Bioenergetics 1 - Life & Energy (incl. Bomb Calorimeter) Flashcards
Ultimately, why do we breathe?
So that we can produce energy in the form of ATP!
EVERY cell has the capacity for self-………… and self-…………… .
Replication, assembly.
What is the bioenergetics definition of energy?
How living systems capture, transform and use energy to perform work and stay alive.
Name some forms of biological work.
Synthetic, mechanical, concentration (e.g. active transport), electrical, heat, bioluminescent.
Hydrocarbons + oxygen =
CH4 + 2O2 =
Water + carbon dioxide + energy.
H2O + CO2 + energy.
Dietery fuel / carbohydrates and lipids + oxygen =
C6H12O6 + O2 =
Carbon dioxide + water + energy.
6CO2 + H2O + energy.
How would a biochemist define energy?
Usually, as the chemica energy that is exchanged in a reaction, e.g.:
ATP to ADP, NADH to NAD+ or Glucose to CO2 and H2O.
What is the activation energy of a reaction?
How much energy is required for the reaction to take place.
What effect does an catalyst have on the activation energy of a reaction?
A catalyst lowers the activation energy of a reaction.
Are living creatures efficient in their chemical reactions?
No!
True or false? Reactions in living creatures always have a start and an end point.
False.
Why is non-equilibrium thermodynamics used in living organisms?
Non-equilibrium thermodynamics are used in living organisms because they are very inefficient and the reactions do not have a start and end point.
Why can’t equilibrium thermodynamics be used in living organisms?
Reactions in living organisms do not have start and end points.
Define a ‘system’.
The matter within a defined region of space.
What is an open system? Give an example.
In open systems, matter AND energy can be exchanged between the system and its surroundings.
e.g. ocean.
What is a closed system? Give an example.
In a closed system, energy can enter and leave the system into the surroundings, but matter is trapped within the system.
e.g. greenhouse.
What is an isolated system? Give an example.
An isolated system is one where both energy and matter are trapped inside the system and cannot leave.
e.g. gas cylinder.
What is the concept of equilibrium thermodynamics?
‘Man-made machines are devices which allow energy to be transformed from one type to another’.
What is this concept called?:
‘Man-made machines are devices which allow energy to be transformed from one type to another’.
Equilibrium thermodynamics.
What is the First Law of Thermodynamics?
Energy within a system is conserved, it can be converted from one form to another but it cannot be created or destroyed.
If a reaction occurs in a well-insulated container, there is no ……………… exchange.
If a piston is prevented from moving, there is no …………….. done.
This is the principle of the …………… …………….. .
Heat, work, bomb calorimeter.
ΔE = Q-W.
What does this reaction show?
Change in energy = heat added to the system - work done.
If there is no heat exchange and Q = 0. What does ΔE = ?
-W.
If no work is done and W=0, what is ΔE?
Q.
Which instrument is the MOST DIRECT way of measuring the energy content of foodstuffs and metabolites?
The bomb calorimeter.
In a bomb calorimeter, the energy produced by combusting or oxidising a substrate can be measured as…?
A change in internal energy, ΔE.
In exothermic reactions, is ΔE always positive or always negative?
In exothermic reactions, ΔE is ALWAYS negative.
What is the enthalpy of a system?
A measurement of heat change during a reaction at a constant pressure and volume.
Why is enthalpy used for changes in internal energy in living systems?
The temperature difference between the system and the surroundings are small.
What does this equation calculate?
ΔE = ΔH - PΔV
where H is heat, P is pressure and V is volume.
Enthalpy of a system.
If, in biology,
If, in biology, we assume pressure and volume to be constant, what does this mean for the following equation?:
ΔE = ΔH - PΔV
If we assume P and ΔV to be constant, then ΔH = ΔE.
What does ΔH mean?
The enthalpy of ‘heat combustion’.
What units does ΔH, enthalpy of heat combustion have?
Joules.
When glucose is completely burned in a bomb calorimeter, the energy released is -2,810kJmol-1, whereas when a fatty acid is burned -9,950kJmol-1 is released. What does this tell us about glucose vs. fatty acids?
Fatty acids are better for storing energy than glucose because they can hold more energy per mole.
Outline how a bomb calorimeter can be used to calculate the energy produced in a reaction.
- Combust a fixed quantity of substance one and measure ΔH1.
- Repeat for ΔH2 in a separate reaction.
- ΔH? = ΔH1 - ΔH2.
Make sure to account for how many molecules of product are made for each molecule of reactant!
Which is more efficient - sprinters using ‘fast’ muscles to convert glucose to lactate anaerobically, or marathon runners using ‘slow’ muscles to convert glucose and fat to carbon dioxide and water aerobically?
Marathon runners.
True or false? In extreme circumstances, heart muscle can convert fatty acids to carbon dioxide and water in aerobic respiration.
True.
How efficient is lactobacillus in converting glucose to lactate?
a. 1.8%
b. 18%
c. 81%.
1.8%!
How efficient is skeletal muscle in converting glucose to lactate?
a. 1.8%
b. 18%
c. 81%.
1.8%!
