Cellular Respiration

Cellular Respiration The process by which the mitochondria

breaks down glucose to produce ATP is called cellular respiration.

C6H12O6 + 6O2 6CO2 + 6H2O + Energy

How much energy is actually present in food?

1 gram of sugar glucose, when burned in the presence of oxygen, releases 3811 calories of heat energy!

Cellular Respiration

calorie- the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

“C” or Calorie used on food labels = 1000 calories (kilocalorie)

Cellular Respiration

Cells release the energy from glucose and other food components (they don’t burn it)

Cellular Respiration

Cellular Respiration When the body has oxygen, aerobic

respiration can take place and produce 36 ATP molecules.

There are 3 stages of aerobic respiration: Glycolysis Krebs cycle (aka Citric Acid

Cycle) Electron transport chain

THE BIG PICTURE

Glycolysis

Glycolysis takes place in the cytoplasm of the cell.

Glycolysis Glycolysis is the process where glucose is broken

down in 2 pyruvic acid molecules. Pyruvic acid is a 3 carbon molecule.

The net gain of ATP molecules in glycolysis is 2 ATP molecules.

4-22

Glycolysis Following glycolysis, the pyruvic acid moves

into the mitochondria.

The Krebs Cycle

The Krebs cycle takes place in the MATRIX! Pyruvic acid enters the Krebs cycle and

becomes broken down. As this occurs, 2 carbon dioxide molecules are released.

In addition, 2 ATP molecules are released. Electron carriers such as FAD and NAD are

used to pick up energized electrons and pass them to the ETC.

AKA

Citric Acid Cycle

The Krebs Cycle AKA

Citric Acid Cycle

Krebs Cycle

Electron carriers

FYI: Flavin adenine dinucleotide Nicotinamide adenine dinucleotide

The Electron Transport Chain The last step of respiration is the electron

transport chain or ETC. It takes place in the inner membrane. In the presence of oxygen, the electron

transport chain will produce 32 ATP molecules and water.

The total of ATP molecules released from AEROBIC respiration is 36.

Electron Transport Chain

Animation: http://www.science.smith.edu/departments/Biology/Bio231/etc.html

http://vcell.ndsu.nodak.edu/animations/etc/movie.htm http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter9/animations.html#

Electron carriers NADH and FADH2 release the Hydrogen ions across the membrane. This creates a concentration gradient.

When oxygen enters the ETC, it becomes the final electron acceptor of the Hydrogens and creates H2O.

As the hydrogen ions come back across the membrane, ADP is converted into ATP.

Electron Transport Chain

Electron carriers NADH and FADH release the Hydrogen ions to proteins to cross the membrane. This creates a concentration gradient.

When oxygen enters the ETC, it becomes the final electron acceptor of the Hydrogen ions and creates H2O.

As the hydrogen ions come back across the membrane, ADP is converted into ATP.

THE BIG PICTURE

Cellular respiration

Anaerobic Resp

There are times when cells are without oxygen for a short period of time. When this happens, anaerobic respiration is taking place.

In anaerobic respiration, glycolysis takes place; then followed by one of two pathways: Lactic Acid Fermentation or

Alcoholic Fermentation. Total ATP molecules released = 2.

AKA

Fermentation

Aerobic: presence of oxygen

Anaerobic: absence of oxygen

Ferm

enta

tion Aerobic

respiration

Types of Anaerobic Respiration When our cells run out of oxygen and begin

fermentation, we build up lactic acid. That lactic acid build up in the muscle makes us feel a cramp and burning sensation.

C6H12O6 ATP + lactic acid

fermentation

Types of Anaerobic Respiration Some fungi also undergo fermentation.

They release ethyl alcohol and carbon dioxide.

C6H12O6 ATP + CO2 + ethyl alcohol This process is key for the yeast that create

wine and other alcoholic beverages.

Types of Anaerobic Respiration Yeast undergo this type of fermentation when

making bread.

fermentation

Comparing Photosynthesis and Respiration

Photosynthesis Respiration

• Glucose made• Light energy required• ATP broken down in 2nd

phase of p.s.• CO2 taken in• O2 released• Needs water• Takes place in

chloroplast• Takes place in

autotrophs

• Glucose broken down• Light is not required• Energy created in ATP• CO2 released• O2 taken in• Water released• Takes place in

mitochondria• Takes place in all

organisms

• Require use of ATP molecules• Take place in plants• Necessary to sustain all life on earth