cellular respiration: harvesting chemical energy
DESCRIPTION
Cellular Respiration: Harvesting Chemical Energy . Cellular Respiration. Glycolysis The Kreb Cycle (Citric Cycle) Electron Transport Chain (Chemiosmosis and oxidative phosphorylation). Cellular Respiration . Cells harvest chemical energy stored in molecules and use this to generate ATP. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/1.jpg)
Cellular Respiration: Harvesting Chemical Energy
![Page 2: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/2.jpg)
Cellular Respiration
1. Glycolysis2. The Kreb Cycle (Citric Cycle)3. Electron Transport Chain
(Chemiosmosis and oxidative phosphorylation)
![Page 3: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/3.jpg)
Cellular Respiration Cells harvest chemical energy stored in
molecules and use this to generate ATP.
Organic compounds store energy in their arrangements of atoms.
![Page 4: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/4.jpg)
Catabolic (releases energy) Exergonic (- G, products store less
energy than reactants) Occurs mostly in the mitochondria (but
first step is in cytosol) C6H12O6 + 6O2 6CO2 + 6H2O + energy
(ATP and heat)
![Page 5: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/5.jpg)
General Points Phosphorylation: the transfer of a
phosphate moleculethe production of ATP (adenosine triphosphate)ADP + P i ATP
Oxygen is very electronegative (i.e. it wants electrons ...think of its Bohr
model)
![Page 6: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/6.jpg)
Redox 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
![Page 7: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/7.jpg)
Sodium and Chlorine (think of the Bohr Models) Which atom is the electron donor?
Acceptor/ Which atom is the reducing agent?
Oxidizing agent?
![Page 8: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/8.jpg)
![Page 9: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/9.jpg)
Overview 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 molecule
First they are transferred to a coenzyme NAD+
• NAD + wants to gain electrons (to be neutral)
![Page 10: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/10.jpg)
![Page 11: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/11.jpg)
NAD + 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?
![Page 12: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/12.jpg)
So if we removed two hydrogen atoms, that means we remove two electrons and two protons
C6H12O6
![Page 13: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/13.jpg)
Enzyme 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.
![Page 14: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/14.jpg)
![Page 15: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/15.jpg)
Little 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
![Page 16: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/16.jpg)
![Page 17: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/17.jpg)
Pathway of Electrons Electrons (from glucose in the form
of hydrogen atoms) move to NAD+ NADH oxygen (final electron acceptor)
![Page 18: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/18.jpg)
Glycolysis(“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 a net result of 2 molecules of usable ATP
Produces 2 molecules of NADH Can occur without the presence of oxygen
![Page 20: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/20.jpg)
Oxidizing 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: dehydrogenase
Hydrogen atoms are stripped from glucose and passed to a coenzyme: NAD + (oxidizing agent)
![Page 21: Cellular Respiration: Harvesting Chemical Energy](https://reader035.vdocuments.net/reader035/viewer/2022070501/56816937550346895de09ab6/html5/thumbnails/21.jpg)
The dehydrogenase removes two hydrogen atoms from the glucose (2 p+ and 2e-)
NAD+ traps 2e- and 1p+ from glucose break down = NADH
NADH-stored energy ready to make ATP when e- complete their journey to oxygen.