Life at a Cellular Level 3 Flashcards
What is the 1st law of energy changes?
Energy can be converted from one form to another but the total energy of the universe remains constant
What is the 2nd law of energy changes?
All energy transformations ultimately lead to more disorder in the universe (increase entropy)
What happens as usable energy decreases?
Unusable energy increases causing an increase in entropy
What is entropy?
A gauge of randomness or chaos within a closed system. As usable energy is irretrievably lost, disorganisation, randomness and chaos increase
What maintains order?
Cells
How do cells not defy the 2nd law if the maintain order?
- Cells do not live in isolation as hey are open systems, taking energy from the sun or food molecules to generate the order required for life
- The chemical reactions that generate the cell’s order produce heat, which is discharged into the surrounding environment and disorders it, so the total entropy increases
What 3 quantities can define Free energy?
- Enthalpy, H: heat released to surroundings
- Entropy, S: randomness/disorder
- Absolute temperature, T
What is the Gibbs free energy equation?
G=H-TS
How can spontaneous reactions occur?
-If a system gives up energy
And/or
-Becomes more random and increases entropy
Why will spontaneous energy changes have a negative value for change in free energy?
- A spontaneous process must decrease enthalpy and/or increase entropy
- ΔG = ΔH - TΔS
When is the only time spontaneous reactions will occur?
When a reaction releases energy
Why do reactions to generate proteins, DNA, cells, organs etc require reactions that have +ve ΔG?
Biological processes require more order rather than less
Why is energy coupling used?
To carry out thermodynamically unfavourable reactions
Whys do reactions not usually reach equilibrium.
- ΔG = 0 is incompatible with life
- Energy passes from the environment to the organism and back to the envirnoment
How is a dynamic steady state usually maintained/
By using a series of reactions
