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Microbiology > Test 1 - Escheria coli > Flashcards

Test 1 - Escheria coli Flashcards

1
Q

What is its genus? What does it mean for its structure and cell wall?

A

Escheria; Rod-shaped and Gram -

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2
Q

What is its organization in terms of flagella?

A

Peritrichous.

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3
Q

What is its class and group? What does its group mean?

A

Class: Gamma Proteobacteria
Group: Enterobacteria, or bacteria living in gut.

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4
Q

What are 4 other enterobacteria and their pathogenic tendencies?

A
  1. sarmolnella - typhod
  2. shigella - dystntry
  3. klebsiella - pneumonia
  4. yersenia : bubonic plague
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5
Q

Is it an aerobe or an anaerobe? What metabolism does it perform?

A

Facultative Anaerobe. Glycolysis, fermentation, and oxidative phosphorylation.

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6
Q

Explain the flow of phosphate in glycolysis. Remember to include NADH and ATP in explanation.

A
  1. Glucose (6 C) –> 1,6 Biphosphate (6 C, 2 P) with 2 ATP usage; Phosphate comes from ATP
  2. 1,6 Biphosphate (6 C, 2 P) –> 2 glyceraldehyde- 3 Phosphate (6 C, 2 P); Split
  3. 2 Glyceraldehyde-3 Phosphate (3 C, 2 P) –> 2 1,3-biphosphate (3 C, 4 P); 2 Phosphate comes from cytosol (!!!!) while 2 P is also used in NAD+ to form NADH. This step is missing enzymes, so it seems counterintuitive.
  4. 2 1,3-biphosphate (3 C, 4 P) –> 2 Pyruvate (3 C) as 4 ADP molecules steal the 4 P from biphosphate to create 4 ATP.
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7
Q

What is the gross output of glycolysis? The net?

A

Gross: 4 ATP and 2 NADH
Net: 2 ATP and 2 NADH

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8
Q

In glycolysis, _____ _____ is used to power ATP production

A

inorganic phosphate

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9
Q

What is the NAD+ is for? What is glycolysis also called because of that?

A

4 phosphate group transfer. Substrate Level Phosphorylation.

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10
Q

In glycolysis, what needs to be replenished? What process does this?

A

NAD+; Fermentation

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11
Q

There are 3 types of fermentation. E. coli performs…

A

Mixed Acid Fermentation (all 3 types).

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12
Q

In which fermentations do NAD+ get replenished? In which does it not? Why do organisms bother performing the last process?

A

NAD+ gets replenished when pyruvate –> lactic acid or Ethanol with CO2.
NAD+ does not get replenished formic acid, CO2, and H2O are produced. This is used only when the buildup of lactic acid, ethanol and/or pyruvate gets dangerous.

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13
Q

In aerobic conditions, E. coli can perform 2 metabolic processes known as…

A

TCA Cycle and Oxidative Phosphorylation.

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14
Q

In terms of using pyruvate (but NOT in terms of NAD+ replenishment), fermentation is similar to an aerobic process named…

A

TCA Cycle

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15
Q

In TCA Cycle, what is used, and what is produced? What is the net gain?

A

Pyruvate is used to produce 3 CO2, 4 NADH, FADH2, and GTP (eventually ATP). Net gain of 1 ATP.

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16
Q

What process uses TCA Cycle’s products, 4 NADH and FADH2?

A

Oxidative Phosphorylation.

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17
Q

In Oxidative Phosphorylation, the results of FCA Cycle are used for what purpose? What also is used for the same purpose? What drives the final step in ox-pho?

A

All gets deprotonated to create a [H+] outside the cell. O2 + 4H+ is also used to create 2 H2O and H+ (outside the cell). The final step uses F1/F0 ATPase.

18
Q

What is the purpose of F1? F0?

A

F1: proton channel
F0: Makes ATP

19
Q

Does E. coli grow? How?

A

Yes, by elongation

20
Q

Does E. coli develop? How?

A

No.

21
Q

How does E. coli reproduce? Explain how the genome gets copied. Explain how the elongated cell becomes 2 cells.

A

By binary fission. Haploid and circular chromosome gets copied from origin of replication (ori). The “replication bubble” unwinds outwards to crate a Theta structure (looks similar to Greek letter theta), until there are 2 separate circular haploid genomes. PM and CW (Septum) is formed in the middle until it forms 2 separate organisms.

22
Q

What is Conjugation? What is it not?

A

Conjugation is transfer of genetic info from one cell to another. It is not replication and not about the cell’s own genetic information.

23
Q

In conjugation, what is the genetic information called? What does it code for? What does it allow the cell to do?

A

Episome. Codes for Sex Pillus, thereby making the cell F+ cell, allowing it to propagate the episome more to other F- cells.

24
Q

How many chemoreceptors do E.coli have? Name one and its attractants.

A
  1. Tar Receptor, attracted to aspartine, maltose, Co, and Ni.
25
Q

What are the two mechanisms of chemotaxis? What directions?

A
  1. Tumble (Random) – CW

2. Run (Directional) – CCW

26
Q

With taxis, ++ length of run as long as it leads to…

A

+ [chemical]

27
Q

Is the receptor-molecule bond short-lived or long-lived? Why?

A

Short-lived, because food source presumably moves all the time as well.

28
Q

Chemotaxis: Why is E. coli thought to have a short term memory?

A

Cell must constantly be looking for a + [ligand] to get closer to the food than it already is.

29
Q

Chemotaxis: What is MCP? What does it stand for?

A

Methyl-accepting Chemotaxis Protein. Binds to ligand.

30
Q

Chemotaxis: What is CheW? What is CheA? What are their functions?

A

CheW aids MCP-CheA binding

CheA is what drives the flagella motion.

31
Q

Chemotaxis: CheA is activated by … Activation means this chemical process.

A

Absence of Ligand. Phosphorylated. (Auto-phosphorylation)

32
Q

Chemotaxis: CheA’s phosphate is important because it…

A

is transfered to other proteins (CheY and CheB)

33
Q

Chemotaxis: Relate CheY, CheA, CheZ, and Phosphorylated forms of the three proteins.

A
  1. CheZ is constantly dephosphorylated, so it acts as a ruler for [CheA-P].
  2. CheA-P phosphorylates CheY constantly.
  3. CheA-P only when the ligand is missing. Hence, CheA-P > CheZ –> CheY-P –> CW tumble.
  4. If ligand exists, CheA is dephosphorylated (and hence CheY is also dephosphorylated), and CheA-P < CheZ –> CheY –> CCW run.
34
Q

Chemotaxis: What Che protein controls flagella movement? What are Che accessory proteins?

A

CheY. CheA & CheZ.

35
Q

Chemotaxis: What Che protein and another protein controls short-term memory?

A

MCP and CheR (Remember)

36
Q

Chemotaxis: What causes MCP to recognize higher [ligand]? What happens with [ligand] stays constant? With CheY? With CheB?

A
  • MCP is Methylated by CheR. Its affinity for ligand decreases, and MCP lets go of ligand.
  • That means that cheA may autophosphorylate again, and hence causes CheA-P > CheZ, hence causes CheY to be phosphorylated, and hence CheY-P causes tumble.
  • Meanwhile, the fact that CheA-P > CheZ means that CheA-P can phosphorylate CheB. CheB-P is a de-methylizing agent, and hence causes de-methylation of MCP. If E.coli, during the tumble, have encountered a + [ligand], MCP will NOT let go of its ligand despite continued CheR activity. [is CheR active all the time?]
37
Q

Chemotaxis: What happens, after the tumble above, when there is ++ [ligand]?

A

MCP is, despite being methylated by CheR, still bound to ligand due to +[ligand]. This means that CheA is not phosphorylated. This means that CheA-P < CheZ, which means that CheY is also dephosphorylated. This means the organism will run CCW.

38
Q

Chemotaxis: What is used for measure-stick of CheA-P in Short Term Memory?

A

CheZ

39
Q

Chemotaxis: T/F: Affinity (whether MCP is Methylated) does not determine run/tumble.

A

True. It just relays information about [].

40
Q

Chemotaxis: How is CheB phosphorylated into CheB-P?

A

MCP is unbound due to methylation or lack of [ligand]. That means CheA-P. CheA-P phosphorylates CheB into CheB-P.
(CheB-P then demethylates MCP, and possibly causes ligand binding. If ligand does bind, run happens.)

41
Q

Chemotaxis: What 2 systems does “2 Component System” refer to?

A
  1. Sensor Kinase (ChA)

2. Response Regulator (CheB and CheY)

Microbiology (14 decks)

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