ATP Synthesis Flashcards
(21 cards)
What does exergonic mean ?
A reaction that releases free energy.
Gibbs free energy change (delta G) is negative
When can a reaction occur spontaneously?
When delta G is negative
What does endergonic mean ?
A reaction that absorbs free energy.
Delta G is positive
What does the 1st law of thermodynamics state ?
“For any physical or chemical change, the total amount of energy in the universe remains constant”
What is Gibbs free energy ?
The amount of energy in a system available to do work
Why do we need energy ?
- Muscle contraction- ATP binds to myosin heads, allowing them to detach from actin
- Active transport- ATP powers membrane proteins to move ions
- Heat production- when ATP is broken down, heat is released
- Building and repairing molecules
How do photographs obtain energy ?
By trapping light
How do chemotrophs obtain energy ?
By oxidation of food stuffs
Describe the extraction of energy from food
- Large molecules broken down into smaller units. No useful energy captured.
- Small molecules degraded into a few simple units that play a role in central metabolism. Some ATP generated.
- ATP produced from the complete oxidation of simple units by the final common pathways for oxidation of fuel.
Electron donor
Reducing agent that is oxidised
Electron acceptor
Oxidising agent that is reduced
What are dehydrogenases ?
They help oxidise compounds by removing 2H+ and 2e- and passing them to a carrier for later use
What are some examples of electron carriers ?
- NADH- delivers electrons to the ETC
- NADPH- carries electrons to the Calvin cycle
- FADH2- used in the generation of ATP
What is the currency of energy transfer in the cell ?
ATP
What is ATP made up of ?
- Adenine
- Ribose
- 3 phosphate groups
It contains 2 phosphoanydride bonds on its triphosphate unit.
What is ATP broken down into?
ADP + Pi + energy
How do we make ATP from ADP ?
- Oxidative phosphorylation- uses energy from electrons transferred through the ETC
- Substrate level phosphorylation- direct transfer of a phosphate group from a molecule to ADP, producing ATP
What are the 4 main functions of highly coordinated cellular activity ?
- Obtain energy
- Convert nutrients into own characteristic molecules
- Polymerise monomeric precursors
- Synthesise and degrade molecules required for special cellular functions
What are the classes of metabolic pathways ?
- Catabolic
- Anabolic
What is catabolic metabolism ?
Transform fuels into usable cellular energy.
Degradative
Produces ATP
Exergonic
What is anabolic metabolism ?
Utilise the useful energy formed by catabolism to generate complex structures from simple ones.
Synthetic
Requires ATP
Endergonic
