Principles of Bioenergetics

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  • Created by: LBCW0502
  • Created on: 29-11-17 16:04
What is the definition for energy?
The capacity to do work or produce a change. Energy exists in different forms (not created/destroyed)
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What are the uses of energy in living cells? (5)
Biosynthesis of proteins, DNA, RNA. Kinase catalysed phosphorylation of proteins to trigger conformational change. Super coiling of DNA. Specific reactions in carbohydrate, lipid and amino acid metabolism. Operation of active transport systems
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Define the bioenergetics of a reaction
The quantitative study of energy transductions (conversion of energy into other forms)
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Define the kinetics of a reaction
A branch of chemistry dealing with the rate of chemical reactions (factors influencing rate and comparisons in order of reaction)
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What is the definition of (Gibbs) free energy?
Expresses the amount of energy capable of doing work during a chemical reaction at constant temperature and pressure (H-TS)
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What is the difference between potential energy and kinetic energy?
Potential energy is stored whereas kinetic energy relates to motion of a body/particles in a system
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Give examples of potential energy
Glycogen, starch, glucose
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Give examples of kinetic energy
Movement, thermal energy/heat
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What is the first law of thermodynamics?
Principle of the conservation of energy (energy of an isolated system is constant)
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What is the second law of thermodynamics?
Universe always tends towards increasing disorder (increase in entropy - two systems with movement from hot to cold)
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Why is the first law of thermodynamics important in living systems?
First law - energy transferred e.g. free energy to ATP/energy rich compounds
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Why is the second law of thermodynamics important in living systems?
Second law - states entropy of universe increases/not entropy of reacting system. Short living organisms preserve internal order by taking free energy (nutrients/light) and return equal amount of energy to surroundings as heat/entropy
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Describe the features of an exergonic reaction
Negative free energy value, energy yielding, chemical energy in reactions > chemical energy in products, positive entropy
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Describe the features of an endergonic reaction
Positive free energy value, energy requiring, chemical energy in reactants < chemical energy in products, negative entropy
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Reversible reactions include which symbol?
Reversible arrow (equilibrium)
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Give examples of ATP as a energy carrier
Coupling exergonic and endergonic reactions etc
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Describe the importance of ATP as an energy carrier
-
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What is anabolism?
Synthetic reactions
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What is catabolism?
Degradative reactions
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What is enthalpy?
The heat content of a system (exothermic and endothermic)
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What is entropy?
Quantitative expression for the randomness or disorder of a system
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What are the units for free energy and enthalpy?
Joules/mole or calories/mole
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What are the units for entropy?
Joules/mole.Kelvin
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Is the free energy of a reacting system positive or negative for a spontaneous reaction?
Negative
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Why are cells isothermal systems?
The function at essentially constant temperature
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Why is heat flow not a source of energy for cells?
Heat can do work only as it passes to a zone or object at a lower temperature
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Describe the features of a reacting system at equilibrium?
Concentration of reactants and products are constant, rate of forward and reverse reactions are equal, not further net change occurs in system
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What is the equilibrium constant?
The concentration of reactants and products are equilibrium - Keq (equation involving number of molecules and molar concentrations of reactants and products)
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What is the standard free energy change?
The force of driving the system toward equilibrium under standard conditions (298 K, 1 M concentrations/101.3 kPa for gases or 1 atm
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How are hydrogen ions involved in the definition for standard free energy change?
Concentration of hydronium ions is 1 M or pH of 0 (pH and concentration of water/55.5 M are constant). Different standard state - reactions involving Mg/ 1mM
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What are standard transformed constants?
Written with a prime to distinguish them from untransformed constants
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How to Gibbs free energy defined using the equilibrium constant?
-RTlnKeq (alternative mathematical way of expressing equilibrium constant)
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What is the relationship between Gibbs free energy and the equilibrium constant?
Exponential. Small changes in free energy correspond to large changes in equilibrium constant
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Other cards in this set

Card 2

Front

What are the uses of energy in living cells? (5)

Back

Biosynthesis of proteins, DNA, RNA. Kinase catalysed phosphorylation of proteins to trigger conformational change. Super coiling of DNA. Specific reactions in carbohydrate, lipid and amino acid metabolism. Operation of active transport systems

Card 3

Front

Define the bioenergetics of a reaction

Back

Preview of the front of card 3

Card 4

Front

Define the kinetics of a reaction

Back

Preview of the front of card 4

Card 5

Front

What is the definition of (Gibbs) free energy?

Back

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