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Microbiology Lecture > Topic 4 - Prokaryotic Cell Morphology Part 2 > Flashcards

Topic 4 - Prokaryotic Cell Morphology Part 2 Flashcards

0
Q

Functions of external structures in bacteria and archaea

A
  • Protection
  • Attachment to surfaces
  • Horizontal gene transfer
  • Cell movement
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1
Q

Some structures that extend beyond the cell envelope in bacteria and archaea

A
  • Fimbriae
  • Pili
  • Flagella
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2
Q

Short, thin, hairlike, proteinaceous appendages (up to 1,000/cell)

A

Fimbriae (s. fimbria)

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3
Q

What is the job of fimbriae?

A
  • Mediate attachment to surfaces

- Some (type IV fimbriae) required for motility or DNA uptake)

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4
Q
  • Longer, thicker, and less numerous then fimbriae
A

Sex pili (pl, pilus)

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5
Q

Functions of sex pili

A
  • Genes for formation found on plasmids

- Required for conjugation

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6
Q

Threadlike, locomotor appendages extending outward from plasma membrane and cell wall

A

Flagella

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7
Q

Functions of flagella

A
  • Motility and swarming behavior
  • Attachment to surfaces
  • May be virulence factors
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8
Q
  • Thin, rigid protein structures that cannot be observed with bright-field microscope unless specially stained
  • Pattern of flagellation varies
A

Domain Bacteria flagella

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9
Q

One flagellum

A

Monotrichous

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10
Q

Flagellum at end of cell

A

Polar flagellum

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11
Q

One flagellum at each end of cell

A

Amphitrichous

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12
Q

Cluster of flagella at one or both ends

A

Lopchotrichous

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13
Q

Flagella spread over entire surface of cell

A

Peritrichous

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14
Q

Three parts of a flagellum

A
  1. Filament
  2. Hook
  3. Basal body
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15
Q
  • Extends from surface to the tip of flagellum
  • Hollow, rigid cylinder
  • Composed of the protein flagellin
  • Some bacteria have a sheath around filament
A

Filament

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16
Q

The protein that composes the flagellum filament

A

Flagellin

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17
Q
  • In the flagellum

- Links filament to basal body; made of protein

A

Hook

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18
Q
  • Series of rings that drive flagellar motor
A

Basal body

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19
Q

Explain flagellar synthesis

A
  1. Complex process involving many genes and proteins
  2. New flagellin molecules transported through the hollow filament to tip
  3. Filament subunits self-assemble with help of filament cap at tip, not base
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20
Q

Motility in domain Bacteria and Archaea

A
  1. Flagellar movement
  2. Spirochete motility
  3. Twitching motility
  4. Gliding motility
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21
Q

Directed cell movement in response to some stimulus

A

Taxis

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22
Q

Move toward chemical attractants such as nutrients, away from harmful substances

A

Chemotaxis

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23
Q

Bacteria and Archaea can also move in response to what?

A

Temperature, light, oxygen, osmotic pressure, and gravity

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24
Q

Changing concentrations of chemical attractants and chemical repellents does what?

A

Binds chemoreceptors of chemosensing system

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25
Q
  • Flagellum rotates like a propeller

- Very rapid rotation up to 1100 revolutions/sec

A

Bacterial flagellar movement

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26
Q

The two parts of a flagellum

A
  1. Rotor

2. Stator

27
Q

How does the rotor in the flagellum work?

A

C (FliG protein) ring and MS ring turn and interact with stator

28
Q

Mechanic machine made of Mot A or Mot B proteins

A

Stator

29
Q

How do stators work?

A
  1. Form channel through plasma membrane
  2. Protons move through Mot A and Mot B channels using energy of proton motive force
  3. Torque powers rotation of the basal body and filament
30
Q

Have corkscrew shape which allows them to move in viscous media

A

Spriochete Motility

31
Q

How does spirochete motility work?

A
  1. Multiple flagella form axial fibril which winds around the cell
  2. Flagella remain in periplasmic space inside outer sheath
  3. Corkscrew shape exhibits flexing and spinning movements
32
Q
  • Involves contact with surface

- May involve Type IV pili and slime

A

Twitching and gliding motility

33
Q
  • Pili at ends of cell
  • Short, intermittent, jerky motions
  • Cells are in contact with each other and surface
A

Twitching

34
Q
  • Smooth movements
A

Gliding

35
Q

Prokaryotic cytoplasmic structures

A
  • Cytoskeleton
  • Intracytoplasmic membranes
  • Inclusions
  • Ribosomes
  • Nucleoid and plasmids
36
Q

Material bounded by the plasmid membrane

A

Cytoplasm

37
Q

What is the cytoplasm composed of?

A
  • 90-94% water
  • Dissolved solutes (ions, sugars, amino acids)
  • Somewhat viscous
  • Many enzymes and ribosomes
  • Cytoskeleton? Cyclosis?
38
Q

Network of fibrous proteins within cytoplasm

A

The cytoskeleton

39
Q

What is special about the cytoskelton in regards to the different domains?

A

Homologs of all 3 eukaryotic cytoskeletal elements have been identified in bacteria and 2 in archaea

40
Q

Function of cytoskeleton in things besides eukaryotes

A

Role in cell division, protein localization, and determination of cell shape

41
Q

Homologs of all 3 eukaryotic cytoskeletal elements have been identified in ____

A

Bacteria

42
Q

Membrane bound storage structures containing granules of organic or inorganic material that are stockpiled by the cell for future use

A

Inclusions

43
Q

Some inclusions are enclosed by a ________, but not a _____

A
  • single layer membrane

- Unit membrane

44
Q

Three facts about inclusions

A
  1. Membranes vary in composition
  2. Some made of proteins; others contain lipids
  3. May be referred to as microcompartments
45
Q

Storage of nutrients, metabolic end products, energy, building blocks

A

Storage Inclusions

46
Q

Not bound by membranes but compartmentalized for a specific function

A

Microcompartments

47
Q

Contain the enzyme ribulose - 1,5,- bisphosphate carboxylase, enzyme used for CO2 fixation

A

Carboxysomes - CO2 fixing bacteria

48
Q
  • Found in aquatic, photosynthetic bacteria and archaea

- Provide buoyancy in gas vesicles

A

Gas vacuoles

49
Q
  • Found in aquatic bacteria

- Magnetite particles for orientation in Earth’s magnetic field

A

Magnetosomes

50
Q

What is in the cytoskeleton of magnetosomes and what does it do?

A

Protein MamK

- Helps form magnetosome chain

51
Q

Why are ribsomomes complex structures?

A
  • Consist of protein and rRna

- Site of protein synthesis

52
Q

Complex, dormant structure formed by some bacteria in various locations within the cell

A

The bacterial endospore

53
Q

What is the function of the bacterial endospore

A

To survive extreme environments for the organism

54
Q

What environmental conditions are the bacterial endospore resistant to?

A
  • Heat
  • Radiation
  • Chemicals
  • Dessication
55
Q

What does the endospore structure contain?

A
  1. Spore surrounding by thin covering called exosporium
  2. Thick layers of protein form the spore coat
  3. Cortex, beneath the coat, thick peptidoglycan
  4. Core has nucleoid and ribosomes
56
Q

What makes an endospore so resistant?

A
  • Calcium (complexed with dipicolinic acid)
  • Small, acid-soluble, DNA-binding proteins (SAPSs)
  • Dehydrated core
  • Spore coat and exsporium protect
57
Q
  • Process of endospore formation

- Occurs in a few hours (up to 10)

A

Sporulation

58
Q

When does sporulation commence?

A

Normally commences when growth ceases because of lack of nutrients, or presence of toxic substances

59
Q

Transformation of endospore into vegetative cell complex, multistage process

A

Germination

60
Q

Three steps to formation of vegetative cell

A
  1. Activation
  2. Germination
  3. Outgrowth
61
Q
  • Prepares spores for germination

- Often results from treatments like heating

A

Activation

62
Q
  • Environmental nutrients are detected
  • Spore swelling and rupture of absorption of spore coat
  • Loss of resistance
  • Increased metabolic activity
A

Germination

63
Q

Emergence of vegetative cell

A

Outgrowth

64
Q
  • May exist in many copies in cell
  • Inherited stably during cell division
  • Curing is the loss of a plasmid
A

Plasmids

65
Q

What is classification of plasmids based on?

A

Mode of existence, spread, and function

Microbiology Lecture (5 decks)

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