Cellular Respiration Cells harvest chemical energy stored in molecules and use this to generate ATP Organic compounds store energy in their arrangements of atoms Catabolic releases energy Exergonic ID: 778251
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Slide1
Cellular Respiration: Harvesting Chemical Energy
Slide2Cellular Respiration
Cells harvest chemical energy stored in molecules and use this to generate ATP.
Organic compounds store energy in their arrangements of atoms.
Slide3Catabolic (releases energy)
Exergonic
(- G, products store less energy than reactants)
Occurs mostly in the mitochondria (but first step is in cytosol)C6H12O6 + 6O2
6CO
2 + 6H2O + energy (ATP and heat)
Slide4Redox Reaction Recap
Involves the transfer of electrons
LEO (loss of electrons)
oxidation (less -)GER (gain of electrons) reduction (more -)
Electron donor (reducing agent
) the atom that becomes less negative (positive)
Electron acceptor (oxidizing agent) the atom that becomes more negative
Slide5Sodium and Chlorine (think of the Bohr Models)
Which atom is the electron donor? Acceptor/
Which atom is the reducing agent? Oxidizing agent?
Slide6Slide7Three Processes in Cell
Resp
Glycolysis
The Kreb Cycle (Citric Cycle)
Electron Transport Chain (Chemiosmosis and oxidative phosphorylation)
Slide8Glycolysis(
“splitting of sugar”)
Glucose is split into two, three carbon sugars called
pyruvate
Catabolic pathway (breakdown)
Occurs in the
cytosol
Two major phases
Energy investment (puts in 2 ATP)
Energy payoff (creates 4 ATP)
Produces 2
molecules of usable
ATP (4 total but we have to put in 2 ATP, so only 2 left for cell use)
Produces 2 molecules of NADH
Can
occur without the presence of oxygen
Slide9Slide10glycolysis
Slide11Oxidizing Glucose
The oxidation of glucose allows energy to be taken out of storage and make energy available to make ATP.
Glucose is broken down
gradually in a series of steps catalyzed by an enzyme: dehydrogenaseHydrogen atoms are stripped from glucose and passed to a coenzyme: NAD + (oxidizing agent)
Slide12The dehydrogenase removes two hydrogen atoms from the glucose (2 p+ and 2e-)
NAD+ traps 2e- and 1p+ from glucose break down = NADH
NADH stores
energy ready and will pass on electrons to make ATP when e- complete their journey to oxygen.
Slide13Overview of Cellular Respiration
Step by step process that releases energy along the way (does not release all energy at once)
Hydrogen atoms are stripped away from glucose
Hydrogen atoms ultimate destination is the oxygen moleculeFirst they are transferred to a coenzyme NAD+
NAD + wants to gain electrons
(to be neutral)
Slide14Slide15NAD + traps electrons from glucose using dehydrogenase (enzyme) which removes a pair of hydrogen atoms from glucose
STOP and THINK of a Bohr model for hydrogen: How many electrons? How many protons?
Slide16So if we removed two hydrogen atoms, that means we remove two electrons and two protons
C
6
H12O6
Slide17Enzyme gives two electrons and one proton to its coenzyme NAD +
forming NADH
The other proton (left over) is released into the surrounding environment
Is NAD+ an electron acceptor or donor?Is NAD+ an oxidizing agent or a reducing agent?**NAD+ is the most versatile electron acceptor in cell resp.
Slide18Slide19Little potential energy is lost when e- are transferred from glucose (food) to NAD+
NADH molecules represent stored energy that can be used to make ATP when e- complete their “fall” to oxygen
An electron transport chain is used to break the fall of electrons to oxygen
Produces several energy releasing steps NOT one big explosion of energy
Slide20Slide21Pathway of Electrons
Electrons (from glucose in the form of hydrogen atoms) move to
NAD+ NADH oxygen (final electron acceptor)
Slide22Cell Respiration Terms
Phosphorylation
:
the transfer of a phosphate molecule
the production of ATP
(adenosine
triphosphate)ADP + P i ATP
Oxygen is very
electronegative
(i.e. it wants electrons ...think of its Bohr
model)