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proteins (and RNA)
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organic catalysts that lower the required activation energy to get reactants to products
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facilitate chemical reactions:
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~ increase rate of reaction without being consumed
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~ reduce activation energy
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~ do not change free energy released or required
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substrate:
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~ reactant which binds to enzyme
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~ enzyme-substrate complex: temporary association
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product:
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~ end result of reaction
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active site:
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~ enzyme's catalytic site: substrate fits into actives site
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changes in pH:
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~ adds or removes H+
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~ disrupts bond, disrupts 3D shape
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~ disrupts attractions between charged amino acids
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~ affects 2' and 3' structure
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~ denatures protein
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cofactors:
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coenzymes:
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small, inorganic compounds and ions
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organic compounds
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binds with enzyme
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bind to enzymes near active site
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Mg, K, Ca, Zn, Fe
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vitamins (NAD, FAD, Coenzyme A)
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conformational changes by regulatory molecules
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inhibitors: keeps enzyme in inactive form
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activators: keeps enzyme in active form
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catabolic pathways:
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metabolic pathways:
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release energy
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consume energy
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|
cellular respiration
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photosynthesis
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sunlight -> chemical bonds during photosynthesis
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exergonic:
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endergonic:
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positive / negative G free energy:
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negative
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positive
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released / absorbed
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released
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absorbed
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cellular respiration / photosynthesis
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cellular respiration
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photosynthesis
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uphill / downhill
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downhill
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uphill
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spontaneous
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spontaneous
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not spontaneous
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regulate internal body temperatures through metabolism
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balancing heat loss and gain
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five adaptations help animals thermoregulate:
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1) insulation
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2) circulating adaptations
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3) cooling by evaporative heat loss
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4) behavioral responses
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5) adjusting metabolic heat production
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location:
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cytoplasm
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reactants:
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~ glucose
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~ 2 ADP +2 Pi
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|
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~ 2 NAD+
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products:
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~ 2 pyruvate
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~ 2 ATP
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~ 2 NADH
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|
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~ 2 H2O
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|
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transfer of energy:
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NADH (electrons and Hydrogen) <- C6H12O6 -> ATP
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purpose:
|
~ convert glucose to pyruvate
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~ initial breakdown of sugar
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|
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~ generating ATP
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|
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~ shuttling e- and H+ to ETC
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molecular exchange of an electron
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oxidation: lose electrons
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reduction: gain electrons
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transformation of solar light energy trapped by chloroplasts into chemical bond energy stored in sugar and other organic molecules
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1) synthesizes energy rich molecules
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2) uses CO2 as carbon source
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3) directly or indirectly supplies energy
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CO2 + H2O + sunlight -> C6H12O6 + O2
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1) H2O splits
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~ H+: pump into thylakoid out of ATP synthase
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~ e-: 2 ETCs
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~ O2: released out of stomata
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2) light excites e- in Photosystem II
|
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3) e- to primary electron acceptor (PEA)
|
|
4) the e- travels down the ETC and replaces the e- from Photosystem I
|
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5) the e- travels down another ETC and combines with NAHP+
|
|
meanwhile...
|
|
~ energy from 1st ETC is used to pump H+ into the thylakoid space
|
|
~ a proton gradient forms and H+ leave through ATP synthase
|
|
~ H+ combines with e- and NADP+ to form NADPH
|
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~ ATP synthase generates ATP
|
|
reaction specific:
|
|
~ each enzyme works with a specific substrate chemical fit between active site and substrate
|
|
~ H bonds and ionic bonds
|
|
not consumed in reaction:
|
|
~ single enzyme molecule can catalyze thousands or more reactions per second
|
|
~ enzymes are unaffected by the reaction
|
|
affected by cellular conditions
|
|
~ ex: temperature, pH, salinity, etc.
|
|
as substrates increase, reaction rate increases and levels off
|
|
more substrate = more frequently collide with enzyme
|
|
the reaction levels off because...
|
|
~ all enzymes have active site engaged
|
|
~ enzyme is saturated
|
|
~ maximum rate of reaction
|
|
inhibitor competes with active site
|
|
substrate cannot bond
|
|
can overcome with substrate saturation
|
|
penicillin (competes with bacterial enzyme that builds cell wall)
|
|
directly blocks active site
|
|
the ability to do work
|
|
|
kinetic energy:
|
potential energy:
|
|
energy of motion
|
energy of position
|
|
heat
|
water behind a dam
|
|
light energy
|
chemical energy stored in cells
|
|
free energy: energy available to do work
|
|
free energy decreases when reactions proceed toward equilibrium
|
|
building complex molecules out of simple molecules
|
|
amino acids -> proteins
|
|
glucose -> glycogen
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do not regulate internal body temperature
|
|
rely on environmental heat sources
|
|
less respiration/food
|
|
catabolic
|
|
C6H12O6 + O2 -> CO2 + H2O + energy
|
|
steps:
|
|
1) gylcolysis
|
|
2) intermediate step
|
|
3) citric acid cycle
|
|
4) oxidative phosphorylation
|
|
location:
|
mitochondrial matrix
|
|
reactants:
|
2 pyruvate
|
|
products:
|
~ acetyl CoA
|
|
~ 2 NADH
|
|
|
~ 2 CO2
|
|
|
transfer of energy:
|
pyruvate (sugar) -> NADH (e- and H+)
|
|
purpose:
|
convert pyruvate into more reactive Acetyl CoA
|
|
location:
|
~ inner membrane of mitochondria (ETC)
|
|
~ inner membrane spare (chemiosmosis)
|
|
|
reactants:
|
~ NADH
|
|
~ FADH2
|
|
|
~ ADP+P
|
|
|
~ O2
|
|
|
products:
|
~ NAD+H
|
|
~ FAD+H
|
|
|
~ ATP
|
|
|
~ H2O
|
|
|
transfer of energy:
|
NADH/FADH2 -> proton gradient -> ATP synthase -> ATP
|
|
purpose:
|
use REDOX reactions to make a large amount of ATP (34)
|
|
autotrophic nutritional: nutritional made of synthesizing organic molecules from inorganic raw materials
|
|
photoautotrophs: uses light energy
|
|
chemoautotrophs: oxidation of inorganics for energy
|
|
site of photosynthesis
|
|
double membrane system
|
|
thylakoids: flattened photocenters
|
|
granum: stacks of thylakoids
|
|
stroma: fluid outside thylakoid
|
|
location: stomata
|
|
production of sugar
|
|
recognition of RUBP
|
|
reactants: CO2, NADPH, ATP
|
|
products: C6H12O6, NADP+, ADP+Pi, G3P
|
|
noncyclic photophosphorylation produces ATP and NADPH
|
|
cyclic photophosphorylation is ATP production
|
|
calvin cycle consumes more ATP than NADPH
|
|
"lock and key"
|
|
3-D structure of enzyme fits substrate
|
|
substrate binding cause enzyme to change shape leading to a tighter fit
|
|
"conformational change": slight change in shape
|
|
bring chemical groups in position to catalyze reactions
|
|
as enzymes increase, reaction rate increases
|
|
more enzymes = more frequently collide with substrates
|
|
optimum temperature:
|
|
|
~ as temp increases, reaction rate increases
|
~ greater number of molecular collisions
|
|
cold temperature:
|
|
|
~ molecules move slower
|
~ decrease collisions between enzymes and substrates
|
|
heat (beyond optimum)
|
|
|
~ increased energy level disrupts weak bond in 2' and 3' structure
|
~ denaturation: loses 3D shape
|
|
inhibitor binds to allosteric site (not active site) which changes the shape of the active site
|
|
ex: anti-cancer drugs, cyanide, poisoning, DDT
|
|
study of energy transformation
|
|
first law: energy of the universe is constant
|
|
second law: every process increases the entropy of the universe
|
|
entropy: "quantity of energy in universe is constant, but quality is not"
|
|
coupling endergonic/exergonic reactions
|
|
energy coupling: phosphorylated intermediates; regeneration of ADP to ATP
|
|
3 main types of work
|
|
1) mechanical work (motor protein)
|
|
2) transport work (Na/K pump)
|
|
3) chemical work
|
|
larger mammals have more body mass and require more chemical energy (higher BMR)
|
|
smaller animals require more kcal/gram, have greater rate of O2 delivery, higher breathing rate
|
|
increase activity -> increase metabolic rate -> more ATP
|
|
location:
|
mitochondrial matrix
|
|
reactants:
|
~ acetyl CoA
|
|
~ citric acid
|
|
|
~ ADP + Pi
|
|
|
~ NAD+ and FAD
|
|
|
products:
|
~ oxaloacetate
|
|
~ ATP
|
|
|
~ NADH and FADH2
|
|
|
~ CO2
|
|
|
transfer of energy:
|
NADH and FADH2 (e- and H+) <- citric acid -> ATP
|
|
purpose:
|
~ complete the oxidation of glucose
|
|
~ producing NADH/FADH2 (e- and H+)
|
|
|
~ ATP
|
|
substrate-level: ATP is synthesized by enzymes
|
|
oxidative: ATP is synthesized by an ETC and chemiosmosis
|
|
anaerobic process (no O2)
|
|
produces small amounts of ATP
|
|
regenerates NAD+/NADH
|
|
alcoholic fermentation
|
|
~ yeast/bacteria
|
|
~ produces CO2 and alcohol
|
|
lactic acid
|
|
~ human muscles
|
|
~ yogurt
|
|
~ produces lactic acid
|
|
heterotrophs: acquire organics to create energy from other creatures
|
|
~ consumers
|
|
~ decomposers
|
|
occurs in the thylakoid
|
|
splitting of water
|
|
generation of ATP and NADPH
|
|
reactants: H2O, NADP+, ADP+Pi
|
|
products: O2, NADPH, ATP
|
|
1) carbon fixation
|
|
~ ribulose biphosphate: RuBP
|
|
~ rubisco: RuBP carboxylase: most abundant protein
|
|
2) reduction
|
|
~ adding H+ and e- from NADPH to CO2 to make sugar
|
|
3) regeneration
|
|
~ G3P -> RuBP
|
|
photorespiration: fixing oxygen rather than CO2
|
|
|
C3 plants:
|
~ hot/dry days
|
|
~ stomata close (prevents H2O, inc CO2, dec O2)
|
|
|
C4 plants:
|
~ spatial separation of calvin cycle into bundle sheath cell
|
|
~ PEP carboxylase initially captures CO2
|
|
|
CAM pathways:
|
~ temporal separation
|
|
~ takes in CO2 at night
|
|
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