Chapter 9: Cellular Respiration

Nutrition Energy in most food originally comes from the sun 2 ways to get food Autotrophs(a.k.a 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

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

Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Glycolysis Cytoplasm Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria. Mitochondrion Copyright Pearson Prentice Hall

Aerobic Respiration Occurs in the mitochondria Yields 36 ATP molecules 3 steps of aerobic respiration

Glycolysis Makes only 2 ATP and 2 pyruvates (pyruvic acid)

Glycolysis Glucose is broken in to 2 pyruvates! Occurs in the cytoplasm Glycolysis only creates 2 ATP Advantages of Glycolysis?? The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen.

Krebs Cycle (a.k.a. Citric Acid Cycle) Breaks down pyruvates (which means it continues breaking down the glucose that entered glycolysis) Produces: citric acid, 2 ATP, CO2

Electron Transport Chain Produces 34 ATP Converts ADP to ATP using ATP synthase

Cellular Respiration Song Total ATP Production for Aerobic Respiration 1 glucose molecule  38 ATP 2 from glycolysis 36 from Krebs cycle and Electron Transport Chain Cellular Respiration Song

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

Lactic Acid Fermentation Performed by animals and bacteria In humans: Transferred from muscles (occurs in muscle cells) Produced during strenuous activity/exercise Results in muscle soreness In bacteria: Used to make the following foods: yogurt, buttermilk, cottage cheese, sour cream

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

Ch. 9 Bell Ringer: 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 ________ involved in making beer and wine 2. What is the net energy gain in glycolysis? a. 4 ATP b. 2 ATP c. 36 ATP d. 38 ATP

Photosynthesis vs. 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 O2 Equation for process 6CO2 + 6H2O + light  C6H12O6 + 6O2 C6H12O6 + 6O2  6CO2 + 6H2O + ATP Exchange of gases Takes in CO2 and gives off O2 Takes in O2 and gives off CO2