Prokaryotic Cells Flashcards

1
Q

Name three intracellular membranes in photosynthetic bacteria that can be considered organelles.

A
  • Intracytoplasmic membrane (proteobacteria)
  • Thylakoid membrane compartments (cyanobacteria)
  • Chlorosome compartments (Chlorobiaceae)
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2
Q

What do the three intracellular membranes in photosynthetic bacteria have in common?

A

They all maximise the efficiency of photosynthesis by

1) increasing the number photosynthetic protein complexes
2) maximizing the size of the light-exposed membrane surface
3) providing an idealized subcellular environment for photosynthesis

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3
Q

What are Planctomycetes?

A

True bacteria that contain a nuclear envelope

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4
Q

What percentage sequence identity can be found between MreB and eukaryotic actin?

A

15% sequence identity

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5
Q

What percentage sequence identity can be found between ParM and eukaryotic actin?

A

12% sequence identity

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6
Q

What is the role of

a) MreB?
b) ParM?
c) MamK?

A

a) MreB = cell shape
b) ParM = DNA partitioning
c) MamK = organelle assembly

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7
Q

Explain how ParM filaments are dynamic.

A
  • Polymerisation of ATP-bound ParM occurs at both ends.
  • ATP-hydrolysis occurs spontaneously.
  • ParM is unstable when ParM-ADP is at an end.
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8
Q

Explain how ParM filaments segregate plasmids.

A
  1. ParR binds the centromeric DNA-sequence
  2. ParM polymerizes and binds to ParR
  3. Filament elongation separates the plasmids
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9
Q

What is the sequence identity between FtsZ and tubulin?

A

10-18%

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10
Q

What does FtsZ do?

A

Forms a ring at the cell cleavage site

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11
Q

If a cell has a mutant FtsZ, what is it defective in?

A

Cell separation

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12
Q

Give the four modes of motility.

A
  1. Swimming
  2. Swarming
  3. Gliding
  4. Twitching
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13
Q

When does swarming occur?

A

On surfaces

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14
Q

What is the swimming rate in bacteria?

A

25–160 micrometer per second

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15
Q

How many rotations per second in a flagellum?

A

100-300

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16
Q

What is the rate of surface-attached motility?

A

2-5 micrometers per second

17
Q

How many pilli per cell?

A

100-1000

18
Q

How long is a pillus on average?

And how wide?

A

1-2 micrometres long, 2-8 nanometers wide

19
Q

How do Type 3 and Type 6 secretion systems work?

A

Inject proteins (15-30 proteins)

20
Q

What do swimming or swarming depend on?

A

A rotating flagellum (that does not contain microtubules)

21
Q

What is twitching motility based on?

A

Type 4 Pilli

22
Q

What are type 4 pilli?

A

Protein assemblies that extend and retract to pull the cellover surfaces

23
Q

How are cytosolic bacteria able to escape the phagocytic vesicle?

A
  • By polymerising host actin at one end of the cell

- This “pushes” the bacterium through the cell but also spreads the bacterium from one host cell to the next