000D8CF8/FOV1-000E9546/FOV1- 000E954C/Krebs%20Cycle.pdfhttp://chatt.hdsb.ca/~duncand/FOV1- 000D8CF8/FOV1-000E9546/FOV1- 000E954C/Krebs%20Cycle.pdf

Cellular Respiration

The Mitochondria

What characteristics do you notice about the mitochondria? What features does it have?

Mitochondrial Structure

Mitochondrion vs. Chloroplast What do they have in common? What appears different?

Both have their own DNA Both are small like prokaryotes Both make energy

Why are mitochondria important? All cells require energy in the form of _______. Mitochondria are the “powerhouses” that supply that energy by performing cellular respiration

What is Cellular Respiration? Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. all eukaryotic cells* Takes energy from food (glucose) and turns it into a form cells can use ( ATP )*.

O2O2 CO 2 Lungs CO 2 O2O2 Bloodstream BREATHING CELLULAR RESPIRATION

Cell Respiration Equation 6O 2 + C 6 H 12 O 2  6CO 2 + 6H 2 O + Energy* Oxygen + Glucose  Carbon Dioxide + Water + Energy Does this equation look familiar? It should- It is the reverse of photosynthesis!

Parts of Cellular Respiration Cell Resp. is broken into three parts:* – 1. Glycolysis – 2. Kreb’s Cycle – 3. Electron Transport Chain Each stage uses chemical energy to make ATP.

Step 1 - Glycolysis One molecule of glucose is broken in half, producing two 3- carbon molecules called pyruvic acid (pyruvate). –2 ATP and 2 NADH are generated Occurs in ______________. Cytoplasm

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? Glycolysis Kreb’s Cycle Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose Kreb’s Cycle Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH Kreb’s Cycle Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Kreb’s Cycle Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle Electron Transport Chain

Cell Resp. – Why is it important? Cells require energy (ATP) to function Glucose holds energy, but it must be “released” and converted to ATP for cells to use Cellular respiration is the conversion of glucose to ATP

Glycolysis – Why is it important? Glycolysis is the first step in converting glucose to ATP Glucose is split up into two molecules of pyruvate –It takes 2 ATP to do this

Glycolysis From glycolysis we get: –2 molecules of ATP for instant use* –2 molecules of NADH for ETC use NADH holds high energy e-* –2 molecules of pyruvate produce *

Advantages Fast Doesn’t require oxygen Disadvantages Cell’s NAD+ gets used up so quickly, glycolysis can’t go on for long Doesn’t make all that much ATP

After Glycolysis… Glycolysis Fermentation Alcoholic Fermentation Lactic Acid Fermentation Kreb’s Cycle Electron Transport Chain Oxygen present No oxygen present Two Choices: (Respiration) Fermentation = No ATP Respiration = Lots of ATP

Fermentation When no oxygen is present, glycolysis is followed by fermentation rather than the Kreb’s cycle Fermentation creates more electon carries (NAD+) so that glycolysis can make more ATP*

Fermentation Fermentation converts NADH to NAD+ – Frees up NAD+ so glycolysis can continue and make more ATP Fermentation is anaerobic* – Does not require oxygen*

Types of Fermentation Alcoholic Fermentation (yeast* & bacteria) –Used to make cheese, bread, wine, buttermilk, etc.. Pyruvate + NADH  alcohol + CO 2 + NAD+*

Types of Fermentation Lactic Acid Fermentation (bacterial & muscle cells, –When muscles don’t get enough oxygen, lactic acid fermentation occurs –Build up of lactic acid makes muscles sore *pyruvate + NADH  lactic acid + NAD+

The Rest of Cell Respiration If oxygen is present, the cell performs cellular respiration After glycolysis, 90% of the energy from glucose is still unused Final two steps in cell respiration extract that energy using oxygen –AEROBIC processes = require oxygen

Step 2 - The Kreb’s Cycle Summary: –During the Kreb’s cycle, pyruvate is broken down into CO 2 + energy (NADH)* The Kreb’s cycle takes place in the matrix* of the mitochondria Matrix

Kreb’s Cycle Pyruvic acid enters the mitochondrial matrix One carbon molecule is lost as CO 2 while NAD+  NADH Remaining two carbon molecules combine with coenzyme A to form acetyl CoA

Kreb’s Cycle a.k.a Citric Acid Cycle

Kreb’s Cycle Acetyl CoA is turned into CITRIC ACID. –Kreb’s Cycle a.k.a. Citric Acid Cycle Citric acid is broken down and two CO 2 molecules are released During this process, energy is released in the form of 8 NADH, 2 FADH 2, and 2 ATP* The remaining molecule, OXALOACETIC ACID (OAA), is used to restart the cycle.

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6CO 2 (waste) OAA Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? Kreb’s Cycle 2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> ETC OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain

Krebs Results From all this we got 3 different forms of energy: 1.ATP – immediate cell usage 2.NADH 3.FADH 2 Electron carriers that will bring high-energy electrons to ETC

Step 3 – Electron Transport Chain What did the ETC do in photo- synthesis?

Step 3 – Electron Transport Chain (ETC)Electron Transport Chain (ETC) The electron transport chain uses high-energy electrons from the Kreb’s cycle to make ATP Occurs in ____________________.* Cristae (inner membrane) Cristae (inner membrane)

Electron Transport Chain Electrons from NADH and FADH 2 are transported to the ETC* At the end of the ETC sits oxygen*, which is very electronegative (it draws electrons near it) - this causes the electrons to travel down the ETC towards oxygen –Oxygen is the terminal electron acceptor At the end of the chain, a protein combines the electrons with H + and O - to make H 2 O*

Electron Transport Chain Every time 2 electrons move down the ETC, their energy pumps H+ ions into the inner membrane space, creating a concentration gradient* The H+ ions then want to diffuse from the inner membrane space back to the matrix* Meanwhile…

Electron Transport Chain To cross the membrane, H+ moves through ATP synthase molecules making a gradient with the H+ * – Each time they do, it creates ATP – Chemiosmosis* Each pair of electrons yields 3 ATP molecules

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> Electron Trans. Chain OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> Electron Trans. Chain OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain NADH FADH 2

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> Electron Trans. Chain OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain NADH FADH 2 32 ATP

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> Electron Trans. Chain OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain NADH FADH 2 32 ATPH20H20

Cell Respiration Overview Respiration Stage ReactantsEnergy Products Other Products Next Stop? GlycolysisGlucose 2 ATP 2 NADH 2 Pyruvate Pyruvate--> Kreb’s cycle NADH--> Electron Trans. Chain ATP--> Cell use Kreb’s Cycle2 Pyruvate 2 ATP 8 NADH 2 FADH 2 6 CO 2 (waste) OAA CO 2 --> breath NADH & FADH 2 --> Electron Trans. Chain OAA --> restart Kreb’s ATP--> cell use Electron Transport Chain NADH FADH 2 32 ATPH20H20 ATP--> Cell use H 2 0--> NAD+ & FAD+ --> recycled

The Totals Glycolysis ? ATP Kreb’s Cycle & Electron Transport ?? ATP _______ Total ?? ATP

The Totals Glycolysis 2 ATP Kreb’s Cycle & Electron Transport ?? ATP _______ Total ?? ATP

The Totals Glycolysis 2 ATP Kreb’s Cycle & Electron Transport 34 ATP _______ Total ?? ATP

The Totals Glycolysis 2 ATP Kreb’s Cycle & Electron Transport 34 ATP _______ Total 36 ATP

Think about it… What types of cells can perform cellular respiration: –Animal cells? –Plant cells? –Bacterial cells? –Yeast cells? –Anything else you can think of?

Think about this one… In what situations would a cell perform fermentation over respiration? Explain.

Think About This One! Why might you lose weight (a lot of weight) if your mitochondria suddenly lost the ability to couple electron transport to the production of ATP?

Comparison of Fermentation to Cellular Respiration Lactic Acid AlcoholicCellular respiration glucose glycolysis (pyruvic acid) lactic acid 2 ATP glucose glycolysis (pyruvic acid) carbon dioxide alcohol 2 ATP 36 ATP water carbon dioxide Cellular Respiration vs. Fermentation

How Do Other Food Molecules Enter Metabolism? Fat, carbohydrates and proteins enter the cellular respiration pathway at different points The most likely point is at acetyl CoA

Overall Cell Respiration