Ch. 7.4: Cellular Respiration

Vocabulary

Aerobic Electron transport chain

Objectives:

1. Relate breathing and cellular respiration.

2. Summarize the cellular respiration equation.

3. Tell how “falling” electrons are a source of energy.

4. Explain the role of electron transport chains.

Ch. 7.4: Breathing & RespirationCellular respiration converts the energy stored in

food to energy stored in ATP.

Gases exchanged b/w blood & outside air via lungs.

Gases exchanged b/w cells & surroundings (blood or lymph)

Physical processes of

moving O2 & CO2 Chemical rxn involving the oxidation of glucose to H2O&

CO2

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?

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.

Moving to an outer energy level is like climbing uphill … it costs energy.

Moving to a lower energy level is like moving downhill.

7.4: Reacting with Oxygen; OxidationOxygen 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

Objectives:

1. Describe the structure of the mitochondrion.

2. Summarize the 3 stages of cellular respiration and identify where ATP is made.

Vocab:

Metabolism

Krebs Cycle

Glycolysis

ATP synthase

7.5: Mitochondia

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)!

Found in almost all eukaryotic cells.

2 membranes (inner & outer)

Inner membrane - highly folded w/ enzymes (ATP synthase) built in.

Thick fluid in matrix.

7.5: Steps of Cellular RespirationMetabolism: 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

•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

•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.

Electron Transport Chain & ATP SynthaseSummary: Use moving electrons to make ATP!

Makes BULK of ATP (~34 ATP)

7.5: Cellular RespirationEnergy 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:

1. Explain how fermentation in muscle cells is different from cellular respiration.

2. 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 (No O2 ).

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)