2.2 d Cellular Respiration: How do your cells get energy?

The Food We Eat Energy is stored in food but can’t be directly used by our cells Cellular respiration converts oxygen and glucose into ATP so we can use it!

Cellular Respiration Cellular respiration is simply the process that converts one type of chemical energy (the energy stored in sugar) into another type…ATP

Cellular Respiration (The opposite of photosynthesis!) Breaks down glucose into carbon dioxide and water. This releases ENERGY! Stored energy is converted into ATP. C6H12O6 + 6O2= 6CO2 + 6H2O (The opposite of photosynthesis!)

There are MANY STEPS! Glucose is broken down slowly so as much sugar as possible can be converted into ATP Some energy is lost to heat One molecule of glucose is broken down can be converted to a net total of 38 molecules of ATP The process is not 100% efficient (38 are made, a few may be lost)

3 Steps of Cellular Respiration 1-Glycolysis: the breakdown of glucose. 2-The Kreb Cycle (citric acid cycle): the formation of electron carriers. 3-The electron transport chain: use of oxygen to make ATP.

In Eukaryotic Cells The first phase takes place in the cytoplasm of the cell The other phases happen in the mitochondria. (Known as the “powerhouse” of the cell because all of the ATP is formed there)

Glycolysis Glucose is converted into Pyruvate and energy

What’s Next? Kreb Cycle! After glycolysis pyruvate can take several paths If there is oxygen available- pyruvate moves inside the mitochondrion to make more ATP Without oxygen- the fermentation process begin inside the Mitochondria The Krebs Cycle is possible because of the Mitochondria's unique shape

Electron Transport Chain In the final steps of cellular respiration, the electron transport chain converts NADH and FADH2 into ATP. Oxygen combines with hydrogens and becomes water. (That is why this process only occurs in the presence of oxygen) Aerobic Respiration!

Fermentation When there is not enough oxygen, the next step after glycolysis will be fermentation instead of the citric acid cycle

Anaerobic Respiration (Fermentation) NAD+ is recycled so that is can be reused in the glycolysis process. No additional ATP is produced during fermentation, so the organism only obtains the two net ATP molecules per glucose from glycolysis Example: Yeasts carry on alcoholic fermentation in the absence of oxygen, making ethyl alcohol (drinking alcohol) and carbon dioxide. Alcoholic fermentation is central to bread baking. The carbon dioxide bubbles allow the bread to rise, and the alcohol evaporates. In wine making, the sugars of grapes are fermented to produce the wine.

Lactic Acid Fermentation Where lactic acid is a waste product of this process. Our muscles undergo lactic acid fermentation during strenuous exercise, when oxygen cannot be delivered to the muscles quickly enough. (Makes you sore!) Bacteria that produce lactate are used to make cheese and yogurt