Chapter 9: Cellular Respiration

Nutrition Energy in most food originally comes from the sun 2 ways to get food –Autotrophs or Producers Make their own food Uses photosynthesis or chemosynthesis Examples: plants, algae, some bacteria –Heterotrophs or Consumers Cannot make their own food Take in food by eating Examples: animals, protists, fungi, most bacteria

Cell Respiration Occurs in ALL living organisms Process in which mitochondria break down food molecules (sugars) to produce ATP 3 stages occur in cellular respiration: glycolysis, Krebs cycle, and electron transport chain

Glycolysis Takes place in the cytoplasm of a cell Breaks down glucose to make 2 molecules of pyruvic acid and NADH Needs 2 ATP molecules to start glycolysis Produces 4 ATP molecules 4-2=2 ATP gained (releases only a small amount of energy) This is an anaerobic process: does not require Oxygen

Glycolysis Aerobic Respiration Fermentation If Oxygen is present If Oxygen is not present

Anaerobic Respiration Fermentation  occurs in the absence of oxygen (2 kinds) Alcoholic Fermentation  yeasts –Produces carbon dioxide gas and ethyl alcohol –Ex: wine, bear, breads

Lactic Acid Fermentation Transferred from muscles (occurs in muscle cells) Produced during strenuous activity/exercise –Results in muscle soreness Examples in food: yogurt, buttermilk, cottage cheese, sour cream

No additional ATP molecules are produced Only 2 ATP produced from glycolysis and anaerobic respiration

Aerobic Respiration Occurs in the mitochondria Yields 36 ATP molecules 3 steps of aerobic respiration –Pyruvic Acid conversion (glycolysis)

Krebs Cycle (Citric Acid Cycle) Breaks down glucose Acetyl CoA  citric acid (2 ATP produced) + CO 2

Electron Transport Chain Produces 34 ATP Converts ADP to ATP

1 glucose molecule  38 ATP –2 from glycolysis –36 from Krebs cycle and Electron Transport Chain

Photosynthesis vs. Cellular Respiration Photosynthesis Cellular Respiration What does it do? Makes glucose Breaks down glucose Why do it?To store energy To release energy Who does it involve? “green organisms”, some bacteria, algae, plants ALL organisms When does it occur? The day into night All the time Where does it occur? Chloroplasts Starts in the cytoplasm Ends in the mitochondria in the presence of O 2 Equation for process 6CO 2 + 6H 2 O + light  C 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP Exchange of gases Takes in CO 2 and gives off O 2 Takes in O 2 and gives off CO 2

Review: 1.Identify which phrase describes the following: lactic acid fermentation alcoholic fermentation ________ important in baking bread ________ builds up in muscles after a few seconds of intense activity ________ the reasons why runners breathe heavily after a race ________ involves in making beer and wine 2. What is the net energy gain in glycolysis? a. 4 ATPb. 2 ATP c. 36 ATPd. 38 ATP

Bell Ringer: 1.Glycolysis produces a net gain of _____ ATP molecules for each reaction. 2.Identify if the phrase below is describing photosynthesis or cellular respiration: ________ reactants are CO2 and H2O ________ occurs only in plants, algae, and some microorganisms ________ 6O2 +C6H12O6  6CO2 + 6H2O + Energy ________ uses oxygen to release energy from food 3. What is another name for the Krebs cycle? a.Glycolysisb. Alcoholic fermentation c. Citric acid cycled. Respiration