lecture 2: energy Flashcards
(30 cards)
Forms of energy in life? (5)
- Radiant energy (photosynthesis)
- Chemical energy
- Thermal energy (Heat)
- Mechanical energy (movement)
- Electrical energy
What happens to energy in the ecosystem? (3)
- Energy = transformed as it flows through ecosystems
- Enters as radiant (sun) energy and exists as thermal energy
- Subjected to laws of thermodynamics in the organisms
First law of thermodynamics?
Energy can be transformed or transferred but can not be destroyed or created
Second law of thermodynamics?
As energy is transformed —> some converted to unusable energy (heat) —> as entropy of the system increase
- Entropy of the universe is always increasing
Why do organisms require energy?
Use energy to power biological work
3 kinds of biological work that organisms carry out
- Synthesizing molecules to build complex structures and to reproduce
- Movement of body, cells and substances within cells
- Transport of chemicals across the cell membrane
What is energy coupling?
- Biological work is accomplished by coupling a SPONTANEOUS process to a NON SPONTANEOUS process = OVERALL SPONTANEOUS process
- Most energy coupling relies on ATP hydrolysis
What is a spontenous process? Examples?
- Downhill reaction
- Happens without added energy
- Gravity, diffusion, chemical reactions
What makes a process spontaneous (2 factors)?
- Change in POTENTIAL ENERGY
- Spontaneous if goes from high potential energy to LOW potential energy - Change in the degree of order (ENTROPY)
- Spontaneous if goes from high order (low entropy) to low order (more entropy)
Spontaneous reactions want to increase the entropy of the universe
Gibbs Free-Energy Change (∆G) takes into account both…
the changes of potential energy and the changes in disorder
How do you interpret ∆G?
- ∆G = spontaneous/exergonic process
+ ∆G = non spontaneous/endergonic process
∆G = 0: process is at EQ
What does ∆G represent in a spontaneous/exergonic process?
Energy available to carry out work when a process occurs (goes from high G to low G in a graph)
What does ∆G represent in a non spontaneous/endergonic process?
Energy required to carry out a process (goes from low G to high G)
2 Characteristics of spontaneous processes
- Can be used to carry out work
- Proceed towards equilibrium (∆G = 0)
What happens at the end if a spontaneous system is carried out in a CLOSED system?
Work will eventually stop when the process reaches equilibrium
What is dynamic equilibrium?
Forward process occurs at the same rate as the reverse process
Organisms are open or closed systems?
Open
What happens if a spontaneous process is carried out in an open system?
- Process does not reach equilibrium and work always continues
- Reactants are products are maintained at a STEADY-STATE (stable) concentrations and NOT at EQ concentrations
- Process remains sponteneous
What is ATP + use + characteristics?
- Adenosine triphosphate: energy currency
- Used for most work in the cell vis energy coupling
- ATP has high chemical energy —> so ATP hydrolysis is highly spontaneous
ATP Structure (3)
(RNA nucleotide, building blocks for RNA)
1. Nitrogenous base
2. Ribose sugar
3. Three phosphates
What is the hydrolysis of ATP?
ATP —> ADP + P
- Hydrolysis (break) of bond between the 2 outermost phosphate groups —> form ADP (with 2 phosphates) + P (1 inorganic phosphate)
- Highly spontaneous
Why is hydrolysis of ATP highly exergonic? (2)
- Goes from high potential energy to lower potential energy when more stable ADP and P are formed from ATP
- Entropy of product molecules is higher than reactants (ADP and P vs only ATP) —> more molecules in products
Why does ATP have high potential energy making it less stable?
3 phosphates with negative charges = high repulsion
How is ATP hydrolysis used in cells?
- ATP hydrolysis produces energy as heat, but cells use the energy to make things happen
- ATP hydrolysis is used to alter molecules in order to perform synthesis, transport and mechanical work
