants
Reduced to forms (-SH molecules) that can be used to make amino acids (ex. Cysteine)
Animals get S from food
H2S is rapidly oxidized to sulfur in presence of O2
Toxic to eukaryotic organisms

28
Q

Role of bacteria in nitrogen cycle

A

Nitrogen gas (N2) –> ammonia (NH3) –> Anammox
Anamoxx in Archaea: NH4+ + NO2- –> N2 + 2H2O
Ammonia –> nitrification (nitrite NO2-) –>nitrate (NO3-) –> denitrification

29
Q

How are prokaryotes classified?

A

6 important groups

  • proteobacteria
  • Green bacteria
  • cyanobacteria
  • gram-positive bacteria
  • spirochete
  • chlsmydias
30
Q

Prokaryotes is the what?

And bacteria is the what?

A

Prokaryotes is the domain
Bacteria is the classification
Have numerous evolutionary branches
Makes it difficult to define “species” when considering prokaryotes

31
Q

What are the 2 subgroups of proteobacteria?

A

Gram-negative bacteria

Free-living gram-negative proteobacteria

32
Q

Define gram-negative bacteria

A
  • purple sulfur bacteria
  • colour due to unique chlorophyll
  • photoautotrophic or photoheterotrophic
33
Q

Define free-living gram-negative proteobacteria

A
  • chemoheterotroph
  • intestinal bacteria (E.coli)
  • some cause human disease
34
Q

Name and define the subgroup of green bacteria

A

Gram-negative photosynthetic bacteria

  • found in hot springs (photoautotrophic)
  • marine and high salt environments (photoheterotrophic)
  • distinctive chlorophyll compared to plants
  • do not release oxygen as by-product of photosynthesis
35
Q

Give the other name for and define cyanobacteria

A

Cyanobacteria=blue-green algae

  • gram-negative aerobic photosynthetic prokaryotes
  • responsible for oxygen-based life on earth (algae/plants)
  • most morphologically diverse group of bacteria
  • some species form colonies
  • some species have specialized cell types
36
Q

Define gram-positive bacteria

A
  • primarily chemoheterotroph
  • many pathogenic species (Bacillus anthracis, staphylococcus, streptococcus)
  • some beneficial species (Lactobacillus–lactic acid fermentation–>pickles, yogurt)
37
Q

Define spirochete

A
  • gram-negative bacteria
  • propelled by rotation of helically spiralled flagella
  • enables movement in mud/sewage
  • beneficial/harmless species
  • found in human mouth
  • in termite intestine that digest cellulose
  • pathogenic species (syphilis)
38
Q

Define Chlamydias

A
  • gram-negative bacteria
  • cell walls with membrane outside
  • lack peptidoglycans
  • intercellular parasites that cause disease in animals
39
Q

What bacteria is tolerant to radiation and can break down radioactive waste?

A

Deinococcus radiodurans

40
Q

What bacteria is tolerant to a high temperature, is used in PCR techniques to create copies of DNA, because DNA polymerase is so heat-stable?

A

Thermos aquaticus

41
Q

Prokaryotes is the what?

Archaea is the what?

A

Prokaryotes is the domain

Archaea is the classification

42
Q

What are some of the unique characteristics of archaea?

A
  • some features like bacteria (prokaryotes, chromosomes, ribosomes
  • some features like eukaryotes (histones, enzymes)
  • some unique features (membranes, protein synthesis)
43
Q 
Bacteria:
Nucleus and membrane bound organelles?
DNA in circular form?
Ribosome size?
Photosynthesis with chlorophyll?
Capable of nitrogen fixation?
Capable of chemoautotrophy?
Membrane lipids ester-linked?
A 
NO
YES
70s
YES
YES
YES
YES
44
Q 
Archaea:
Nucleus and membrane bound organelles?
DNA in circular form?
Ribosome size?
Photosynthesis with chlorophyll?
Capable of nitrogen fixation?
Membrane lipids ester-linked?
Capable of chemoautotrophy?
A 
NO
YES
70S
NO
YES
NO
YES
45
Q

Name and define the first group of euryarchaeota

A

Methanogens:

  • methane generators
  • low-oxygen environments
  • obligate anaerobes in…anoxic sediments, large intestines of dogs/humans, hindguts of insects, rumen of livestock
46
Q

Name and define the second group of euryarchaeotes

A

Halophiles:

  • Highly saline environments
  • aerobic chemoheterotroph
  • obtain energy from sugars, alcohol, amino acids
  • some use light as secondary energy source
47
Q

Name and define the third group of euryarchaeotes

A

Extreme Thermophiles:

  • heat loving
  • hydrothermal vents, hotsprings
  • tolerate temperatures of 70-95 degrees Celsius
48
Q

Name and define the first group of crenarchaeota

A

Extreme thermophiles:

Higher optimal temperature range than euryarchaeota

49
Q

Name and define the second group of crenarchaeota

A

Psychrophiles:

  • cold loving
  • temperatures between -10 to -20 degrees Celsius
  • found in arctic and Antarctic oceans
50
Q

Name and define the third group of crenarchaeota

A

Mesophiles:

-many plankton in cool marine waters

51
Q

Define Korarchaeota

A
  • recognized by samples of DNA sequences
  • found in hydrothermal environments (never cultivated in lab)
  • nothing is known about their physiology
52
Q

Define Thaumarchaeota

A
  • may be most abundant cells in ocean

- chemoautotrophs that use ammonia (Anammox reaction in nitrogen cycle)

53
Q

Evolution of bacteria and archaea is a?

A

Intertwined network

54
Q

What do prokaryote studies help us to understand?

A
  • human mircobiome
  • ecosystem process
  • biotechnology
  • bioprocessing
  • biomimicry

Biology 1020 (9 decks)

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