Bacterial Capsules, Inclusions, and Endospores Flashcards

1
Q

What is a bacterial capsule?

A
  • usually composed of polysaccharides
  • well organized and not easily removed
  • seen well on a negative stain
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2
Q

What are the advantages of having a bacterial capsule?

A
  • allow for attachment to surfaces and each other (biofilms)
  • helpful for nutrient absorption
  • protects against desiccation, phagocytosis, viruses, detergents, toxins, and antimicrobials
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3
Q

What are slime layers?

A
  • similar to capsules except diffuse, unorganized and easily removed
  • may aid in motility
  • not seen well on a negative stain
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4
Q

What are cell inclusions?

A
  • aggregates of organic or inorganic material
  • can be granules, crystals, or globules
  • some enclosed by a single-layered “membrane” or invaginations of the plasma membrane
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5
Q

What are storage inclusions?

A
  • store nutrients, metabolic end products, and energy building blocks
  • ex: carbon (glycogen, PHB), phosphate granules, sulfur globules, and nitrogen (cyanophycin granules)
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6
Q

What are carbonate minerals?

A
  • stored minerals used for stabilization in water

- ex: found in aquatic bacteria in alkaline lakes

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7
Q

What are gas vesicles?

A
  • store gas
  • found in cyanobacteria (use oxygenic photosynthesis)
  • have hollow protein tubes only permeable to gases
  • aid in motility
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8
Q

What are magnetosomes?

A
  • magnetic bacteria
  • held in invaginations of the cytoplasmic membrane
  • typically found in water at the bottom (low O2 conditions)
  • attracted to Earth’s magnetic field
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9
Q

What are bacterial endospores?

A
  • complex, dormant, survival structures formed by some bacteria
  • have various locations in the cell (species specific)
  • resistant to heat/freezing, radiation, chemicals, starvation, and desication
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10
Q

What are the different locations of the endospore?

A
  • central
  • subterminal (close to end)
  • terminal
  • swollen sporangium (in a mother cell)
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11
Q

What is the structure of an endospore?

A
  • exporium on the outside
  • spore coat
  • outer membrane
  • cortex
  • germ cell wall
  • inner membrane
  • core
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12
Q

What is the exosporium?

A

a thin outside layer of the endospore made of protein

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13
Q

What is the spore coat made of?

A

proteins, very protective

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14
Q

What is the cortex made of?

A

peptidoglycan, but less cross linked

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15
Q

What layers of the endospore make up the vegetative cell?

A

germ cell wall, inner membrane, and core

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16
Q

What is the core of an endospore made of?

A
  • cytoplasm of the cell
  • ribosomes, DNA, enzymes
  • very dehydrated (frozen state)
17
Q

What makes an endospore so resistant?

A
  • the core has low water content
  • calcium dipicolinate binds water to dehydrate the core
  • small, acid-soluble, DNA-binding proteins (SASPs) compact the DNA to keep it safe from the environment
  • core has a slightly lower pH to keep enzymes from functioning
  • exosporium and spore coat provide protection
18
Q

What triggers endospore development?

A
  • harsh conditions

- typically a lack of nutrients that keeps the bacteria from being able to divide normally

19
Q

What is the process of sporulation and germination?

A
  1. Asymmetric cell division commits the cell to sporulation. (Stage I)
  2. The cell is divided into prespore and mother cell by a septum. (Stage II)
  3. The prespore gets an outer membrane and becomes engulfed by the cell. (Stage III)
  4. The cortex is formed around the endospore. (Stage IV).
  5. The spore coat is added. Ca2+ and dipicolinic acid uptake occurs. SASPs are formed. (Stage V).
  6. The cell matures and eventually lyses (Stage VI, VII).
  7. The now free endospore germinates into a vegetative cell which can divide by binary fission or begin the process of sporulation again.
20
Q

How is the vegetative cell formed?

A
  • activation prepares spores for germination (ex: heating)
  • during germination, environmental nutrients are detected
  • spore swelling and rupture of the spore coat occurs causing the cell to take in water
  • endospores are no longer resistant and metabolic activity is increased
  • eventually outgrowth occurs, where the vegetative cell emerges
  • the exosporium, spore coat, outer membrane, and cortex are left behind