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MBIO 1010 > Cell surface structure, Endospores and Flagella > Flashcards

Cell surface structure, Endospores and Flagella Flashcards

Lectures 5-15

1
Q

What are capsules and slime layers composed of? What is their function?

A 
They're made of Polysaccharide / protein layers 
May be thick or thin, rigid or flexible 
Assist in attachment to surfaces 
Protect against phagocytosis 
Resist desiccation (loss of water)
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2
Q

What is a benefit to the sticky layer of capsules and slime layers?

A

Helps spread disease.

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3
Q

What structure is a filamentous protein structure which enables organisms to stick to surfaces or form pellicles (thin membrane)?

A

Fimbriae

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4
Q

What structure has a filamentous protein structure, is typically longer than fimbriae and assists in surface attachment?

A

Pili

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5
Q

What is the function of Pili?

A

Facilitate genetic exchange between cells (conjugation)

Type IV involves twitching motility

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6
Q

What are cell inclusion bodies?

A

Visible aggregates in cytoplasm
Carbon storage polymers
-Poly-β-hydroxybutyric acid (PHB): lipid
-Glycogen: glucose polymer

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7
Q

What are the type(s) of inclusion bodies?

A

Polyphosphates: accumulations of inorganic phosphate
Sulfur globules: composed of elemental sulpher
Magnetosomes: magnetic storage inclusions

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8
Q

What is the function of carbon storage polymers?

A

Poly-b-hydroxybutyrate (PHB)
-Lipid storage
Glycogen granules
-Polymer of glucose

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9
Q

What is the function of inorganic inclusions?

A

Polyphosphate granules – volutin
-Storage of phosphate and energy
Sulpher Globules
-Storage of sulfur used in energy generation

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10
Q

What are the intracellular granules of Magnetosomes composed of?

A

Fe3O4 or Fe3S4

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11
Q

What properties do Fe3O4 and Fe3S4 give Magnetosomes? Due to this where do the Magnetosomes migrate?

A

It gives them magnetic properties. This allows Magnetosomes to orient itself in a magnetic field
Bacteria migrate along Earth’s magnetic field- magnetotaxis

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12
Q

What are gas vesicles? Where are they found?

A

Spindle-shaped, gas-filled structures made of protein. They are found in planktonic cells.

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13
Q

What is the function of gas vesicles? What is special about them?

A

Their function is conifer buoyancy- this allows them to stay in a certain water body spot to maximize their sunlight absorption. The vesicles Function by decreasing cell density, and they are impermeable to water.

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14
Q

What are endospores? What are their characteristics?

A

Endospores are highly differentiated cells resistant to heat, harsh chemicals, and radiation.
They are the dormant stage of a bacterial life cycle, and it is ideal for them to be dispersed by animals, wind, water or animal gut.

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15
Q

True or False: endospores are found in all bacteria.

A

False: endospores are found in some gram positive bacteria.

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16
Q

True or False: something is sterile only if all endospores are destroyed.

A

True

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17
Q

Which gram+ bacteria produce endospores?

A

Bacillus sp. – aerobic Gram + rods

Clostridium sp. – anaerobic Gram + rods

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18
Q

What is the term used to describe a cell that is capable of normal growth and metabolically active?

A

Vegetative cell

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19
Q

Where is a endospore formed?

A

An endospore is metabolically inactive dormant cell that is formed inside the mother cell.

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20
Q

What triggers the formation of endospores? How long does it take for endospores to form?

A

Lack of nutrients triggers the formation of endospores. It takes 8-10 hours for them to form.

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21
Q

What are the protective layer(s) of the endospore? What are their characterisitcs?

A

Layers:
-Spore coat and cortex – protect against chemicals, enzymes, physical damage, and heat
-Two membranes – permeability barriers against chemicals
Core:
-Dehydrated – protects against heat
-Ca-dipicolinic acid and SASPs
-Protect against DNA damage

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22
Q

What can endospores resist?

A 
Boiling for hours (30) 
UV, gamma radiation 
Chemical disinfectants 
Dessication (lack of water)
Age
23
Q

How many stages are there in endospore formation? What are they?

A 
I- Asymmetric Cell Division
II- Septation
III- Mother cell Engulfs the Forespore 
IV- Formation of Cortex
V- Coat Synthesis
VI- Endospore matures
VII- Mother Cell is Lysed
24
Q

In which stage of endospore formation is the forespore surrounded by two membranes?

A

Stage III- Mother cell Engulfs the Forespore

25
Q

In which stage of endospore formation does a thick layers of peptidoglycan form between the two
membranes in a highly cross-linked layer- the core wall?
[At this point the loosely cross-linked layer – cortex (~ ½ of spore volume)]

A

Stage IV- Formation of Cortex

26
Q

In which stage of endospore formation does DNA replicates and identical chromosomes are pulled to opposite ends of the cell?

A

Stage I- Asymmetric Cell Division

27
Q

In which stage of endospore formation does a protein layers surround the core wall (the spore coat or Exosporium) that will protect the spore from chemicals and enzymes?

A

Stage V- Coat Synthesis

28
Q

In which stage of endospore formation does the mature spore get released and the mother cell disintegrates?

A

Stage VII- Mother Cell is Lysed

29
Q

In which stage of endospore formation does the cell divide into two unequal compartments the Forespore and the Mother Cell?

A

Stage II- Septation

30
Q

In which stage of endospore formation does the core is dehydrated (~ 10 – 30% of a vegetative cell’s water content)?

A

Stage VI- Endospore Matures

31
Q

After stage V- Coat Synthesis, what accumulates in the core to stabilize the DNA?

A

Calcium, dipicolinic acid and small acid soluble proteins (SASPs)

32
Q

What are flagella? What is their function?

A

Flagella are hollow protein filimants that impart motility. The filament aspect of it will NOT be solid- it is like a tube with only walls. The flagella is not continuous with the cytoplasm because of the way it is bolted into the membrane.

33
Q

Flagella has to be _______ for us to be able to view them.

A

Stained

34
Q

What are the 4 kinds of flagella? Where are they located on the microorganism?

A

Monotrichous – single flagellum
-Polar or subpolar
Amphitrichous – Flagella at opposite ends
Lophotrichous – Multiple flagella in a single tuft
Peritrichous – Flagella distributed around cell.

35
Q

What component in flagella structure is a rigid helical protein (~ 20 µm long) and is composed of identical protein subunits (flagellin)?

A

The filament

36
Q

In flagella structure what is the basal body (the motor)?

A

The basal body is what connects the flagella to the cell wall. It consists of central rod that passes through series of rings.

37
Q

What are the series of rings the basal body of a flagella passes through? Where is each ring located?

A 
L ring – LPS layer
-in gram- 
P ring – Peptidoglycan 
MS ring – Membrane 
C ring – Cytoplasm (associated with membrane)
38
Q

What component in flagella structure is the flexible coupling between filament and basal body, as well as made up of proteins?

A

The hook

39
Q

Where does the energy to use the flagella come from? How does it work?

A

The energy comes from the proton motive force (PMF).
The gradient of protons (H+) moves across the cytoplasmic membrane:
-High [H+] outside
-Low [H+] inside
Mot proteins form a channel that allows H+ to move into the cytoplasm which provides the energy to turn the flagellum.

40
Q

What occurs in flagellar synthesis?

A

First several genes are required for flagellar synthesis and motility. The MS ring is made first. Other proteins and hook are made next, and finally the Filament grows from tip.

41
Q

In flagella movement what what is the difference in swimming motions?

A

Peritrichously flagellated cells move slowly in a straight line, while polarly flagellated cells move more rapidly and typically spin around.

42
Q

When peritrichous flagella are moving in a straight line, in which direction are their flagella rotating? What about when they tumble?

A

Straight Line- counter-clockwise rotation

Tumble- clockwise rotation

43
Q

When polary flagella have a range of movements depending on if they have direction or not. In which direction are their flagella rotating when they have direction? What about when they are unidirectional?

A

Reversible Flagella
Polar Flagella moving forward- counter-clockwise rotation
Polar Flagella moving backward- clockwise rotation
Unidirectional Flagella
Polar Flagella moving forward- clockwise rotation
Polar Flagella changing direction- clockwise rotation

44
Q

What is gliding motility?

A

It is flagella-independent motility. It is slower and smoother than swimming, and requires surface contact.

45
Q

What are the mechanisms included in gliding motility?

A

Excretion of polysaccharide slime
Type IV pili
Gliding-specific proteins

46
Q

What is taxis regarding flagella?

A

Directed movement in response to chemical or physical gradients.

47
Q

What are the different type(s) of taxis?

A 
Chemotaxis: response to chemicals 
Phototaxis: response to light  
Aerotaxis: response to oxygen (aversion) 
Osmotaxis: response to ionic strength 
Hydrotaxis: response to water
48
Q

Where is chemotaxis best studied?

A

E. coli

49
Q

True or False: Bacteria respond to spatial, not temporal, difference in chemical concentration.

A

False: Bacteria respond to temporal, not spatial, difference in chemical concentration.

50
Q

What kind of behavior do chemotaxis responding bacteria exhibit? How do they sense the chemotaxis?

A

The bacteria exhibit “run and tumble” behavior.

Attractants and Repellents are sensed by chemoreceptors.

51
Q

What is biased random walk? Give an example.

A

Directed movement toward an attractant or away from a repellent.
Ex) E. coli shows biased random walk toward glucose when there is a concentration gradient.

52
Q

During biased random walk run and tumble behavior is still present. What happens when the bacteria sense an increase in [glucose]?

A

The tumble is delayed

The run lasts longer

53
Q

How do we measure chemotaxis?

A

We measured by inserting a capillary tube containing an attractant or a repellent in a medium of motile bacteria.

54
Q

How do you interpret the results when measuring chemotaxis?

A

When the capillary tube is filled with cells- attractant is present
When the capillary tube is empty of cells- repellent is present
When capillary tube has an average amount of cells- control

MBIO 1010 (14 decks)

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