Cellular Respiration Unit 8

Cellular Respiration Cellular respiration: process by which cells (animal and plant) break down food molecules into ATP (energy) http://www.sumanasinc.com/webcontent/animations/content/ cellularrespiration.html

Cellular Respiration A series of metabolic processes that take place within a cell in which biochemical energy is harvested from organic substance (e.g. glucose) and stored as energy carriers (ATP) for use in energy- requiring activities of the cell.

What does that mean? We cannot use food directly as energy, we have to break the bonds within nutrients to get energy in the form of ATP. To make ATP we take glucose from the food we eat plus oxygen we breathe in and make energy and water, plus the waste product carbon dioxide.

Where does respiration happen? Begins in the cytoplasm Remember the powerhouse of the cell? mitochondria

Electron Transport Chain Animal Cell Citric Acid Cycle (Outer membrane of mitochondria) Electron Transport Chain (Inner membrane of mitochondria) 2 3 1 Glycolysis (Cytoplasm)

Respiration Formula C6H12O6 + 6O2  6CO2 + 6H2O + (ATP) Glucose is the fuel for the cell, but it is not in a form that we can use, it has to be converted into ATP, the ultimate cellular energy source. Remember, the cycle of matter!

Steps for Cellular Respiration 1. Glycolysis: process in which one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid. *anaerobic 2 ATP produced 2. Krebs Cycle: process in which pyruvic acid is broken down into carbon dioxide. *aerobic 3. Electron Transport Chain (ETC): uses the high energy electrons from the Krebs cycle to convert ADP into ATP . *aerobic 32 ATP produced

Types of cellular respiration Aerobic Anaerobic Occurs in the presence of oxygen Maximizes ATP output Each cycle through aerobic respiration makes 36 ATP molecules. Happens without oxygen Minimal ATP output (since it occurs without additional oxygen) Each cycle through anaerobic respiration makes 2 ATP molecules.

Anaerobic Respiration Lactic Acid Fermentation Alcoholic Fermentation Occurs in animals This is what happens to your muscles after you work out too long, you build up lactic acid. Need ATP, muscles can’t get O2 fast enough Pyruvate  lactic acid Occurs in plants and fungi This is how bread and beer is made. Ex. Yeast, CO2 released causes bread to rise. Pyruvate  ethyl alcohol + carbon dioxide

Does ALL of your glucose get used? ALL of your glucose does not get used. 36 ATP (energy molecules) is best case scenario Some of your glucose is broken down but lost as heat NOT transferred into ATP. THINK! Does your car use every ounce of gasoline you put in it? No most of it is lost as exhaust and heat energy.

Photosynthesis and Respiration are the opposite of each other: Plants use sunlight to make glucose take in carbon dioxide give off oxygen *carbon dioxide + water + sunlight  glucose + oxygen Respiration Animals and plants eat plants to get glucose take in oxygen give off carbon dioxide *glucose + oxygen  carbon dioxide + water + ATP

Photosynthesis and Respiration are the opposite of each other:

ATP… now what?

Cellular Respiration ATP Totals for aerobic respiration: Glycolysis – 2 ATP Citric Acid Cycle – 2 ATP + Electron Transport Chain – 32 ATP 1 Glucose = 36 ATP in all for aerobic respiration