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MicroBiology > CH 3d inner structures > Flashcards

CH 3d inner structures Flashcards

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1
Q

CH 3d

Cytoplasm

A 
Bounded by the plasma membrane
Highly organized (even without organelles) - cytoskeleton and many functional membrane extensions
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2
Q

CH 3d

Cytoskeleton

A

Structural elements of the cell:

  • microfilaments, actin
  • intermediate filaments
  • microtubules, tubulin Maintaining cell shape
    Cell division
    Organization/ protein localization within the cell
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3
Q

CH 3d

FtsZ

A

Part of cytoskeleton that forms a ring where the cell will divide and eventually constricts and pinches the bacteria into two new cells.

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4
Q

CH 3d

Internal membranes

A

Most, but not all bacteria, have extensive functional inner membranes that are associated with the plasma membrane (not separate organelles) - may be involved in respiration, photosynthesis, etc.

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5
Q

CH 3d

Inclusion Bodies

A 
Storage:
- nutrients
- waste
Reduce osmotic pressure
- make proteins insoluble (not drawing water into the cell)
Metabolic functions
Motility
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6
Q

CH 3d

Structure of Inclusion Bodies

A

Some are free, others bound by a protein shell or lipid layer.
Surrounded by extension of plasma membrane.

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7
Q

CH 3d

Inclusion Bodies and storage

A

Carbon (PBH)
Nitrogen (cyanophycin granules in cyanobacteria)
Phosphate (Corynebacterium diphtheriae - club shape comes from inclusion bodies)
Sulfur (waste - prevents sulfur from becoming toxic in the cell - gives Thiomargarita its sheen)

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8
Q

CH 3d

Inclusion Bodies and metabolic functions

A

Special type: carboxysome - location of the Calvin cycle, building sugar molecules (RuBisCo)

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9
Q

CH 3d

Inclusion Bodies and motility

A

Different kinds; two examples are gas vacuoles and magnetosomes

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10
Q

CH 3d

Gas vacuoles (inclusion bodies and motility)

A

Regulate gas in the gas vesicles, changing the buoyancy of the bacteria, allowing them to change level in water (closer to surface or bottom)

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11
Q

CH 3d

Magnetosomes (inclusion bodies and motility)

A

Small bodies composed of magnitite particles - can orient themselves up/down or N/S/E/W.
Often have 15 or so magnitite particles in a row to make up the magnetosome.

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12
Q

CH 3d

Ribosomes

A

Function: protein synthesis

  • very similar to eukaryotic ribosomes - many believe that ribosomes were originally a unique organism that came to live in coexistence with prokaryotic cells and then stayed in the cells as eukaryotes evolved. Structure: slightly smaller than eukaryotes; about 70S with the two units combined
  • large subunit (50S)
  • small subunit (30S)
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13
Q

CH 3d

Nucleiod

A

Generally a large, single, circular DNA molecule, not separated from the cytoplasm by a membrane.
Very organized - Nuclear Associated Proteins (supercoiling)
Example: E. coli = 4Mb = 1.4 mm

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14
Q

CH 3d

Plasmids

A

Extrachromosomal DNA - not required for bacteria to grow and reproduce normally, but it has genes that are advantageous under certain environmental conditions. When resources are scare, the plasmid won’t continue to replicate. small, double-stranded DNA that can exist independently of chromosome
Replicate autonomously.
Episomes:

  • plasmids that insert into the chromosome
  • replicate with the chromosome
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15
Q

CH 3d

Episomes

A

Plasmids that insert into the chromosome.

Replicate with the chromosome.

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16
Q

CH 3d

Common types of plasmids

A

Conjugation
- F plasmid (sex pilus)
- R plasmid (antibiotic resistance)
Bacteriocin-encoding
- inhibit growth of other bacteria; prevents competition for resources
Virulence
- encode factors involved in pathogenecity (capsule/ toxic proteins)
Metabolic
- enable bacteria to use a variety of food sources

17
Q

CH 3d

Pili

A

Short, hair-like appendages from cell surface
Involved in conjugation - can transfer DNA across species

sex pili involved in conjugation

18
Q

CH 3d

Fimbriae

A

Short, hair-like appendages from cell surface

Involved in attachment and motility

19
Q

CH 3d

Flagellum

pl. flagella

A 
Described based on location.
Same structure in all bacteria:
Filament
Hook
Basal body
20
Q

CH 3d

Types of flagella

A

Monotrichous: 1 flagellum
Amphitrichous: multiple flagella on one end of bacteria
Lophotricous: multiple flagella that come from same point
Peritrichous: flagella all over the cell

21
Q

CH 3d

Flagellum structure

A

Filament
- end that extends past cell wall/ outer membrane
- simple protein flagellin subunits arrange themselves in hollow tube
Hook
- gives bent flagellum a propeller-like movement
- covered in the sheath
Basal Body
- fairly complex motor region; rod parts spin
- movement driven by H+ gradient

22
Q

CH 3d

Bacterial motility

A

Swimming with flagella
Corkscrew movements of spirochetes
Fimriae
Gliding

23
Q

CH 3d

Taxis

A 
Directed motility - "random motion with a purpose"
- moves towards or away from certain stimulants; receptors detect presence of attractants or repellants
Types:
chemotaxis = nutrients/ repellants 
thermotaxis = temp
phototaxis = light
aerotaxis = oxygen
osmotaxis = osmotic pressure
24
Q

CH 3d

Flagella movement with taxis

A
  • Run: counterclockwise rotation, one spot to another
  • Tumble: clockwise rotation, orient cell Without a signal, they move randomly.
    If a bacteria detects a foodsource, they’ll run in that direction for a while before having to stop and tumble. Then they’ll start running again; if it’s in the direction of food, they’ll go a while before tumbling. If it’s not, then they’ll stop running, tumble, and hope that next time they run they’re going toward food.
25
Q

CH 3d

Swarming

A

Groups of cells moving together. Herd mentality of the colony working as a community.
Example: Myxococcus xanthus

26
Q

CH 3d

Axial Fibril

A

Internal flagellum in spirochetes - work in the periplasmic space between cell wall and outer membrane.
Causes corkscrew movement.

27
Q

CH 3d

Twitching and gliding

A

Involve fimbriae and/ or slime layer.
Twitching:

  • fimriae alternately extend and retract to move bacteria
  • intermittent, jerky Gliding:
  • may involved fimbriae, always has slime layer
  • smooth
28
Q

CH 3d

Endospores

A

Protective structure that is formed around DNA and most important proteins when conditions are bad - resistant to most things and allows bacteria to be dormant for extended periods of time.
Very thick structures - don’t take up stains/ impervious to chemicals
Generally G+ and soil species
- Clostridium
- Bacillus
- Sporosarcina

29
Q

CH 3d

Functions of endospores

A

Resistance to…

  • UV
  • desiccation
  • heat
  • chemical disinfectants
30
Q

CH 3d

Endospore structure

A 
Core (DNA and proteins)
Core wall
Cortex
Inner Coat
Outer Coat
31
Q

CH 3d

Endospore locations within the cell

A

Central
Subterminal
Terminal

32
Q

CH 3d

sporulation

A

making endospores, complex process in organized fashion over several hours

33
Q

CH 3d

Endospore return to vegetative state

A

(Becoming an actively growing cell again)
Complicated process needing exact environmental conditions

  • Activation
  • Germination
  • Outgrowth

MicroBiology (18 decks)

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