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Biology 1020 > Bacteria and Archaea > Flashcards

Bacteria and Archaea Flashcards

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
Explain how anoxygenic photosynthesis works
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
Define anaerobic respiration and fermentation
``` 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
Role of bacteria in sulfur cycle
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
Role of bacteria in nitrogen cycle
Nitrogen gas (N2) --> ammonia (NH3) --> Anammox Anamoxx in Archaea: NH4+ + NO2- --> N2 + 2H2O Ammonia --> nitrification (nitrite NO2-) -->nitrate (NO3-) --> denitrification
29
How are prokaryotes classified?
6 important groups - proteobacteria - Green bacteria - cyanobacteria - gram-positive bacteria - spirochete - chlsmydias
30
Prokaryotes is the what? | And bacteria is the what?
Prokaryotes is the domain Bacteria is the classification Have numerous evolutionary branches Makes it difficult to define "species" when considering prokaryotes
31
What are the 2 subgroups of proteobacteria?
Gram-negative bacteria | Free-living gram-negative proteobacteria
32
Define gram-negative bacteria
- purple sulfur bacteria - colour due to unique chlorophyll - photoautotrophic or photoheterotrophic
33
Define free-living gram-negative proteobacteria
- chemoheterotroph - intestinal bacteria (E.coli) - some cause human disease
34
Name and define the subgroup of green bacteria
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
Give the other name for and define cyanobacteria
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
Define gram-positive bacteria
- primarily chemoheterotroph - many pathogenic species (Bacillus anthracis, staphylococcus, streptococcus) - some beneficial species (Lactobacillus--lactic acid fermentation-->pickles, yogurt)
37
Define spirochete
- 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
Define Chlamydias
- gram-negative bacteria - cell walls with membrane outside - lack peptidoglycans - intercellular parasites that cause disease in animals
39
What bacteria is tolerant to radiation and can break down radioactive waste?
Deinococcus radiodurans
40
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?
Thermos aquaticus
41
Prokaryotes is the what? | Archaea is the what?
Prokaryotes is the domain | Archaea is the classification
42
What are some of the unique characteristics of archaea?
- some features like bacteria (prokaryotes, chromosomes, ribosomes - some features like eukaryotes (histones, enzymes) - some unique features (membranes, protein synthesis)
43
``` 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? ```
``` NO YES 70s YES YES YES YES ```
44
``` 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? ```
``` NO YES 70S NO YES NO YES ```
45
Name and define the first group of euryarchaeota
Methanogens: - methane generators - low-oxygen environments - obligate anaerobes in...anoxic sediments, large intestines of dogs/humans, hindguts of insects, rumen of livestock
46
Name and define the second group of euryarchaeotes
Halophiles: - Highly saline environments - aerobic chemoheterotroph - obtain energy from sugars, alcohol, amino acids - some use light as secondary energy source
47
Name and define the third group of euryarchaeotes
Extreme Thermophiles: - heat loving - hydrothermal vents, hotsprings - tolerate temperatures of 70-95 degrees Celsius
48
Name and define the first group of crenarchaeota
Extreme thermophiles: | Higher optimal temperature range than euryarchaeota
49
Name and define the second group of crenarchaeota
Psychrophiles: - cold loving - temperatures between -10 to -20 degrees Celsius - found in arctic and Antarctic oceans
50
Name and define the third group of crenarchaeota
Mesophiles: | -many plankton in cool marine waters
51
Define Korarchaeota
- recognized by samples of DNA sequences - found in hydrothermal environments (never cultivated in lab) - nothing is known about their physiology
52
Define Thaumarchaeota
- may be most abundant cells in ocean | - chemoautotrophs that use ammonia (Anammox reaction in nitrogen cycle)
53
Evolution of bacteria and archaea is a?
Intertwined network
54
What do prokaryote studies help us to understand?
- human mircobiome - ecosystem process - biotechnology - bioprocessing - biomimicry

Biology 1020 (9 decks)

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