Lecture 3: Energy and Enzymes Flashcards
importance of enzymes
- speed up rates of chemical reactions
phosphatas
- an enzyme that catalyzes the reaction of PO3 from protein
what is energy and its types
energy: capacity to do work
kinetic: motion
potential: stores energy
other forms: electrical, thermal, mechanical, chemical
- energy has to be converted cant be destroyed
thermodynamics
study of energy and transformations
1) energy can be transformed, but not created nor destroyed: total energy in a system must be constant
2) total disorder of a system and surroundings increases: entropy is a measure of disorder
for example: ice is in order, ice lattice structure VS +heat= water when it has disorder
forms of systems
CLOSED: exchanges energy but not matter with surroundings
OPEN: exchanges energy and matter (OUR CELLS!)
ISOLATED: exchanges no energy and no matter
what is disorder
random motion
what form of energy is most often converted into
thermal:
random motion of molecules
increased heat, increases disorder
to go from order to disorder
ORDER (no input of energy)
DISORDER (requires energy)
ORDER-DISORDER: spontaneous
DISORDER-ORDERL requires energy
room analogy:
disorder(messy room) takes energy to clean up (order), but it seems to get messy again without much effort
Spontaneous reactions
- chemical or physical reactions which occur without an input of energy from the surroundings
- change in enthalpy (change in PE) and entropy (measure of disorder) contributes
When do reactions tend to be more spontaneous
when products have less PE than reactants
measured based on two criteria:
1) PE: putting in energy
2) DISORDER: H2O is more disordered than ice (change in entropy)
endothermic vs exothermic
endo: reactions that absorb energy
- more PE in products, absorb energy
ex. ice melting (energy content of water is greater than ice)
exo: reactions that release energy
- less PE in products, release energy
ex. combustion (release of heat makes it spontaneous)
free energy
portion of energy in system available to do work
Change in free energy (Gibbs free energy) will tell you if its spontaneous or not measured using
1) enthalpy (change in PE)
2) entropy (change in order)
negative delta G= spontaneous reaction
Stable vs unstable energy
UNSTABLE
- more free energy
- less stable (can be harnessed)
- greater work capacity
STABLE
- less free energy
- more stable
- less work capacity
- release of free energy can be used for work
Equilibrium
- maximum stability
- equilibrium point is reached when reactants are converted back to products and converted back to reactants at equal rates
equilibrium in living systems
- living systems are open
- free energy is negative (spontaneous)
- organisms reach equilibrium (free energy=0) when they die
thermodynamics and life
- life is highly ordered suggested that it goes against second law (disorder and spontaneous)
- living things bring in energy and matter to generate order
- organisms release heat and byproducts to increase disorder too, increase in entropy
cells create order but still follow second law of thermodynamics
metabolic pathways and reactions
- exergonic reaction: where G is negative because products contain less free energy than reactants
- endergonic reaction: where G is positive because products contain more free energy than reactants
EXERGONIC IS NOT EXOTHERMIC
ENDERGONIC IS NOT ENDOTHERMIC
exergonic vs endergonic
exergonic: free energy is released, products have less energy so its -G and spontaneous
endergonic: free energy is gained, products have more so +G and its not spontaneous
catabolism vs anabolism
catabolism: exergonic, breaking down
anabolism: endergonic, building up
ATP storage and what process will release free energy
- ATP hydrolysis releases free energy that can be used as a source of energy for the cell
- mostly stored in mitochondria
ATP regeneration
- atp used in coupling reactions must be REPLENISHED
- done by linking atp synthesis to catabolic reactions
- atp cycle: continue breakdown and re-synthesis of atp
what type of reaction is hydrolysis of ATP
- exergonic reaction
- it can be coupled to make endergonic reactions proceed spontaneously
REQUIRES ENZYMES