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