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NOTES: Ch 9 - Cellular Respiration: Harvesting Chemical Energy - Part 1: The Overview
Overview: Life Is Work
● Living cells require
● Some animals, such as the giant panda, obtain energy by
; others feed on
organisms that eat plants
● Energy flows into an ecosystem as
and leaves as
● Photosynthesis generates oxygen and organic molecules, which are used in
● Cells use chemical energy stored in organic molecules to
,
9.1 - Catabolic Pathways and Production of ATP:
● The breakdown of organic molecules is
● Fermentation is a partial degradation of sugars that occurs
● Cellular respiration consumes oxygen and organic molecules and
Principles of Energy Harvest
● Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with
the sugar glucose:
Org.
cmpds.
+

oxygen
carbon
dioxide
+
water
+
energy
Chemical equation:
Recall: the ATP cycle (sketch):
Redox Reactions: Oxidation and Reduction
● The transfer of electrons during chemical reactions
● This released energy is ultimately used to synthesize ATP
REDOX REACTIONS: involve
OXIDATION:
(“
“)
REDUCTION:
(“
“)
Example of REDOX: (label)
Na + Cl  Na+ + Cl● The electron donor is called the
● The electron receptor is called the
Oxidation of Organic Fuel Molecules During Cellular Respiration:
● During cellular respiration, the fuel (such as glucose) is oxidized and oxygen is reduced:
Respiration: (copy and label chemical equation):
*the transfer of electrons from 1 element to another, more electronegative element (e.g. from H to O) releases
stored potential energy - - this chemical energy can be put to work!
● Glucose & other fuels are
, in a series of steps
● at key steps, H atoms are stripped from glucose and passed to a coenzyme:
-(this is performed by enzymes:
)
(copy sample equation):
Stepwise Energy Harvest via NAD+ and the Electron Transport Chain
● As an electron acceptor, NAD+ functions as an oxidizing agent during cellular respiration
● Each NADH (the reduced form of NAD+) represents
that is tapped to synthesize ATP
● Respiration uses an ELECTRON TRANSPORT CHAIN to
(instead of one explosive reaction)
● NADH passes the electrons to the
● Oxygen pulls electrons down the chain in an energy-yielding tumble
● The energy yielded is
ELECTRON TRANSPORT CHAIN:
● consists of molecules, mostly proteins, built into the
● NADH
● oxygen captures electrons at the “bottom” of the chain and combines with H +,
SUMMARY OF ENERGY FLOW IN THE CELL:
**
The Stages of Cellular Respiration: A Preview
● Cellular respiration has three stages:
1) Glycolysis (
into two molecules of pyruvate)
2) The Citric Acid Cycle, a.k.a. Krebs Cycle (
)
3) E.T.C. & Oxidative phosphorylation (accounts for most of the ATP synthesis)
ATP Synthesis:
● The process that generates most of the ATP is called
because it is
powered by redox reactions
● Oxidative phosphorylation accounts for almost
● A small amount of ATP is formed in glycolysis and the citric acid cycle by
generated by cellular respiration