Ch. 7.4: Cellular Respiration

Ch. 7.4: Cellular Respiration Vocabulary Aerobic Electron transport chain Objectives: • Relate breathing and cellular respiration. • Summarize the cellular respiration equation. • Tell how “falling” electrons are a source of energy. • Explain the role of electron transport chains.

Ch. 7.4: Breathing & Respiration Cellular respiration converts the energy stored in food to energy stored in ATP. Physical processes of moving O2 & CO2 Chemical rxn involving the oxidation of glucose to H2O& CO2 Gases exchanged b/w blood & outside air via lungs. Gases exchanged b/w cells & surroundings (blood or lymph)

Ch. 7.4: Cellular Respiration Equation Respiration occurs in a SERIES of reactions (not 1 rxn). Goal: Generate ATP for cellular work.

7.4: Where does energy for ATP come from? Moving to an outer energy level is like climbing uphill … it costs energy. Moving to a lower energy level is like moving downhill. Falling Electrons = Energy Source for ATP “Falling Electrons” release energy; Excited --> ground state Why?: Negative electrons are attracted to positive nucleus. Moving farther fr. nucleus requires energy; falling to nucleus releases energy.

7.4: Reacting with Oxygen; Oxidation Oxygen is an excellent “electron-grabber”; electrons are pulled to O (electro-negative). (O is much better than N or H @ attracting electrons) In respiration, C-H bonds of glucose are re-arranged into C-O and H-O bonds of carbon dioxide and water. These bonds store less energy. The energy difference is stored in ATP. Respiration Oxidation + ATP ENERGY If glucose is BURNED in a combustion rxn; energy is released as heat and light all at once.

7.4: Electron Transport Chains (E.T.C.) • Energy from glucose is released in small steps. • Electrons from glucose are passed from one molecule to another in an E.T.C. • Each transfer releases energy to make ATP. Electrons are “falling downhill”. • O2 is ultimate electron-grabber @ end of ETC. O2 grabs electrons and combines w/ H+ions to form H2O.

7.5: Making ATP Vocab: Metabolism Krebs Cycle Glycolysis ATP synthase Objectives: Describe the structure of the mitochondrion. Summarize the 3 stages of cellular respiration and identify where ATP is made.

7.5: Mitochondia Found in almost all eukaryotic cells. 2 membranes (inner & outer) Inner membrane - highly folded w/ enzymes (ATP synthase) built in. Thick fluid in matrix. Structure & Function go together: Folds of inner membrane increases surface area for enzymes and sites for reactions … MORE ATP gets made (more surface area = more ATP synthase)!

7.5: Steps of Cellular Respiration Metabolism: all of a cell’s combined chemical reactions. Respiration is a series of rxns … a metabolic pathway.

Step 1: Glycolysis • Break down glucose molecule into (2) 3 carbon-molecules called PYRUVATES. • Outside mitochondria, in cytoplasm (cystol) • Requires 2 ATPs to break glucose; Electrons & H+ ions transfer to NAD --> NADH and make 4 ATP • Summary: Glucose breaks down into 2 Pyruvates (3 C) and 2 ATPs!

7.5: Step 2: Krebs Cycle • Pyruvic acid (3C) --> Acetyl CoA (2C) --> CO2; Energy Released and stored in ATP, NADH, and FADH2 (Electron acceptors) • Where: Enzymes in fluid matrix inside inner membrane. • Summary: 2 Pyruvate (3C) break down to CO2 & 2ATP, NADH, FADH2

7.5: Step 3: Electron Transport Chain and ATP Synthase Action • Electrons (fr. Glucose) carried by NADH move thru. E.T.C. (getting pulled by stronger electron-attractor molecules) • Oxygen grabs electrons @ end; combines w/ H+ to make H2O. • Energy from ETC used to PUMP H+ (fr. NADH) across membrane AGAINST GRADIENT. H+ ions then move down gradient thru. channel proteins called ATP synthase. • ATP synthase: enzyme that catazlyzes ADP + P --> ATP

Electron Transport Chain & ATP Synthase Summary: Use moving electrons to make ATP! Makes BULK of ATP (~34 ATP)

7.5: Cellular Respiration Energy stored in bonds of glucose --> ~ 38 ATP molecules Most ATP production occurs after glycolysis and REQUIRES OXYGEN.

7.5: Cellular Respiration

7.6: Anaerobic Respiration (Fermentation) Vocab.: FermentationAnaerobic Objectives: Explain how fermentation in muscle cells is different from cellular respiration. Give examples of products that depend on fermentation in microorganisms.

7.6: Fermentation What: Making ATP w/out O2 (using glycolysis) Context: Working muscles need an ongoing ATP supply; faster than O2 can be supplied for respiration. Yield: 2 ATPs for each glucose (but regular respiration is occuring @ same time too). Waste Product: Lactic Acid 2 Lactic acid

7.6: Fermentation in Humans After rigorous exercise, fermentation leads to a build up of lactic acid --> MUSCLE FATIGUE & SORENESS As your body converts lactic acid --> pyruvic acid you NEED OXYGEN and breathe heavily.

7.6: Fermentation in Microorganisms Yeast (fungi) cells can ferment sugar in anaerobic Environments (NoO2 ). Product of yeast fermentation is ETHANOL, an alcohol(not lactic acid) and CO2 .

7.6: Application of Fermentation • Production of: • Breads (CO2 makes break rise) • Alcoholic beverages • Yogurts and cheeses from milk (Fungi & bacteria that make lactic acid) • Soy sauce (fr. Soybeans) • Sauerkraut (fr. Cabbage)

Ch. 7.4: Cellular Respiration