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Chem > Bioenergetics and Metabolism > Flashcards

Bioenergetics and Metabolism Flashcards

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1
Q

What is catabolism?

A

Breaking down bonds to release energy. They are generally oxidative reaction

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2
Q

What is anabolism?

A

Using energy to build molecules. Generally reductive

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3
Q

What’s the difference between a distinct and non-distinct pathway?

A

Distinct pathways share a lot of similar enzymes while non-distinct does not

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4
Q

Factors that control amount of enzymes?

A

-Transcriptions regulation (rate of mRNA synthesis)
-mRNA degradation
-translational regulation (rate of protein synthesis)
-Protein degradation

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5
Q

What factors that control the activity of an enzyme?

A

-Allostery (homo-activation/ inhibition, at a site other than the active site)
-Covalent modification (regulation of enzyme by covalent factors)
-Substrate availbility (homoallostry)
-Interaction with regulatory proteins
-Sequestration (localizing enzyme to subcellular compartments)

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6
Q

What is the difference between allosteric control and covalent modification?

A

Allosteric control involves a product in the pathway to feedback either immediately or further down the line to down regulate an enzyme while covalent modification involves an attachment of a certain group in order to activate or inactivate a certain enzyme

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7
Q

What are the general characteristics of second messengers?

A
  • Low amounts in the resting state
    -Regulated synthesis and destruction
  • Small and highly mobile
  • Non-protein but act through a protein
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8
Q

The production of second messengers alters…

A

the activity of the target enzymes in the cell

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9
Q

In what ways can ligand binding alter the receptor function?

A
  1. Ion channels can open or close
  2. Enzyme activity may be turned off or on
  3. The ability to bind/ interact with other proteins may be altered
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10
Q

What hormones are GPCR’s?

A

Glucagon and epinephrine

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11
Q

Describe the process of signal transduction via GPCR’s and second messengers?

A
  1. Hormone binds to the receptor and activates the G protein
  2. Activated G protein exchanges GTP with GDP and alpha subunit is ready for a cellular response
  3. GAlpha- GTP binds adenlyly cyclase which converts ATP into cAMP
  4. Camp binds to the inactive protein kinase A. 2 cAMP’s bind to each regulatory unit (allosteric site) –> activating PKA
  5. The catalytic unit of PKA then phosphorylates a target enzyme inducing a cellular response
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12
Q

What are the “off switches” in signal transduction?

A

G Protein - Intrinsic GTPase activity converts GTP back to GDP
cAMP - is converted into AMP by enzyme phosphodiesterase with H2O
Target enzyme - is dephosphorylated with phosphatase

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13
Q

What is enthalpy

A

energy in a system

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14
Q

what is entropy

A

randomness in a system

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15
Q

Negative DeltaG means..

A

-reaction is exergonic
-energy is released
-Rxn proceeds fwd spontaneous

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16
Q

Positive DeltaG means

A

-Rxn us endergonic
-energy is absorbed
-Rxn does not occur in forward direction

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17
Q

What does delta G tell us

A

force that is required to get to equilibrium, magnitude and sense of direction

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18
Q

What does Delta G not tell us

A

the rate of reaction

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19
Q

What are coupled reactions?

A

Energy released by an exergonic reaction that can drive an endergonic reaction

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20
Q

Coupled reaction can only occur if….

A

they are linked by a common intermediate

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21
Q

what is direct coupling?

A

When an enzyme can catalyze 2 reactions

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22
Q

Give an example of direct coupling

A

Phosphorylated glucose can be forced to proceed with ATP. The enzyme hexokinase couples the reaction but excluded water

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23
Q

What is indirect coupling?

A

Two consecutive enzymes can catalyze reactions

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24
Q

How much energy does a phosphoanhydride bond release?

A

-30KJ/Mol

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25
Q

how much energy does does a phosphoester bond release?

A

-16kj/mol

26
Q

ATP is a metastable compound, what does this mean?

A

it means that it is thermodynamically (releases a lot of energy when broken apart) stable and kinetically stable (needs a lot of activation energy)

27
Q

what causes ATP to be a metastable compound?

A

-hydrolysis cause a relief of negative charges
-There is resonance stabilization of Pi
- Solvation effect, larger water shell is formed with ADP than ATP
-Increased entropy

28
Q

How would a decrease in pH change the DeltaG of a reaction?

A

more positive

29
Q

How would a increase in pH change the DeltaG of a reaction?

A

more negative

30
Q

What is the true substrate for most enzymes?

A

MgATP

31
Q

Define phosphorylation

A

Adding a phosphoryl group

32
Q

define phosphate transfer?

A

transferring phosphoryl group form one molecule to another

33
Q

define substrate level phosphorylation

A

A phosphate transfer that generates a NTP

34
Q

what is a phosphagen?

A

a phosphoamide with higher group transfer potential than ATP

35
Q

Why does the hydrolysis of phosphocreatine release so much energy?

A

Resonance stabilization of both the Pi and the creatine

36
Q

What makes thioesters have large free energies

A

Release of the CoA group with water forms Acetic acid which has resonance stabilization when deprotonated

37
Q

What is a acyl group

A

removal of one or more hydroxyl groups from an oxoacid (carboxylic acid) it contain a double bond to oxygen and an alkyl group

38
Q

What are the different ways ATP can form?

A
  1. Substrate level phosphorlyation - Direct transfer of a phosphate from a high energy compond to a nucleoside diphosphate
  2. Oxidative phosphorylation - Phosphorylation of ADP to ATP coupled to the electron transport chain from a *substrate to molecular oxygen *
  3. Photophosphorylation is the phosphorylation of ADP to ATP coupled to the light dependent transfer of electron in a photosynthetic cell
  4. Adenylate Kinase - Reaction can synthesize ATP from 2ADP

  • Subtrate such as NADH and FADH2
    *
39
Q

What reaction does adenylate kinase catalyze?

A

ADP + ADP <–> ATP + AMP

40
Q

Why is the reaction done with adenylate kinase important?

A

-Done in muscle without oxygen to produce ATP

41
Q

How can tou produce ATP from AMP

A

AMP from pyrophosphate cleavage of ATP can converted to ADP vid ADK
ADP can then make ATP

42
Q

What enzyme does transphosphorylations?

A

Nucloetide diphosphate kinase

43
Q

What is a transphophorylation reaction?

A

Between nucleotide and can occur in all cell types

NTP + NDP (dNDP) <–> NDP + NTP

44
Q

What are the 3 stages of aerobic catabolism?

A
  1. Breakdown of the carbon backbone to forn NADH and FADH2 –> Acetyl CoA
  2. Citric acid cycle will use acetyl CoA to yeild alot of CO2 and reduced cofactors
  3. Oxy phor will yeild alot of ATP from NADH and FADH2
45
Q

What is a reducing agent

A

Electron donor, becomes oxized
Aka reductant

46
Q

What is a oxidizing agent

A

becomes reduced, recieves electrons
Oxidant

47
Q

what is the formula for the oxizing states of carbon

A

of valence electrons on atom - (# of lone pair + assigned electrons)

48
Q

How can electrons be electrons be transferred?

A
  1. Transfer of hydrogen atom
  2. Transfer of hydride atom
  3. Directly as electrons
  4. Thru a direct combo with oxygen
49
Q

Explain what oxygenase does?

A

It’s an enzyme that oxidizes a substrate by transferring an O2 to it.

Explaination: because the oxygen is more electronegative once on a compound the oxygen will pull the electrons

50
Q

What does oxidase do?

A

Oxidase catalyzes ox-red reactions to make O2 the electron acceptor

51
Q

What does dehydrogenase do?

A

It transfers two hydrogen atoms

52
Q

What does reduction potential mean?

A

The transfer of electrons based on a molecules affinity for it

53
Q

In biological systems oxidation is synonymous with…

A

Dehydrogenation by dehydrogenase

54
Q

What is a cosubstrate

A

Behaves like a substrate

55
Q

What is a coenzyme

A

Group that is tightly bond to enzyme

56
Q

How can you tell the difference between NAD+ and NADH

A

NADH can only be seen in the visible light range, putting under a spectrometer. Mix NAD+ with lactate which will convert to NADH and pyruvate

57
Q

What can an electrochemical cell tell you?

A

Voltage will indicate flow of electrons

58
Q

The more positive E’*…

A

The higher affinity for the oxidized form for e-

59
Q

Electron flow spontaneously from compounds with __________ to compounds with ___________

A

Low reduction potentials, high reduction potentials

60
Q

For electron transfer, delta E must be what?

A

Positive

Chem (9 decks)

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