Cellular Respiration and Fermentation

How do plants and animals obtain the glucose they need?

Plants: Animals:

Cellular Respiration

● the process that releases energy from food in the presence of oxygen○ Oxygen must be available for use

Cellular Respiration Equation

6 O2 + C6H12O6 6 CO2 + 6 H2O + ATP

1st Reactant

Match each part of the Cellular Respiration equation

OxygenGlucoseCarbon Dioxide

ATPWater

2nd Reactant

1st Product

3rd Product

2nd Product

Remember!

We are not producing energy in cellular respiration

Instead, releasing it from organic molecules

Cellular Respiration Requirements

● Requires Oxygen and Glucose ○ Release CO2 and H2O

gradually ○ Must be gradual of energy

lost in form of light and heat■ There is a whole lot of

energy!!!

–http://www.youtube.com/watch?v=JOHdZsQXw7I

Stages of Cellular Respiration

● Glycolysis

● Krebs Cycle

● Electron Transport Chain

Step 1: Glycolysis

● Glucose is broken down in the cytoplasm

● Formed from each glucose○ 2 molecules ATP○ 2 molecules NADH ○ 2 pyruvate molecules

What is the yield of ATP for glycolysis?

Answer:

Step 2: Krebs Cycle (citric acid cycle)

● Pyruvate broken down into carbon dioxide during Krebs cycle

● Ultimate goal to make NADH and FADH2 for step 3 (electron transport chain)

Step 2: Krebs Cycle (citric acid cycle)

● Prior to the Krebs cycle pyruvate reacts with coenzyme A (CoA) to form Acetyl CoA○ Releases CO2 and NADH

● Acetyl CoA then moves to mitochondrial matrix

Step 2: Krebs Cycle (citric acid cycle)

● Krebs cycle begins with acetyl CoA combining with a 4-carbon compound to make 6-carbon citric acid

Step 2: Krebs Cycle (citric acid cycle)

● Citric acid is broken down ○ Releases 2 CO2○ Generates:

■ 1 ATP■ 3 NADH■ 1 FADH2

Step 2: Krebs Cycle (citric acid cycle)

● Remember: 2 molecules of pyruvate are formed ○ Krebs “turns” twice! ○

● For each glucose molecule the net yield is: ○ 6 CO2 ○ 2 ATP ○ 8 NADH ○ 2 FADH2

Needed for Next Step

Step 3: Electron Transport

● Step where most ATP is produced

● Electrons move along the mitochondrial membrane from one protein to another

Step 3: Electron Transport● As NADH and FADH2

release electrons, the H+ ions are released into mitochondrial matrix

● H+ ions are pumped across membrane

● Guess what it will be used for?

Step 3: Electron Transport

● ATP synthase is back again!

● Makes ATP when H+ diffuses down concentration gradient

Step 3: Electron Transport

● Electron transport chain produces: ○ 24 ATP ○ In eukaryotes one

molecules of glucose yields 36 ATP

Fill in the following blanks for cellular respiration.

2.

1. 2. 3.

Amoeba Sister’s Cellular Respiration

https://www.youtube.com/watch?v=4Eo7JtRA7lg

What if there isn’t enough oxygen!?

Anaerobic Respiration

● Occurs in low oxygen environments

● Some prokaryotes grow and reproduce without oxygen so they always do this!

Anaerobic Respiration - Fermentation

● Occurs in the cytoplasm and regenerates the cell’s supply of NAD+ while producing a small amount of ATP

● 2 types: ○ Lactic acid fermentation ○ Alcohol fermentation

Lactic Acid Fermentation

● Enzymes convert pyruvate from glycolysis to lactic acid

● Skeletal muscles do this during strenuous exercise when oxygen supply is low

Alcohol Fermentation

● Occurs in yeast and some bacteria

● Pyruvate converted to ethyl alcohol and CO2

Amoeba Sister’s Fermentation

https://www.youtube.com/watch?v=YbdkbCU20_M