Key Words
1. anaerobic process: does not require O2 to
occur
2. aerobic process: requires O2 to occur
3. glycolysis: biochemical pathway that breaks
down glucose into pyruvic acid
4. pyruvic acid: 3-carbon molecule made from
glucose during glycolysis
5. NADH: an energy-carrying molecule
6. fermentation: another pathway that converts
glucose into ATP
What is Cellular Respiration?
• how cells receive energy from nutrients
• breaks down organic molecules (ex: sugars)
into ATP
• occurs in mitochondria (therefore, this occurs
in both plants AND animals)
Equation for Cellular Respiration
C6H12O0 + 6 O2 ------> 6 CO2 + 6 H20
(glucose)
(oxygen)
REACTANTS
(starting materials)
(carbon dioxide)
(water)
PRODUCTS
(end result)
Stages of Cellular Respiration
Stage 1 – GLYCOLYSIS
– uses glucose made during photosynthesis
– breaks down glucose into 2 molecules of pyruvic
acid
– in the process, a small amount of ATP and NADH is
made
What comes next depends on one factor…
the presence of OXYGEN.
Stage 2
NO, there is not O2 present:
• Stage 2 =
FERMENTATION
• creates lactic acid or
ethyl alcohol
– these can be converted
to ATP
– inefficient process
(wastes energy)
YES, there is O2 present:
• Stage 2 = AEROBIC
RESPIRATION
• Has two stages:
1. Krebs Cycle
2. Electron Transport
Chain (ETC)
Krebs Cycle
• Picks up where glycolysis left off.
• Takes 2 molecules of pyruvic acid (made in
glycolysis), converts them into various
molecules over several cycles
– involves enzymes such as Co-enzyme A
– Pyruvic acid is converted into Acetyl CoA via
enzymes. When this occurs, CO2 is produced.
• End result: 2 molecules of ATP made in each
cycle
• One glucose molecule will fuel two Krebs Cycle
(therefore, 1 glucose -> 4 ATP)
Electron Transport Chain
• similar to photosynthesis
• occurs on the inner membrane of
mitochondria
• transfers electrons throughout several
molecules, building up energy
• when enough energy is built up (from NADH
and FADH2), ATP is created
– NADH and FADH2 created during the Krebs Cycle
– chemiosmosis = production of ATP via chemicals