Fuels and Biofuels: Cellular Biosystems; Introduction to bioenergetics Flashcards
Many tasks that a cell performs requires energy, where do they get this from?
Deriving energy from the environment
What kind of energy favourability are most of the reactions in a cell? Why is this?
- Most are unfavourable
- This is because they require energy input
How do cells provide the energy for energetically unfavourable reactions?
By doing coupled reactions
Explain what a coupled reaction is
It is when a energetically favourable reaction (e.g. doesn’t need energy to react) energises the unfavourable reaction (takes the energy from this reaction)
Define energy
The capacity to do work
Define work
When an object has been moved against an opposing force
Where does the mitochondria get its energy from?
Carbohydrates and fats
What is the process called where cells harvest the chemical energy from food molecules? How is this energy extracted?
Cellular respiration, energy released as each bond is broken
What are conditions biological systems operate at?
Constant temperature of 37˚C and constant pressure of 1 atm
Under what conditions does a biochemical reaction occur spontaneously?
When the gibbs free energy
What is the name of the reaction that will occur spontaneously?
exergonic
What is the name of the reaction that requires energy to react?
endergonic
How do you calculate the gibbs free energy? Explain the variables
∆G = ∆H - T∆S ∆G = gibbs free energy ∆H = enthalpy change T = temperature of system ∆S = entropy change
What molecule provides the cell with energy to perform the endergonic reactions?
ATP
How is the energy from ATP extracted (chemical formula and ∆G)? How is this energy transferred?
ATP + H20 –> ADP + phosphate
∆G = -29kJ/mol
The phosphate group is transferred
What are the three main types of work in the cell?
Mechanical, transport and chemical
How does the phosphate transfer help with mechanical work?
Transfer of phosphate causes muscles proteins to change shape and pull on actin filaments therefore cell contracts
How does the phosphate transfer help with transport work?
The phosphate group attaches to the proteins in the membrane in a process called phosphorylating causing the protein to change shape and transport the molecule across
How does the phosphate transfer help with chemical work?
Phosphorylation of reactants provides energy to drive endergonic reactions
What is the total quantity of ATP in the human body (in mol)?
0.1
How many mols of ATP does our body use per day?
100-150
How many times a day is each ATP molecule recycled? Why is it this many times?
1000-1500 times a day
ATP cannot be stored as it is a spontaneous/exergonic reaction
