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Cells to Organisms - Lectures > Lecture 3. Energy, Transport and Scavenging Bacteria > Flashcards

Lecture 3. Energy, Transport and Scavenging Bacteria Flashcards

1
Q

What are some things in which bacteria spend energy on ?

A
  1. Manufacturing
  2. Transport
  3. Surveillance
  4. Waste Management
  5. Energy Production
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2
Q

What is the bacteria’s currency ?

A

Adenosine Triphosphate

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3
Q

What are some things that bacteria do ?

A
  1. Self-monitoring
  2. Monitoring others
  3. Motility
  4. Regulation
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4
Q

What do bacteria make decisions in response to ?

A

Their environment

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5
Q

How does E. coli bacteria produce the energy currency ATP ?

A

F-ATP synthase

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6
Q

What is the structure of E.coli F-ATP synthase ?

A

Membrane bound protein with a rotating head

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7
Q

What causes the system (F-ATP synthase) to rotate ?

A

The large chemiosmotic potential of protons in the periplasm which are unable to pass on their own across the cytoplasmic membrane must pass through the motor complex causing rotation

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8
Q

What does the rotation of the F-ATP synthase cause ?

A

ADP and pyrophosphate to be physically forced together so they bond and form ATP

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9
Q

What powers the flagellar based systems ?

A

The proton motive force coming from the rotation of F-ATP synthase

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10
Q

How do E. coli produce ATP ?

A

Using F-ATP synthase

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11
Q

What complex possesses a rotating head ?

A

Membrane bound protein

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12
Q

What do protons in the periplasm have ?

A

Large chemiosmotic potential

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13
Q

What causes the membrane bound protein complex to rotate ?

A

The passage of protons from the periplasm

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14
Q

What happens as a result of the rotation of the head of the membrane bound protein ?

A

ADP and pyrophosphate are physically forced together so that they bond to form ATP

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15
Q

Where does the energy to rotate the membrane bound protein complex head come from ?

A

Central metabolism with the breakdown of carbon sources using ATP in oxidation phosphorylation

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16
Q

What are the carbon atoms released from oxidation phosphorylation used for ?

A

Creating cellular components

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17
Q

What does the oxidation phosphorylation process also involve ?

A

Electron transport chain

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18
Q

How are substrates transported across the membrane into the interior of the cell ?

A

ATP being used to pump hydrogen ions across the inner membrane into the periplasm creating an ion gradient

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19
Q

What does uniport mean ?

A

Only one molecule is moving

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20
Q

What is the least common method of transmembrane transport ?

A

Facilitated diffusion

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21
Q

What is an example of facilitated diffusion ?

A

E. coli glycerol uniporter

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22
Q

What does the E.coli glycerol uniporter system utilise ?

A

A membrane embedded protein (facilitator) to move the substrate molecule across the membrane

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23
Q

What does the E.coli glycerol uniporter not use ?

A

Energy which means it cannot move the substrate against a concentration gradient

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24
Q

What type of system is facilitated diffusion ?

A

Passive

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25
Q

What does the symport ion coupled system require ?

A

Energy and the substrate to have an ion partner which passes through the symport protein in the same direction in a one for one co-transport fashion

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26
Q

What is a good example of the symport ion couple system ?

A

The Lac permease

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27
Q

What is the lac permease responsible for ?

A

Transporting lactose

28
Q

What do antiport systems require ?

A

Energy and a counter ion

29
Q

What direction do the substrate and counter ion move in ?

A

Opposite directions with antiport systems

30
Q

How can antiport systems be used ?

A

They exchange and accumulated compound for an excreted one and can be harnessed to create a chemiomotic circuit

31
Q

What is bacteria’s favorite carbon source ?

A

Glucose

32
Q

Why does bacteria prefer glucose ?

A

Easiest to metabolise and generate the most amount of energy

33
Q

What is the function of LacY permease ?

A

A symport transporter

34
Q

What operon is LacY permease part of ?

A

lacZYA

35
Q

What is the structure of permease of LacY permease ?

A

A membrane embedded protein with 12 transmembrane regions. It has loops on both the periplasmic and cytoplasmic sides of the membrane

36
Q

What is LacZ protein?

A

A beta-galactoside which cleaves disaccharide into glucose and galactose

37
Q

What does lacA gene code for ?

A

Beta-galactoside transacetylase

38
Q

Where is lacl repressor found ?

A

Upstream of the repressor

39
Q

What is the function of lacl repressor ?

A

Regulates the downstream operonic promoter resulting in the expression of the operonic genes

40
Q

What are the lac operon and the lacl repressor responsible for ?

A

Transport and metabolism of lactose in the cell at the appropriate time

41
Q

What happens when there is no lactose in the cell ?

A

The tetrameric lac repressor binds to operator sites in the operonic promoter and shuts down transcription of the operonic genes

42
Q

What happens when lactose is present ?

A

The structure of lacl tretramer changes, causing it to detach from the operator sites in DNA

43
Q

What does the removal of lacl allow ?

A

The lacZYA to be transcribed from the de-repressed transcription promoter

44
Q

What must happen in order to give the promoter full power ?

A

A transcription factor - dimeric CRP protein must bind

45
Q

What are the conditions surrounding dimeric CRP binding ?

A

It only binds to DNA when it has first bound the second messenger cAMP

46
Q

What only occurs when cAMP is present ?

A

Binding and de-repression

47
Q

What does the cAMP-CRP complex bind to ?

A

A specific consensus DNA sequence contained within the operator site upstream of lacZYA

48
Q

What controls the production of cAMP ?

A

Glucose

49
Q

What is the function of cAMP ?

A

Controls large numbers of genes and is an important second messenger

50
Q

When glucose is high, what happens to EIIA ?

A

It is mainly unphosphorylated and adenine cyclase is inactive

51
Q

When glucose is low, what happens to EIIA ?

A

Phosphorylated EIIA accumulates and this activates membrane bound adenylate cyclase

52
Q

What does adenylate cyclase do ?

A

Converts ATP into cAMP

53
Q

What does dephosphorylated EIIA inhibit ?

A

The lac permease and blocks lactose uptake

54
Q

What does no cAMP-CRP result in ?

A

The activation of lac transcription

55
Q

What does the lactose sugar molecule enter ?

A

The lacY binding pocket

56
Q

What blocks the lacY binding pocket ?

A

Anionic glutamic acid and the cationic lysine

57
Q

What draws protons into the binding pocket ?

A

The protein gradient on the periplasmic side of the membrane creates a protein motive force

58
Q

What breaks the salt bridge ?

A

The positive charge on the proton balances the negative charge on the glutamic acid

59
Q

What does cationic lysine do ?

A

Temporarily forms a new salt bridge with anionic aspartic acid which opens the door for the lactose sugar molecule and the proton to move across the membrane into the cytoplasm

60
Q

How does the original salt bridge reform ?

A

The lysine has a higher affinity for salt bridge formation with glutamic acid rather than aspartic acid

61
Q

What is the PTS system used for ?

A

Used by bacteria for sugar uptake where the source of energy is PEP

62
Q

What is PEP ?

A

Phosphoenolpyruvate

63
Q

What is PEP catabolised into ?

A

Pyruvate phosphorylating enzyme I

64
Q

What does enzyme I phosphorylates ?

A

The heat stable protein

65
Q

What does the heat stable protein do ?

A

Phosphorylates enzyme IIAGc until the incoming sugar is phosphorylated as it passes through the membrane integral permease which has now been converted to glucose-6-phosphate

66
Q

What prevents the transporter from recognising the substrate again ?

A

The transfer of phosphate group to substrate once it has been imported through the membrane transporter

67
Q

What does the PTS system act as ?

A

A regulator of other sugar uptake systems

Cells to Organisms - Lectures (36 decks)

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