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# Cellular Respiration - PowerPoint PPT Presentation

Cellular Respiration. Chemical Energy and Food. A Calorie (with a capital C) is the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. Note: The calorie you see on a cereal box is actually a kilocalorie or 1,000 Calories. 1 Calorie = 4,184 joules.

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## PowerPoint Slideshow about ' Cellular Respiration' - lucretia-armando

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Presentation Transcript

### Cellular Respiration

• A Calorie (with a capital C) is the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius.

• Note: The calorie you see on a cereal box is actually a kilocalorie or 1,000 Calories.

• 1 Calorie = 4,184 joules

• Cellular Respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

• Cellular Respiration Equation:

• 6O2 + C6H12O6 6CO2 + 6H2O + Energy

• First part of cellular respiration: Glycolysis.

• Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid (a 3-carbon compound)

• 2 ATP molecules are needed go into glycolysis

• The cell uses those two ATP and makes 4 ATP molecules and 2 NADH molecules

• Therefore, a net gain of 2 ATP and 2 NADH

• When oxygen is not present, glycolysis is followed by fermentation.

• Fermentation releases energy from food molecules by producing ATP in the absence of oxygen

• Fermentation is anaerobic – does not require oxygen.

• Two main types:

• Lactic acid fermentation

• Alcoholic fermentation

• Yeast uses alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes

• This process makes bread rise and of course alcohol

• Lactic acid can be made from pyruvic acid in the absence of oxygen

• This occurs in your muscles during rapid exercise when you’re not getting enough oxygen to your cells

• Lactic acid build up is painful = pain in muscles while working out

• Unicellular organisms going through lactic acid fermentation are used to make cheese, yogurt, buttermilk, and sour cream.

• In the presence of oxygen (aerobic), after glycolysis, pyruvic acid goes to the Krebs Cycle (also called the Citric Acid Cycle).

• During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide and energy is extracted

• Step 1: Pyruvic acid enters mitochondria. One carbon is wasted as carbon dioxide. Two carbons become acetyl-CoA and forms citric acid.

• Step 2: The citric acid is broken down, more carbon dioxide is released, and electrons are transferred to electron carriers.

• This carbon dioxide that is released is what you breathe out.

• Electrons from the Krebs Cycle are passed from NADH and FADH2 to the electron transport chain (ETC).

• The ETC uses these electrons from the Krebs cycle to convert ADP into ATP.

• Step 1: Electrons passed through carrier proteins located on membrane of mitochondria (eukaryotes) or cell membrane (prokaryotes).

• Oxygen is the final electron acceptor and combines with H+ to form water.

• Step 2: Every time 2 electrons move down the chain, H + is moved across the membrane.

• These H + ions make the membrane positive

• Step 3: As the H + ions move across the membrane, ATP synthase attaches a phosphate group to ADP making ATP.

• 36 total ATP produced in presence of oxygen

• Exercise that is intense and ends quickly will utilize fermentation.

• Example: 200 m dash

• Body only has enough ATP for a few minutes of intense activity

• Exercise that is long-lasted and steady will use cellular respiration.

• Example: aerobic exercises like swimming, running, dancing.

• Cell respiration generates a continuous, steady supply