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Biochemistry 1 BB10003 > lecture 9 - bioenergetics > Flashcards

lecture 9 - bioenergetics Flashcards

1
Q

isolated system

A

cannot exchange energy or matter with its surroundings

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2
Q

closed system

A

can exchange energy in the form of heat or work

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3
Q

open system

A

can exchange both energy and matter with its surroundings

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4
Q

What is thermodynamics

A

concerned with the direction/thermodynamic feasibility of the processes

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5
Q

What is kinetics

A

concerned with the rate of processes

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6
Q

what are bioenergetics

A

how living systems make use of free energy

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7
Q

What is a system?

A

matter at a given temp, pressure and volume. part of the universe under study

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8
Q

what is the surroundings?

A

entire universe excluding the system

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9
Q

what is a process?

A

any change that occurs in the system

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10
Q

what is the difference between transfer of heat (q) and work done (w)?

A
  • transfer of heat (q) to or from system
  • work done (w) by the system on its surroundings or work done by the system
q = energy transfer by random motion 
w = energy transfer by organised motion
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11
Q

what does all energy end up as in the end?

A

All energy will eventually end up as heat energy

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12
Q

what is the first law of thermodynamics?

A

energy cannot be created or destroyed, only transported…

…implies that the reaction can occur in either direction

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13
Q

what is a state function?

A

depends only on the current properties or state of the system, not how the system reached the state

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14
Q

Reaction for the change in enthalpy

A

delta H = delta U + P * delta V

change in enthalpy = change in energy + pressure * change in Volume

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15
Q

what is the second law of thermodynamics?

A

Any spontaneous process must cause the entropy of the universe to increase

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16
Q

What is entropy?

A

Measures the degree of disorder or randomness of a system

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17
Q

What factors are unchanging at equilibrium?

A

temperature and total energy are unchanging at equilibrium

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18
Q

What is the equation for Gibbs free energy?And what are the units?NEED TO LEARN

A

Delta G = Delta H - T*Delta S

Delta g = KJ/mol
Delta H = KJ/mol
T = Kelvin
Delta S = J/mol

19
Q

What is a perturbed system?

A

by adding more molecules or by changing temp, then the system is no longer at equilibrium. The macroscopic variables will respond to the changes until the system reaches a new equilibrium.

20
Q

What happens when you differentiate Delta G ?

A

Get minimum and maximum points on a graph.

21
Q

what happens at minimum points?

A

small fluctuations in the system parameters will increase G

22
Q

What is the free energy change of reaction?

A

total free energy or reactants go to total free energy of products

23
Q

Delta G > 0

A

Forward process is energetically unfavourable

24
Q

Delta G = 0

A

system is at equilibrium, no further change

25
Q

delta G < 0

A

forward process is energetically favourable

26
Q

What is an exergonic reaction?

A

Energy is released by the surroundings

27
Q

what is an endergonic reaction?

A

Energy is absorbed by the surroundings

28
Q

How do you make a reaction proceed in the correct direction

A
  • alter the concentrations
  • couple the reaction; couple a positive data G value to on that has a negative Delta G value. this would mean that Delta G could be < 0
29
Q

What is the free energy and concentration equation? The alternative Delta G equation?
NEED TO LEARN

A

Delta G^o + RTln ( products/ reactants)

30
Q

What does the standard free energy change mean/ represent?

A

Denotes that reactants and products are all at 1M concentration, temperature at 298k and pressure at 1 atmosphere

31
Q

What is the third Delta G equation? NEED TO LEARN

A

Delta G = - RTlnKeq

32
Q

What is the relationship between Delta G ^o and Keq?

A

Inverse basically.

Delta G <0 then Keq >1

delta G >0 then Keq<1

33
Q

What properties of ATP make it the major energy currency of biochemical processes

A
  1. relief of electrostatic repulsion when terminal phosphate bond is hydrolysed – there is very little tendency for ADP and Pi to re-join as negative charges repel;
  2. inorganic phosphate (Pi) undergoes stabilisation as a resonance hybrid
  3. greater degree of solvation of the products ADP and Pi relative to ATP, further stabilising products relative to reactants.
  4. two reactant molecules form 3 product molecules – more ways to distribute translational and rotational energy among 3 molecules – makes positive contribution to entropy.
34
Q

what are standard quantities in Biochemistry?

A

conditions of defined molecular state used as a reference for reporting free energy values

35
Q

what is the normal coupling in a Metabolic pathway?

A
  • Endergonic reaction to an exergonic reaction, create a more negative delta G
36
Q

what is ATP and why is it used?

A

common intermediate in the mainstream of energy . Can convert glucose into glucose - 6 - phosphate, coupling ATP hydrolysis can allow the reaction to be thermodynamically favourable

37
Q

The thermodynamics and kinetics regarding ATP

A

ATP is thermodynamically unstable- which mean it can happen spontaneously. However because is it kinetically stable , it means it is very slow. Therefore enzymes are needed to catalyse the hydrolysis of the reaction

38
Q

How can phosphates be transferred?

A

cannily be transferred from high energy to low energy compounds

39
Q

Where is ATP positioned in the thermodynamic scale?

A

In the middle of the phosphate components

40
Q

What is the enthalpy of a system?

A

tells us how much heat and work was added/ removed

41
Q

What does delta G ^ o represent?

A

Its a constant for a given reaction and tells up the equilibrium constant

42
Q

What does Delta G represent?

A

Represents extra free energy change

43
Q

What happens to Keq when Delta G ^o is large and negative

A

Keq is very large

44
Q

What happens to Keq when Delta G^o is large and positive?

A

Keq is very small

Biochemistry 1 BB10003 (18 decks)

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