Chapter 7 Flashcards
cellular respiration
aerobic
with oxygen
more efficient more atp
cellular respiration
anaerobic
without oxygen
partial degradation
Exergonic
Change in G = negative
spontaneous
G reactants > G products
release energy
Endergonic
Change in G = positive
G reactants < G products
Require energy
Reduction
Reactant gains electron or H
Product lost oxygen
Reactant becomes “reduced”
Reactant acts like “oxidizing agent”
Oxidizes second reactant (donates electron or H)
Oxidation
Reactant looses e or H
Product gains oxygen
Reactant becomes “oxidized”
Reactant acts like “reducing agent”
Reduces first reactant (accepts electron or H)
OILRIG
Oxidation is loss
Reduction is gain
Combustion reaction
release tremendous energy
heat energy useful
partial oxidation/reduction
Partially oxidized/reduced
partial gain or lost e
covalent bonds
carbon in CH4
Oxygen in O2
redox
oxidation-reduction reactions
movement of electrons and H
most energy conserved with movement
electron transfer -> energy release
electrons may be “carried”
Uncontrolled
rocket fuel
change in G = very neg (exergonic)
explosive energy release
impossible to capture
Stepwise energy release
Cellular respiration
change in G = negative (exergonic)
release over multiple steps
each step = redox rxn
steps = stronger affinity to e
able to capture energy
stronger affinity = stronger oxidizer
Nicotinamide adenine dinucleotide (NAD) or NADH
electron carrier molecule
NAD+ + e= NADH
e form glucose
dehydrogenase (enzyme) moves H/e
carriers 2 e and 2 H (uses one H)
Flavin adenine nucleotide (FAD)
Flavin adenine nucleotide
(FAD)
electron carrier
electron transport chain
proteins in membrane
bottom step oxidizes top step
O2 terminal e acceptor
O2 highest e affinity
O2 “pulls” electron down chain
similar to gravity down hill
Cellular respiration equation
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (heat loss + usable energy)
Stages of cellular respiration
- Glycolysis
- Pyruvate Oxidation
- Citric acid cycle
- oxidative phosphorylation
Glycolysis Overview
Glucose broken down to pyruvate, producing ATP and reduced electron carriers
Pyruvate Oxidation Overview
Pyruvate is converted to acetyl-coA producing reduced electron carriers, and CO2
Citric acid cycle Overview
acetyl-coa enters the cycle, producing ATP, reduced electron carriers, and CO2
Oxidative Phosphorylation Overview
Reduced electron carriers donate e to electron transport chain, leads to ATP synthesis
Energy in ATP
7.3 kcal/mol
Kinase
enzyme, phosphorylation
Dehydrogenase
reduction
Glycolysis
“sugar splitting”
in cytosol
no o2 needed
e investment (-2ATP)
e payoff (+4ATP)
net = 2
only 1/4 of glucose energy released
Major products of Glycolysis
+2 pyruvate
+2 NADH
+2 ATP (net)
+2 H+ 2 H2O
Pyruvate Oxidation
When O2 present
links glycolysis to citric acid cycle
pyruvate -> pyruvate dehydrogenase
catalyzes 3 reactions
1. carboxy fully oxidized -> (2 total CO2)
2. Electron transfer -> reduction of NAD+ to NADH
3. Coenzyme A transferred -> acetyl coa (w/ sulfur)
Acetyl CoA (high potential energy) starting substrate for Krebs
Where does glycolysis occur
cytosol (pro and euk)
Where does pyruvate oxidation occur
Pro -> cytosol
Euk -> cytosol to mito matrix
Citric acid cycle
“krebs cycle”
Acetyl CoA initial substrate
regeneration of oxaloacetate
most energy held in carriers
transferred to ETC
extracted -> oxidative phospho
Where does the citric acid cycle occur
Pro -> cytosol
Euk -> mito-matrix
Products of Citric acid cycle
+6 NADH
+ 2 FADH2
+2 GTP or ATP
+4 CO2
+ 2H2O but -4H2O
(net 0 because 2 in glyco)
Oxidative Phosphorilation
most ATP produced at this step
part 1. electron transport chain
part 2. Chemiosmosis
Electron Transport Chain
Most energy held in carriers created in other steps
Protein complexes in membrane
each step down = higher affinity
higher affinity = better oxidizer
O2 = terminal electron acceptor
NADH “better” (higher E state) than FADH2
release energy in usable quantities
no ATP directly, releases E to eventually create ATP
Where does the ETC occur
Pro -> PM cytosol
Euk -> mito-membrane matrix
Electron transport chain
+ 10 NAD+
+2 FAD
Both ready to pick up more H
+ 6H2O
Chemiosmosis
Energy coupling mechanism (ender and exer)
ETC is exergonic
energy from electron transfer
pumps H ions into intermembrane space
creates gradient with potential energy
proton membrane force (PMF) = potential energy
ATP synthesis is endergonic
Inorganic P + ADP -> ATP
1. H diffuses through stator
2. H+ binds to rotor
causes spinning internal rod, spinning activates catalytic sites in knob
3. catalyze phosphorylation of ADP -> ATP
like water spins a waterwheel
Oxidative phosphorylation products
+ 6 H2O
+ (26-28) ATP
+ 10 NAD+
+ 2 FAD
Where does oxidative phosphorylation take place
Pro - Cytoplasm
Euk - mito-intermembrane space
Why is ATP production inexact
ATP yield depends on carrier
PMF drives other processes
Cellular respiration in 34% efficient
Anaerobic cellular respiration
without O2
still uses ETC
different final e acceptor
diff oxidizer (SO4 2-) (sulfate)( not humans -> bacteria)
aerobic bacteria -> saltmarsh
Fermentation
no ETC
rely solely on glycolysis
2 net ATP
always regardless of O2
limited by NAD + availability because no ETC
Alcohol fermentation
Bacteria and Fungi
ethanol
Lactic acid fermentation
strenuous activity
no CO2 produced
no O2
least ATP to most ATP production
- (most) Aerobic
- Anaerobic
- (least) fermentation
Connected pathways
can derive energy from proteins, starch/disaccharides, glycerol/fatty acids (gram to gram)
intermediate shunted to anabolic pathways
do not directly consume glucose
Control of metabolism
feedback inhibition
phosphofructokinase (enzyme for glycolysis)
main control mechanism with many sites
stimulatory: more AMP low [citrate], stimulate production
inhibitory: more ATP, high [citrate], inhibit production
highly efficient and responsive
occurs locally at cell level
dehydrogenase
catalyzes reduction
kinase
phosphorylation
ADP -> ATP
ATP from NADH
2.5
ATP from FADH2
1.5
How much uptake can uptake of pyruvate into mitochondria use
2
phosphofruktokinase
enzyme for glycolysis
control mechanism for ATP production
high AMP -> activates
low ATP or citrate -> stops
energy from cell respiration
30-32 ATP
686 kcal/mol
substrate level phosphorilation
everything but oxidative phosphorylation
formula for alcohol fermentation
C6H12O6 (glucose) ->
2C2H5OH (ethanol)
+ 2CO2
+ 2ATP
formula for lactic acid fermentation
C6H12O6 (glucose) ->
2CO2
+ 2 ATP
+ C3H6O3 (lactic acid)
