What is Cellular Respiration?
Cellular respiration is an aerobic process in which cells produce energy from food by gradually converting glucose molecules into ATP, carbon dioxide, & water molecules with the presence of oxygen
Where does it occur?
Cellular respiration occurs in the mitochondria of a cell
Cellular Respiration is a catabolic reaction in which glucose & oxygen molecules are broken down into carbon dioxide, water, & ATP molecules
Stage 1 - Glycolysis
A 6-carbon glucose molecule is split into 2 pyruvate molecules & 2 ATP molecules are formed
- 2 phosphate molecules are added to a 6-carbon molecule of glucose provided by energy of 2 ATP molecules
- The result is a 6-carbon sugar diphosphate & 2 ADP
- The 6-carbon diphosphate molecule is split into 2 3-carbon sugar molecules
- These 2 molecules are converted into 2 pyruvate molecules through a series of steps
- Electrons are transferred to the coenzyme NAD+
- 2 NADH & 2 ATP are formed
- (Aerobic) if oxygen is present, the pyruvate is oxedyzed to form more ATP
- (Anaerobic) if oxygen is not present, the pyruvate is converted into lactic acid
- occurs in all living organisms
Occurs in the cytoplasm of a cell
Stage 2 - Krebs Cycle (Citric Acid Cycle)
2 molecules of pyruvic acid from glycoysis are broken down in carbon dioxide
- 3 more NADH are produced
- 2 FADH2 are made
- 2 more ATP are made
- only occurs if oxygen is present
- cannot occur in organisms that are obligate anaerobes (killed by oxygen)
Occurs in the matrix of mitochondria
Stage 3 - Electron Transport Chain
Electrons released from NADH & FADH2 move along electron transport chains to make more ATP
Electron Transport Chain Process
- NADH & FADH2 are used
- high energy electrons from the Krebs Cycle are used to convert ADP into ATP
- oxygen is a reactant & water is a waste product
Occurs in the cristae of mitochondria
Why is Cellular Respiration Important?
Cellular respiration is important because it provides the energy for living organisms to perform all of the other necessary functions to maintain life. It is the process where organisms exchange oxygen for carbon dioxide. Without cellular respiration, the cells in an organism would die because they would be lacking the oxygen needed for food conversion, and they would have no means of getting rid of their waste products.
n.a. "Powering the Cell: Cellular Respiration." CK-12 Foundation. n.a. Web. 10 January 2016. http://www.ck12.org/book/CK-12-Biology/section/4.3/
n.a. "Cellular Respiration." CK-12 Foundation. 8 December 2014. Web. 10 January 2016. http://www.ck12.org/assessment/tools/geometry-tool/plix.html?
n.a. "Steps of Cellular Respiration." Khan Academy. n.a. Web. 10 January 2016. https://www.khanacademy.org/science/biology/cellular-respiration-and- fermentation/overview-of-cellular-respiration-steps/a/steps-of-cellular-respiration
Aryal, Sagar. "Krebs (Citric Acid) Cycle Steps by Steps Explanation." Online Microbiology Notes. 15 November 2015. Web. 10 January 2016.