Glycolysis & RespirationGlycolysis & Respiration

-Or-

How to release the energy stored in the glucose.

The Main GoalThe Main Goal ? ?

= To make as much ATP as possible!= To make as much ATP as possible!

Glucose (CGlucose (C66HH1212OO66))

• Recall that this molecule stored the energy of the sun in chemical form during photosynthesis.

• Now we have to release this energy so that it can be used efficiently.

• A fire releases this same energy but inefficiently (all at once) and much of the energy escapes as heat!

GlycolysisGlycolysis

• -lysis: to break down. Glyco- refers to the glucose.(remember Hydrolysis)

• Glycolysis breaks down glucose and gets it ready for the next step.

GlycolysisGlycolysis• Glucose 2 PGAL 2 Pyruvic Acids (6-Carbon) (3-Carbon) (3-Carbon)

• Draw Figure 4.10 on page 113 in text.Draw Figure 4.10 on page 113 in text.

• In the process of breaking glucose down from a six-carbon sugar to (2) three-carbon acids some energy is captured by the cell in the form of 6 ATP molecules.

• Remember, ATP is like the batteries for the cell.

NET ATP GAIN= 2 ATPNET ATP GAIN= 2 ATP

RespirationRespiration• Takes place in the mitochondria.

• Takes the pyruvic acidpyruvic acid from glycolysis and gets more energy out of it.

• First changes Pyruvic acid (a 3-carbon compound) and drops off a carbon dioxide molecule leaving the 2-carbon molecule called acetic acidacetic acid..

• (Where have you heard of that before?)

Vinegar!Vinegar!

Respiration—Kreb’s CycleRespiration—Kreb’s Cycle• In the Krebs Cycle acetic acid (yuk!) is first

changed into citric acid.• (Where have you heard of that before?)• From here it goes through a number of steps

which release CO2 and high energy compounds like NADH (no P), and FADH2.

• Kreb’s produces the CO2 that you exhale.

Citrus fruit (much better!)

RespirationRespiration

• This is the beginning of

Pyruvic Acid -C3

Acetic Acid -C2

CO2

Citric Acid -C6

C4

From glycolysis

Citric Acid -C6

CO2

C5

CO2

C4

C4Changes its structure

C4

C4

Changes its structure

C4

Acetic Acid -C2Changes its structure

Changes its structure

Citric Acid -C6

C5

CO2

CO2

C4

C4

C4

C4

C4

Acetic Acid -C2

NAD+

NADH

NADH

NAD+

GDPGTPFAD+

FADH2

NAD+

NADH

• As a result

– 2 CO2 are given off

– 3 NADH are made

– 1 FADH2 is made

– 1GTP is made

These are high energy molecules that will go to make ATP molecules

NET ATP GAIN = 2 ATPNET ATP GAIN = 2 ATP

RespirationRespiration

• The final electron acceptor is oxygen.

• When glycolysis and respiration are finished the result is that 36 ATP molecules have been produced.

Total Breakdown of GlucoseTotal Breakdown of GlucoseGlucose

Glycolysis

Pyruvic Acid

Kreb’s Cycle

ETC

2 ATP

2 ATP

32 ATP !!!

TOTAL =TOTAL =

36 ATP FOR 36 ATP FOR EVERY EVERY GLUCOSE.GLUCOSE.

Only when OOnly when O22 is present is present

RespirationRespiration

• The overall reaction for The overall reaction for respirationrespiration is: is:

C6H12O6 + 6O2 6CO2 + 6H2O

• The overall reaction for The overall reaction for photosynthesisphotosynthesis was was:

6CO2 + 6H2O C6H12O6 + 6O2

ComparisonsComparisons• Photosynthesis has two reactions called the light and

dark reactions.• The dark (light independent) reaction of

photosynthesis was called the Calvin Cycle because it had no clear cut end product.

• Energy production is broken down into two reactions - glycolysis and respiration.

• Respiration can also be called the Krebs (or citric acid) Cycle because there is no clear cut end product.