CELLULAR RESPIRATION The process by which mitochondria break down food molecules to produce ATP.

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