Cellular Respiration

Essential Questions:

How is the energy in our food released?

How does aerobic respiration and anaerobic respiration compare and contrast?

What are the 2 types of anaerobic respiration?

How are the processes of photosynthesis and cell respiration different?

Cellular Respiration

• Cellular Respiration = Process by which mitochondria break down food molecules to produce ATP

• Does not use Oxygen is called Anaerobic

• Does use Oxygen is called Aerobic

• There are 3 stages of Cellular Respiration:

1) Glycolysis (Anaerobic)2) Citric Acid Cycle (Aerobic)3) Electron Transport Chain (Aerobic)

Glycolysis - Anaerobic• Glycolysis = series of chemical

reactions in the cytoplasm of a cell that break down glucose (a 6 Carbon compound) into 2 molecules of pyruvic acid (a 3 Carbon compound)

• NAD+ accepts a pair of high energy electrons to pass that energy to other pathways in the cell.

• 2 Molecules of ATP are used to start Glycolysis and only 4 ATPs are produced

• Net only 2 ATP• Then pyruvic acid proceeds to the

Mitochondria to begin the Citric Acid Cycle and the Electron Transport Chain (in the presence of Oxygen)

Anaerobic Processes • Sometimes your cells are without

Oxygen for short periods of time (during strenuous exercise, etc)

• In order to make ATP, the process of Fermentation occurs after Glycolysis until Oxygen becomes available again.

• During fermentation, cells convert NADH to NAD+ by passing high energy electrons back to pyruvic acid. This action converts NADH back into the electron carrier NAD+ allowing glycolysis to continue producing a steady supply of ATP.

• Some organisms simply live in areas without Oxygen and must produce their ATP this way.

• http://www.youtube.com/watch?v=y_k8xLrBUfg

2 Anaerobic Processes:Lactic Acid Fermentation & Alcoholic Fermentation

• Without Oxygen, the Electron Transport Chain becomes backed up since no Oxygen is there to be the final electron acceptor

• Pyruvic Acid + NADH → lactic acid + NAD+• Lactic Acid is the cause of

sore muscles.

• Certain organisms living in anaerobic environments will rely on this type of ATP synthesis.

• Pyruvic acid + NADH →

alcohol + CO2 + NAD+

• Yeast use this type of fermentation to create C02 and ethyl alcohol.

Aerobic Respiration

• Most efficient type of Cellular Respiration!

• Requires Oxygen• Occurs in 3 steps:

– 1) Glycolysis– 2) Citric Acid Cycle– 3) Electron Transport Chain

• Glycolysis is the only step that is Anaerobic.

• The other Anaerobic process was fermentation.

Aerobic Respiration - Mitochondria• Remember, Glycolysis breaks

down 1 glucose into 2 pyruvic acid molecules

• Heads to Mitochondria for Aerobic Respiration

• Citric Acid Cycle occurs in the outer mitochondrial membrane

• Calvin Cycle – glucose was formed

• Citric Acid Cycle – glucose is being broken down

• For 1 Glucose molecule, 1 ATP is made for every turn of the cycle.

• http://www.wiley.com/college/pratt/0471393878/student/animations/citric_acid_cycle/index.html

Electron Transport Chain 1:2• Very Similar to the ETC of the

thylakoid in plants!• NADH and FADH2 pas

energized electrons from protein to protein releasing small amounts of energy.

• A Concentration gradient forms in the mitochondria – Hydrogen ions inside– Lack of Hydrogen ions

outside• An Electrical gradient forms in

the mitochondria (H+ ions pumped inside)– Positive in the center– Negative on the outside

Electron Transport Chain 2:2

• The final electron acceptor is Oxygen

• Yields Carbon Dioxide (CO2), 2 Water, and 36 ATP

• Most efficient process since anaerobic respiration only yields 2 ATP. • http://www2.nl.edu/jste/electron_transport_system.htm

What type of protein am I?

An Enzyme!

Overview of Cellular RespirationLabel the picture on your notes!

Comparing Photosynthesis & Respiration

• PHOTOSYNTHESIS– Food accumulated– Energy from the Sun

stored in Glucose

– CO2 taken in

– Oxygen given off– Produces Glucose from

PGAL– Goes on only in Light– Occurs in the presence

of Chlorophyll of Plants only

– Chloroplasts

• RESPIRATION– Food Broken Down– Energy of Glucose

Released

– CO2 given off

– Oxygen taken in– Produces Carbon Dioxide,

Water & ATP– Goes on Day & Night– Occurs in all Living Cells

(Plants and Animals)– Mitochondria