Cellular Respiration Chapter 9 Cellular Respiration Cellular Respiration

Cellular Respiration Chapter 9: Cellular Respiration

Cellular Respiration §Living cells require §Organisms use their main energy source as §Cellular respiration is the process of §Energy is released in the process of respiration when the cells of plants and animals

Respiration § The breakdown of organic molecules is § Aerobic respiration consumes § Anaerobic respiration is similar to aerobic respiration but § Fermentation is a

Cellular Respiration § Cellular respiration includes both but is often used to refer to § Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the :

Redox Reactions § The during chemical reactions § This released energy is used to § Chemical reactions that transfer electrons between reactants are called § In oxidation, a substance § In reduction, a substance § In cellular respiration, the , or is

NAD+ § In cellular respiration, glucose and other organic molecules are broken down in a series of steps § • As an electron acceptor, NAD+ functions as an • Each NADH (the reduced form of NAD+) • NADH passes the electrons to the

Electron Transport Chain § Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction • O 2 pulls electrons • The energy yielded is

Stages of Cellular Respiration 1) Glycolysis - Anaerobic 2) Citric Acid Cycle - Aerobic 3) Oxidative phosphorylation - Aerobic

Mitochondria 1) Glycolysis • 2) Citric Acid Cycle • 3) Oxidative Phosphorylation (ETC) •

Step 1: Glycolysis § “Splitting of sugar” § Breaks down glucose (C 6 H 12 O 6) into § § Occurs in the § NAD picks up H+ and electrons to form NADH 2

Glycolysis Summary Location: Reactants Products § § § • ** Simple Summary total

Bridge Reaction § In the presence of O 2, § Before the citric acid cycle can begin, § In the mitochondria matrix… 1) Pyruvic Acid loses a C to form 2) The lost carbon 3)Acetic acid binds with

Step 2: The Kreb’s Cycle (Citric Acid Cycle) § Takes place within the § There are , each catalyzed by a specific enzyme § The acetyl group of acetyl Co. A joins the cycle by combining with oxaloacetate § The next seven steps

Step 2: The Kreb’s Cycle (Citric Acid Cycle) § 2 molecules of CO 2 are § NAD+ and FAD (flavin adenine dinucleotide - another ion carrier) § The NADH and FADH 2 produced by the cycle relay electrons extracted from food § The cycle generates § Recall that two molecules of pyruvate are formed during glycolysis resulting in

Kreb’s Cycle Summary Location: Reactants Products § § § Kreb’s Summary Kreb's Summary 2

Step 3: Electron Transport Chain (ETC) § • § Takes place in the § A series of molecules that excited electrons pass along, § Most of the chain’s components are which exist in ,

Step 3: Electron Transport Chain (ETC) § Following glycolysis and the citric acid cycle, NADH and FADH 2 account for most of the energy extracted from food § These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via § The carriers alternate as they accept and donate electrons § Electrons § They are finally passed to O 2 , forming

NADH and FADH 2 § Dump the electrons and protons they’ve gathered throughout glycolysis and the citric acid cycle § Again, • O 2 + 2 e- + 2 H+ H 2 O § Electrons are passed through a number of proteins § The chain’s function is to break the large freeenergy drop from food to O 2 into smaller steps that release energy in manageable amounts §

Chemiosmosis § Electron transfer in the ETC causes proteins to § H+ then moves back across the membrane, passing through channels in § ATP synthase uses the exergonic flow of H+ to drive § This is an example of chemiosmosis, § ETC Summary

ETC

ETC Summary Location: Reactants § § Product § • • Simpler ETC Summary Best ETC Summary

Whole Respiration Process Song I Found. . .

Total Energy Total ATP from 1 molecule of glucose in Stage ATP + 4 Total Glycolysis (b/c 2 are used in the first step) CA Cycle ETC _________ TOTAL During cellular respiration, most energy flows in this sequence: Glucose -> NADH -> electron transport chain -> proton-motive force -> ATP

Fermentation § Most cellular respiration requires § Glycolysis can produce ATP , glycolysis couples with to produce ATP § Fermentation uses instead of an electron transport chain to generate ATP § 2 Types: • • §

Lactic Acid Fermentation § In lactic acid fermentation, § Lactic acid fermentation by some fungi and bacteria is used § Human muscle cells use lactic acid fermentation

Lactic Acid Fermentation § Example: Burning feeling in muscles during a workout • From oxygen debt • • Lactate

Alcohol Fermentation § In alcohol fermentation, pyruvate is • Bacteria and fungi (yeast) § Alcohol fermentation by yeast is used in

Fermentation § Obligate anaerobes carry out fermentation or anaerobic respiration and § Yeast and many bacteria are facultative anaerobes, meaning that Review

Role of Macromolecules § Catabolic pathways funnel electrons from many kinds of organic molecules into cellular respiration § Glycolysis accepts a wide range of § • Amino groups can feed § Fats are digested to • Fatty acids are broken down by beta oxidation and yield § An oxidized gram of produces more than twice as much ATP as an oxidized gram of

Regulation of Cell Respiration § is the most common mechanism for control • If ATP concentration begins to , respiration • When there is ATP, respiration of § Control of catabolism is based mainly on

Review Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Define cellular respiration and state its importance as a life process. Differentiate between aerobic respiration, and fermentation. State and explain the chemical equation for cellular respiration. Define oxidation and reduction and explain the idea of redox reactions. Explain the use of NAD+ as a coenzyme. Explain the electron transport chain (ETC). Name the 3 major stages of cell respiration, along with their locations. Explain glycolysis, stating the reactants, products, and major activities. Explain the bridge reaction, stating the reactants, products, and major activities. Explain the Kreb’s cycle, stating the reactants, products, and major activities. Explain glycolysis, stating the reactants, products, and major activities. Explain the ETC, stating the reactants, products, and major activities. Explain the role of oxygen in the ETC. Define chemiosmosis and explain its role in cellular respiration. Differentiate between lactic acid fermentation and alcohol fermentation. Differentiate between oblicate anaerobes and facultative anaerobes. Explain the role of macromolecules in cellular respiration. Explain how cell respiration is regulated.