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What is Cellular Respiration?

The process whereby cells convert
carbohydrates to energy in the form of ATP
(energy storage molecule)

All cells undergo respiration

Aerobic respiration is the most efficient
method, yielding the greatest amount of
ATP per glucose molecule

Anaerobic respiration is less efficient but
provides a method for getting energy (ATP)
in the absence of oxygen
Aerobic Cellular Respiration Equation
C6H12O6 + 6O2
(glucose)
(oxygen)

6CO2 + 6H2O + energy
(carbon dioxide) (water)
Does this equation look familiar?
It is the reverse of the photosynthesis equation.
Aerobic Cellular Respiration:
Respiration in the Presence of Oxygen
Two Main Parts
1st Part: Anaerobic Process
 Glycolysis
 in cytoplasm
2nd Part: Aerobic Processes
 Krebs Cycle
 Electron Transport Chain
 in mitochondrion
Aerobic Cellular Respiration
Three steps:
1. Glycolysis
2. Krebs Cycle
3. ETC (Electron Transport Chain)
Glycolysis
• glycolysis is an anaerobic
process, meaning it does
NOT require oxygen
• occurs in the cytoplasm
• glucose is broken down
into pyruvate
• yields 2 molecules of ATP
2 molecules
Krebs Cycle
6CO2
2 molecules
•
aerobic metabolic process,
meaning it REQUIRES oxygen
•
also known as the Citric Acid
Cycle
•
occurs in the mitochondrion
•
takes the product of glycolysis
and converts it to carbon dioxide
•
yields 2 molecules of ATP
Electron Transport Chain
34 molecules
•
aerobic metabolic process
•
occurs in the mitochondrion
•
releases the greatest amount of
ATP
•
yields about 34 molecules of
ATP
• photosynthesis & cellular respiration are cyclic processes
• the products of one are the reactants of the other
Chloroplast
carbon dioxide
+
water
glucose
+
oxygen
Mitochondria
Anaerobic Cellular Respiration:
Respiration in the Absence of Oxygen
•
= Glycolysis + Fermentation
•
allows cells to produce ATP WITHOUT OXYGEN
• no ETC is present (recall how many ATP molecules
are created by the electron transport chain = ___
34 ATP)
• method used by anaerobic bacteria
• method used by organisms which
ordinarily undergo aerobic
respiration when there is no
oxygen present
Glycolysis + Fermentation
•
In the absence of oxygen, the product of
glycolysis (pyruvate) enters into the fermentation
pathway
• Two pathways (pathway is dependent on the
organism)
1. Alcoholic fermentation
2. Lactic acid
Fermentation
Alcoholic Fermentation
•
yeast undergo alcoholic fermentation
• glucose is converted to ethanol & carbon dioxide
• yields 2 ATP molecules
• applications
 CO2 makes bread rise
 brewing beer
 winemaking
 ethanol fuel
Lactic Acid Fermentation
•
•
glucose is converted to lactate
some bacteria undergo lactic acid fermentation
 applications = yogurt, sauerkraut, kimchi
•
muscle cells can
continue to produce
ATP when oxygen
runs low but muscle
fatigue and pain may
result
 fast twitch muscles for
sprinting
 white meat in poultry
Summarize: 3-2-1
3 Steps of Aerobic Cellular
Respiration
2 Types of Fermentation
1 Main Goal of Cellular Respiration