Cellular Respiration
Process that releases ___________________ by breaking down food molecules in the presence of oxygen
6 O2 + C6H12O6 --> 6 CO2 + 6 H20+_____________
oxygen + glucose --> carbon dioxide + water + __________________
3 Stages of Cellular Respiration
1. __________________________
2. Krebs Cycle
3. Electron Transport Chain
Each stage captures some of the chemical energy available in food molecules and uses it to produce ATP
Energy Molecules of Cellular Respiration
In cellular respiration, several molecules are used as _______________ ______________. These molecules carry
energy from one step of cellular
FAD+ + H2 = FADH2
_______________________ – First step in releasing the energy of glucose.
A molecule of __________________________ is broken into two molecules of _____________________ (a 3-carbon
takes place in the ___________________________
does not require oxygen – ________________________
Requires: 1 Glucose molecule (C6H12O6), 2 ATP
Produces: 2 ATP, 2 NADH and 2 pyruvic acid
Second Stage: Fermentation or Krebs Cycle
Glycolysis can be followed by ___________________________ or the Krebs cycle depending if _________________ is
______________________________ will occur if no oxygen is present.
_____________________________ will occur if oxygen is present.
Without Oxygen – Fermentation
_____________________________ - without the presence of oxygen
Fermentation - releases energy from food molecules in the ______________________ of oxygen
two types: ______________________________ and Lactic Acid Fermentation
Occurs in the _________________________
Types of Fermentation
_______________________ - causes bread to rise, used to make beer and wine
_______________________ - produced in muscles during rapid exercise when body can’t supply enough O2
causes painful, burning sensation and muscle soreness
With Oxygen - Kreb’s Cycle
Aerobic - in the presence of _________________________
Kreb’s Cycle also called _____________________________________
________________________ - 2nd stage of cellular respiration, in which pyruvic acid is broken down into CO2 in a
series of energy-extracting reactions, creating energy molecules.
Occurs in the ______________________________
Kreb’s Cycle
Requires: 1 Pyruvic Acid
Produces: CO2, NADH, FADH2, ATP
Kreb’s Cycle
As a pyruvic acid molecule enters the __________________________, a carbon is removed, forming CO2.
Carbons continue to be rearranged, releasing more CO2, while allowing the energy carriers to be charged.
This cycle will happen twice for every molecule of _______________________ broken down in glycolysis.
Third Stage: Electron Transport Chain
The electron transport chain uses the high-energy electrons from the Krebs cycle to convert _____________ into
Occurs in the mitochondrial matrix.
Electron Transport Chain (ETC)
Requires: NADH, FADH2, ADP
Produces: H2O, NAD, FAD, ATP
Electron Transport Chain
1. The ________________________________ generates high-energy electrons that are passed to NADH and FADH2.
2. The high-energy electrons (H+) from NADH and FADH2 are used up and passed along the proteins in the __________.
3. _____________________ serves as the ________________ electron acceptor forming a water molecule.
4. As H+ ions move through the ETC, _________
______________________ spins adding ADP to P forming ________.
Cellular Respiration Totals
______ molecule of glucose produces:
2 ATP in _____________________________
34 ATP in Kreb’s Cycle and Electron Transport Chain
Types of Energy
Quick Energy - ________________ only contain enough ATP for a few seconds of intense activity. Then, muscle cells
produce their ATP by lactic acid fermentation.
__________________________________ - Cellular Respiration is the only way to generate a continuing supply of ATP
energy is released more slowly than fermentation, which is why athletes have to pace themselves
15 to 20 min. of activity from carbohydrate stored in the body
after 20 min., energy comes from break down of fats
Photosynthesis vs. Respiration
Photosynthesis and cellular respiration take place in opposite directions!
Photosynthesis: Use light energy to build a sugar.
carbon dioxide + water + light energy → sugars + oxygen
Respiration: Break down sugar to release energy.
oxygen + sugars → carbon dioxide + water + energy
Photosynthesis vs. Respiration
Use light energy to build a sugar.
Process that “deposits” or captures energy.
Removes carbon dioxide from the atmosphere.
Releases oxygen into the atmosphere.
Photosynthesis vs. Respiration
Break down sugar to release energy.
Process that “withdraws” or releases energy.
Removes oxygen from the atmosphere.
Releases carbon dioxide into the atmosphere.

Cellular Respiration Guided Notes