CELLULAR RESPIRATION

The process by which mitochondria break down food

molecules to produce ATP

There are three stages.

1.Glycolysis2.Citric acid cycle3.E-transport chain

GLYCOLYSIS

• Overview: series of chemical reactions in the cytoplasm of cells that break down GLUCOSE(C6H12O6) into two-three carbon molecules called pyruvic acid.

• 2 ATP are required to start glycolysis• Glycolysis is inefficient because it only

produces 4 ATP and has to use two to get going. Leaving a net ATP of 2 for each molecule of glucose broken down.

Two Kinds of Glycolysis

• Anaerobic (W/O O2)– Prokaryotic– Typically bacteria– Fermentation- which

produces ethyl alcohol and then breaks down into lactic acid

• Aerobic ( with O2)– Eukaryotic– Glycolysis-4 ATP– Kreb’s Cycle-2 ATP– E- transport – 32 ATP

– Cellular Respiration: Max Produced 38 ATP/molecule of glucose. Usable is 36

Step 1

• 2 phosphate groups are attached to glucose(6 carbon sugar)

• 2 ATP’s are broken down to supply phosphates

• P-C-C-C-C-C-C-P

Step 2

• 6 Carbon molecule is split into (2)3 Carbon molecules

• C-C-C-P

• C-C-C-P

STEP 3

• C-C-C-P(1st PGAL) Oxidized• C-C-C-P(2nd PGAL) Oxidized• 2NAD+(nicotinamide adenine dinucleotide) are

reduced (accepts e-),carries it becoming 2NADH + (2H+)

NAD is a coenzyme that accepts e- and p+

2 Phosphates are added to becomeP-C-C-C-P and P-C-C-C-P

Step 4

• Phosphates added in Step I and 3 are removed

• Leaving 2 molecules of pyruvic Acid

C-C-C and C-C-C

The 4 phosphates are combined with molecules of ADP to form 4 ATP’S

ATP TOTAL SO FAR

• 4 ATP are produced at the end of glycolysis.

• 4 ATP – 2 ATP= net of 2 ATP going into the citric acid cycle

The Citric Acid Cycle or Kreb’s Cycle

• Where: Mitochondria

• Who: All living things

• When: Always going on

• Why: Produce ATP

Electron and Proton Carriers

• FAD(flavin adenine diphosphate)

• NAD(nicotinamide diphosphate)

• A total of 3 NADPH molecules are formed and 1 FADH2 molecule is formed

• These e-carriers transport energized e- from the citric acid cycle to the electron transport chain in the inner membrane of the mitochondrion

STEP 1

• Pyruvic acid: (Product of glycolysis) (2C2H3OCOOH) reacts with coenzyme A

to form

• Acetyl Coenzyme A or

Acetyl CoA

• C-C-CoA

STEP 2

• C-C-CoA combines with oxaloacetic acid

(C4H4O5) and forms Citric Acid

A 6 carbon compound

CO2 is released and a H+ is released

H+ joins with NAD(an enzyme that accepts e- and H+) to form NADH+

The 6 Carbon compound is now a 5 carbon compound called ketoglutaric acid

STEP 3

• The Ketoglutaric acid loses a CO2 and a H+ ion and becomes a 4 carbon compound. C-C-C-C (Succinic Acid)

• The H+ joins with a NAD and forms NADH

• One ATP forms here

STEP 4

• Succinic Acid Loses a H+ and breaks down into Fumaric acid, another 4 carbon compound

• This H+ hooks up with FAD(flavin adenine dinucleotide) another enzyme to create FADH

Another H+ attaches to FADH and becomes FADH2+

Step 5

• Fumaric Acid breaks into another 4 carbon compound called Malic acid

• NADH and FADH are used to regenerate Oxaloacetic acid and the cycle begins again

Part 3 : The Electron Transport Chain

• Where: inner mitochondrion membrane• NADH and FADH2 Pass energized e- from

protein to protein within the membrane.• Releasing energy along the way• Some of that energy is used to create ATP

and some is used to pump H+ ions into the center of the mitochondrion

• Inside the membrane is + charged and outside is - charged

Electron Transport Continued

• The inner membrane forms ATP from this electrochemical gradient across the mitochondrial membrane.

• The final electron acceptor is Oxygen Which reacts with 4 H+ to form 2 H2O’s

• The e- transport chain produces 32 ATP’s• 32 ATP + 2 ATP in Kreb’s + 2 from

glycolysis = 36 total ATP’s produced in cellular respiration

Comparison of photosynthesis and Cellular Respiration

• Photosynthesis– Food accumulated– Energy from sun stored in

glucose– Carbon dioxide taken in– Oxygen given off– Produces glucose from

PGAL– Goes only in light– Occurs in the presence of

chlorophyll

• Cellular Respiration– Food broken down– Energy of glucose is

released– CO2 given off– Oxygen taken in– Produces CO2 and H2O– Goes on all day and night– Occurs in living cells