Cellular RespirationCellular Respiration

Cellular Respiration…What is it?Cellular Respiration…What is it?

-process by which cells make ATP by -process by which cells make ATP by breaking down organic compunds.breaking down organic compunds.

Why is it important?Why is it important?

-cells need usable forms of energy to -cells need usable forms of energy to function and maintain homeostasis.function and maintain homeostasis.

It all starts with: It all starts with: GlycolysisGlycolysis Cellular Respiration begins with a biochemical Cellular Respiration begins with a biochemical

pathway called glycolysis. (no oxygen is present.)pathway called glycolysis. (no oxygen is present.)

-one glucose molecule is broken down -one glucose molecule is broken down (oxidized) to produce two molecules of pyruvic (oxidized) to produce two molecules of pyruvic acid.acid.

-The net yield of glycolysis is two ATP -The net yield of glycolysis is two ATP molecules. molecules.

-After glycolysis, the oxidation process -After glycolysis, the oxidation process continues in the continues in the presencepresence or or absenceabsence of oxygen. of oxygen.

Fermentation (Anaerobic)Fermentation (Anaerobic) no no oxygenoxygen Fermentation occurs after glycolysis when Fermentation occurs after glycolysis when

oxygen is absent within the cells.oxygen is absent within the cells.

-No ATP is generated. However, NAD-No ATP is generated. However, NAD++ is is regenerated which is needed in glycolysis. regenerated which is needed in glycolysis.

-Two common fermentation pathways:-Two common fermentation pathways:

1. Lactic Acid Fermentation1. Lactic Acid Fermentation

2. Alcoholic Fermentation2. Alcoholic Fermentation

1. Lactic Acid Fermentation1. Lactic Acid Fermentation

Enzymes convert pyruvic acid into Enzymes convert pyruvic acid into lactic acid. lactic acid.

-Lactic Acid Fermentation is -Lactic Acid Fermentation is important in the manufacturing of important in the manufacturing of various foods. (yogurt, cheese)various foods. (yogurt, cheese)

-Athletes also experience Lactic Acid -Athletes also experience Lactic Acid buildup…cramping and fatigue. buildup…cramping and fatigue.

2. Alcoholic Fermentation2. Alcoholic Fermentation

Enzymes convert pyruvic acid into Enzymes convert pyruvic acid into ethyl alcohol.ethyl alcohol.

-Process is done by some plants and -Process is done by some plants and yeast.yeast.

-This process is important in the -This process is important in the bread, beer and wine industry.bread, beer and wine industry.

Aerobic RespirationAerobic Respiration oxygen oxygen

presentpresent Occurs in the presence of oxygen. Occurs in the presence of oxygen. Net ATP production is much greater!Net ATP production is much greater!

Two major steps:Two major steps:1. Krebs Cycle (citric acid is formed)1. Krebs Cycle (citric acid is formed)2. Electron Transport Chain2. Electron Transport Chain

In prokaryotes, occurs in the cytoplasm.In prokaryotes, occurs in the cytoplasm. In eukaryotes, occurs in the mitochondria. In eukaryotes, occurs in the mitochondria.

Krebs Cycle Krebs Cycle (Citric Acid Cycle)(Citric Acid Cycle)

When pyruvic acid enters the When pyruvic acid enters the mitochondria, acetyl CoA is formed. mitochondria, acetyl CoA is formed.

The Krebs Cycle breaks down the acetyl The Krebs Cycle breaks down the acetyl CoA producing COCoA producing CO22 , hydrogen atoms, , hydrogen atoms, and ATP. (NADH, FADHand ATP. (NADH, FADH22))

Each glucose molecule yields only two Each glucose molecule yields only two molecules of ATP through the Krebs molecules of ATP through the Krebs Cycle.Cycle.

Electron Transport ChainElectron Transport Chain So far, not much ATP has been produced. The So far, not much ATP has been produced. The

Krebs Cycle produces NADH and FADHKrebs Cycle produces NADH and FADH22 which which drives the Electron Transport Chain.drives the Electron Transport Chain.

Occurs in the membrane of the mitochondria. Occurs in the membrane of the mitochondria. After the ATP is produced, it diffuses into the After the ATP is produced, it diffuses into the cytoplasm.cytoplasm.

ATP is produced by the release of hydrogen ATP is produced by the release of hydrogen atoms from NADH and FADHatoms from NADH and FADH22. (chemiosmosis). (chemiosmosis)

Oxygen is necessary and ends up forming water. Oxygen is necessary and ends up forming water.

Final Thoughts…Final Thoughts… Net production of ATP through aerobic Net production of ATP through aerobic

respiration…36 ATP. respiration…36 ATP.

The oxidation of glucose can be The oxidation of glucose can be summarized in the following equation:summarized in the following equation:

CC66HH1212OO66 + 6O + 6O22 → 6CO→ 6CO22 + 6H + 6H22O + energy O + energy (ATP)(ATP)

Not only does Cellular Respiration provide Not only does Cellular Respiration provide ATP, it also makes carbon ‘skeletons’ that ATP, it also makes carbon ‘skeletons’ that can be made into larger molecules needed can be made into larger molecules needed by the cells.by the cells.