Unit 2: The Cell
Animations
Study Guide
Chapter 9
Cellular Respiration
Review
Notes
Living
organisms
require
energy
to perform cellular work.
Energy
flows into most ecosystems as
sunlight
and
leaves
as
heat
.
Electron
transfer drives the transformation of energy and occurs through
redox
reactions.
Molecules such as NAD
+
and FAD act as electron
carriers
in redox
reactions.
In cellular respiration,
redox
reactions occur in a series of steps called the
electron
transport
chain
to form
ATP
.
Cellular
respiration
comprises three metabolic stages:
glycolysis
,
citric
acid cycle, and
oxidative
phosphorylation.
Glycolysis
occurs in the
cytosol
to produce two molecules of
ATP
from the metabolism of one
glucose
molecule.
The
pyruvate
is
converted
to
acetyl
CoA, which enters the
citric
acid
cycle.
During
oxidative
phosphorylation, NADH and FADH
2
donate
electrons
to the
ETC
to produce even more
ATP.
Review: Cellular Respiration
In
anaerobic
conditions, glycolysis may be
followed
by
fermentation
.
Other organic molecules such as
proteins
and
fats
can also enter cellular respiration via different
catabolic
pathways.