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CELLULAR RESPIRATION
CHAPTER 9
CELLULAR RESPIRATION
• Complex process where cells break down glucose to make ATP chemical energy
• Three main steps of aerobic respiration
1. Glycolysis: convert glucose (6-carbon) to pyruvic acid (3-carbon)
• 2. Krebs Cycle: Uses oxygen in the mitochondria to turn Acetyl CoA into energy
• 3. Electron Transport Chain: Series of chemical reactions that convert energy into ATP
in the mitochondria cristae; requires oxygen
• Makes 38 ATP
CELLULAR RESPIRATION
• The chemical energy stored in glucose makes much more ATP in aerobic respiration
than in respiration without oxygen (glycolysis and fermentation).
• Each molecule of glucose can make 36-38 molecules of ATP in aerobic respiration but
only 2 ATP molecules in respiration without oxygen (through glycolysis and
fermentation).
CELLULAR RESPIRATION OVERALL PROCESS
Uses:
Makes:
Cell types:
STEP ONE: GLYCOLYSIS
(*CELLULAR RESPIRATION)
• In glycolysis, the 6-carbon sugar,
glucose , is broken down into two
molecules of a 3-carbon molecule
called pyruvate. This change is
accompanied by a net gain of 2 ATP
molecules and 2 NADH molecules.
• *Occurs in the cytoplasm.
STEP 2: KREBS CYCLE (*CELLULAR RESPIRATION)
The Krebs cycle occurs in the mitochondria
and makes chemical energy (ATP, NADH,
and FADH2) by using pyruvate , the end
product of glycolysis.
Pyruvate is converted into acetyl-CoA. When
acetyl-CoA is changed into carbon dioxide in
the Krebs cycle, chemical energy is released
and captured in the form of NADH, FADH2,
and ATP.
STEP 3: ELECTRON TRANSPORT CHAIN (*CELLULAR RESPIRATION)
*Generates most of the ATP energy in
cellular respiration
*The chemical reactions occur one after
the other, like a domino chain
*The final step of cellular respiration
WHEN OXYGEN IS NOT PRESENT…
• Aerobic respiration cannot occur/ things stop at glycolysis
• Fermentation occurs instead
• Process:
• 1. Glycolysis
• 2. Fermentation Pathway
• A. Lactic acid fermentation
• B. Alcoholic fermentation
• Makes 2 ATP
FERMENTATION
All cells are able to synthesize ATP via the
process of glycolysis. In many cells, if
oxygen is not present, pyruvate is
metabolized in a process called
fermentation.
Fermentation complements glycolysis and
makes it possible for ATP to be made in the
absence of oxygen. By oxidizing the NADH
produced in glycolysis, fermentation
regenerates NAD+, which can take part in
glycolysis once again to produce more ATP.
CELLULAR RESPIRATION (AKA AEROBIC RESPIRATION)
• Uses oxygen and glucose to produce
ATP energy, plus water and CO2
• Other uses: may follow other
pathways to generate other
compounds needed (macromolecules
and biomolecules like amino acids not
found in foods)
WRAP-UP: CREATE A VENN DIAGRAM TO COMPARE
PHOTOSYNTHESIS AND CELLULAR RESPIRATION