Chapter 22 Flashcards

1
Q

Relationships between microbes

A

Symbiosis—rela:onships between microbes
•  Parasite—microorganism benefits at the expense of the host
•  Pathogenic—microorganism causes disease in the host
•  Commensal—microorganism does not affect host
•  Mutualis:c—the microbe benefits the host

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2
Q

Symbioses between microbes: Liche

A

Fungus and alga or cyanobacteria living in symbiosis with one another
•  Phototroph produces organic material for fungus
•  Fungus

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3
Q

Fungus and alga or cyanobacteria living in symbiosis with one another
•  Phototroph produces organic material for fungus
•  Fungus

A

  Anchors phototroph–  Produces lichen acids to

dissolve inorganic nutrients –  Water uptake

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4
Q

Consortia

A

Microbial mutualisms

•  Example: 13-‐‐69 Non-‐‐mo:le phototrophic green sulfur bacteria (epibionts) and one mo:le non-‐‐phototrophic bacteria

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5
Q

Consortia

A

Epibiont in genus Chlorobium
•  Scotophobotaxis•  Chemotaxis towards sulfide •  Fusion of periplasms•  Epibiont supplies α-‐‐ketoglutarate to central
microbe

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6
Q

Legume-‐‐root nodule symbiosi

A
  •   Legumes—clover, alfalfa, beans, peas, soybeans
  •   Rhizobia—nitrogen-‐‐fixing symbionts of plants
  •   Root nodules—rhizobial infec:on of legume roots
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7
Q

Root nodules

A

  Leghemoglobin—binds oxygen to protect nitrogenases, produced by rhizobia
•  10,000:1—bound oxygen:free oxygen in nodules

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8
Q

Bacteroid

A

differen:ated rhizobial cell

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9
Q

Stem nodules on Sesbania are formed

by Azorhizobium

A

Tropical aqua:c legumes

•  Some contain Bradyrhizobium -‐‐ photosynthe:c

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10
Q

Non-‐‐legume nitrogen-‐‐fixing symbiosis

A

Azolla-‐‐Anabaena
– Rice paddies
– Red arrow -‐‐ heterocyst

•  Alnus-‐‐Frankia
– Vesicles for N2 fixa:on

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11
Q

Agrobacterium and crown gall disease

A

Uncontrolled growth of :ssue
•  A. tumefaciens
•  Ti (tumor inducing) plasmid must be presen

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12
Q

Agrobacterium T-‐‐DNA is transferred to the plant

A

Genes for tumor forma:on and opines
•  Opines—modified amino acids that serve as source of carbon and nitrogen for bacteria
– Octopine– Nopaline

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13
Q

Symbioses between microbes: Mycorrhizae

A

•  “fungus root” •  Partners coevolved •  Photosynthe:c partner
provides carbon compounds
•  Fungal partner allows for
absorp:on and nutrient availability

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14
Q

Symbioses between microbes: Endomycorrhizae

A

•  Fungal mycelium embeds in root :ssue •  Most common—arbuscular mycorrhizae -‐‐
Glomeromycota
•  Hyphopodium (HP)—aeachment structure •  Spore (SP)

I

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