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Metabolism
the sum of all anabolic and catabolic reactions in a cell, connected in a network of reaction pathways
Anabolic Reactions
make things, endergonic (use energy), takes energy from catabolic reactions
Catabolic Reactions
break things, exergonic (release energy), gives energy to anabolic reactions
Energy
Capacity to do work (potential and kinetic)
1st Law of Thermodynamics
Energy can be converted, but not created or destroyed
2nd Law of Thermodynamics
Entropy always increases, but we want it to decrease
Entropy
Disorder, things breaking or getting dispersed (does not mean lack of equilibrium!!!)
Free Energy (G)
is chemical energy available to do work and is expressed as the difference between enthalpy (total energy) and entropy
-Delta G
ā¢ Catabolic
ā¢ Lower G products
ā¢ Increase entropy
ā¢ Exergonic
ā¢ Spontaneous
+Delta G
ā¢ Anabolic
ā¢ Higher G products
ā¢ Decrease entropy
ā¢ Endergonic
ā¢ Non-spontaneous
Main Role of Enzymes
lower activation energy (the hump)
Enzymes
A type of protein where the function depends on the shape
Substrates
interact with enzymes at the active site, forming an enzyme-substrate complex with a close interaction through induced fit
Allosteric effectors
bind somewhere other than the active site (called the allosteric site) and alter the shape of the protein to either inhibit or activate enzyme function
Reaction coupling
Makes positive delta G reactions work by combining multiple reactions together (comines positive and negative reactions together to form a net negative reaction)
most common is hydrolysis and ATP
Enzyme Optima
The optimal conditions for an enzyme to work
Oxidation
Loss of electrons between molecules (looks like loosing an H)
Reduction
The gaining of electrons between molecules (looks like gaining an H)
Photosynthesis
transforms light energy into chemical energy
Light Reaction
energy carriers, generate high energy electrons (light dependent)
Dark Reaction
CO2 (light independent)
Stroma
Space outside chloroplasts (cytoplasm)
Thylakoid Membrane
hollow membrane disks (separator)
Thylakoid Lumen
Space inside disks
Photosystem 2
absorbs light
splits water (photolysis)
reduces PQ to PQH2 (gives electron to PQ)
Cytochrome Complex
Uses energy from e- to pump H+ creating an H gradient
Electrons reduce to PC
Photosystem 1
Absorbs light, exciting electrons
reduces ferredoxin, which delivers electrons to NADP+ reductase then to NADPH
ATP Synthase
Uses H+ gradient to power turning ADP + Pi into ATP
By Products of Photosynthesis
H+ and Oxygen
Calvin Cycle
turns CO2 into G3P in a never ending loop, involves both ATP and NADPH
Carbon Fixation
1st phase of the calvin cycle, CO2 (1C) is added to RuBP (5C) by rubisco which breaks turning into 2Ć 3C molecules
Reduction
2nd phase of the calvin cycle, 3C molecules reduced to form G3P (3C)
Regeneration
3rd phase of calvin cycle, 5x G3P are recycles into 3x RuBP
Use of G3P
used to synthesis carbohydrates, fatty acids, and amino acids
Carbohydrates
Sugar polymers used for fuel (ex, CH2O) can be monosaccharides, disaccharides, or polysaccharides