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Energy
- Capacity to do work
- can take many forms
- -mechanical, heat, electric current, light
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Kinetic Energy
The energy of motion
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potential Energy
- stored energy
- -energy thats stored in chemical bonds & can be transferred from one molecule to another by way of electrons
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Kilocalories and calories
- what heat energy is measured in
- Heat energy is what most forms of energy can be converted to
- 1 kilocalorie (kcal)= 1000 calories
calorie-amount of heat required to raise temp of water by 1 deg. C.
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Oxidation
LEO
loss of electrons
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Reduction
GER
gain of electrons
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Redox reactions
coupled to each other
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First Law of Thermodynamics
- energy cant be created or destroyed
- -can only be converted from one form to another
- ex. sunlight energy --> chemical energy (by photosynthesis)
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Second Law of Thermodynamics & Entropy
- disorder is more likely than order
- -entropy is always increasing
- -the more order, the more potential energy
- ENTROPY-disorder in universal
- potential=mechanical
- entropy=disorder
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Free Energy & Enthalpy
- energy available to do work
- -denoted by symbol G (Gibbs free energy)
- Enthalpy
-energy contained in a molecule's chemical bonds - ""=stored away - (entropy x temp.)
- free energy = enthalpy - (entropy x temp.)
- G= H-TS
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When products contain more free energy than reactants...
-^G (triangle) is positive
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when reactants contain more freee energy than products...
-^G is negative
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Activation Energy
- extra energy needed to get a reaction started
- -destabilizes existing chemical bonds
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Catalysts
substances that lower the activation energy of a reation
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ATP
- adenosine triphosphatethe energy currency of cells
- ATP structure:-ribose, a 5-carbon sugar
- -adenine
- -3 phosphates
- it stores energy in the bonds between phosphates
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ADP and Pi
- when bond btwn phosphates is broken:
- ATP-->ADP + Pi (energy is released)
- ADP- adenosine diphosphate
- Pi-
inorganic phosphate - (this reaction is reversible)
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Enzymes
- molecules that catalyze reactions in living cells
- -most are protiens
- -lower the activation energy required for a reaction
- -not changed or consumed by the reaction
- -interact with substrates
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Substrate
- molecule that will undergo a reaction
- *binding of an enzyme to a substrate causes the enzyme to change shape, producing a better induced fit btwn the molecules
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Active site
region of the enzyme that binds to the substrate
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What affects an enzyme
- enzyme function affected by its environment
- -factors that can change an enzymes 3D shape can change its function they are:
- pH- enzyme prefer 6-8
- temp- temp. increase, so does reaction. too far above opt. temp can denature enzyme
- regulatory molecules-
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Inhibitors
molecules that bind to an enzyme to decrease enzyme activity
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Competitive inhibitors
compete with the substrate for binding to the same active site
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noncompetitive inhibitors
bind to sites other than the enzyme's active site
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Metabolism
all chemical reactions occuring in an organism
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Anabolism
chemical reactions that expend energy to make new chemical bonds
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Catabolism
chemical reactions that harvest energy when bonds are broken
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cofactors
- usually metal ions found in the active site participating in catalysis.
- -helps in proper enzymatic activity
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coenzymes
- nonprotien organic molecules often used as an electron donor or acceptor in a redox reaction.
- -help in proper enzymatic activity
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Biochemical pathways
- series of reactions in which the product of one reaction becomes the substrate for the next reaction.
- -regulated by feedback inhibition
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Feedback inhibition
the end product of the pathway is an inhibitor of an earlier enzyme in the pathway
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autotrophs
able to produce their own organic molecules through photosynthesis
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heterotrophs
live on organic compounds produced by other organism
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cellular respiration
- used by all organisms to extract energy from organic molecules
- -series of reactions that are oxidations, dehydrogenations
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dehydrogentation
- lost electrons are accompanied by hydrogen
- what is actually lost is a hydrogen atom (1 elec. 1 proton)
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NAD+
during redox reactions, electrons carry energy from one molecule to another.
- NAD+ is a electron carrier
- it accepts 2 electrons and 2 proton to become NADH
- this reaction is reversible
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Aerobic Respiration
final electron receptor is oxygen (O2)
- C6H12O6+6O2-->6CO2+6H2O
- glucose + oxygen-->carbon dioxide + water
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Anaerobic respiration
final electron acceptor is an inorganic molecule (not O2)
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Fermentation
final electron acceptor is an organic molecule
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Goal of respiration:
- to produce ATP
- -energy is released from oxidation reaction in form of electrons
- -elec. are shuttled by electron carriers (NAD+) to electron transport chain
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elec. energy is converted to ATP at the elec. transport chain
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Cells are able to make ATP via:
-substrate-level phosphorylation: transfering a phosphate directly to ADP from another molecule
and
oxidative phosphorylation: use of ATP synthase and envery derived from a proton (H+) gradient to make ATP
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Oxidation of Glucose steps:
- glycolysis
- pyruvate oxidation
- krebs cycle
- electron transport chain
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Glycolysis
- converts glucose to pyruvate
- occurs in cytoplasm
- 1 glucose = 2 pyruvate
- products of glycolysis:
- 2NADH
- 2 ATP
- 2 pyruvate
- for glycolysis to cont. :
NADH be recycled to NAD+ by: aerobic (when O2 is available as final elec. accept.) - fermentation (when oxy. isnt avail. & organic molecule is final elec. accept.
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Fate of pyruvate depends on...
oxygen availability.
with O2: pyruvate is oxidized to acetyl-CoA & enters Kerbs cycle
w/out O2: pyruvate reduced to oxidize NADH back to NAD+
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