QOD – What is the fuel of the cell called?

9.3

Cellular Respiration - is the process by which mitochondria break down food molecules to produce ATP.

Three Phases:

Glycolysis, citric acid cycle, and ETC

Glycolysis is a series of chemical reactions in cytoplasm of a cell that break down glucose (6 carbon) into 2 molecules of pyruvic acid (3 carbon)

Requires 2 molecules of ATP to start glycolysis

Breaking down of glucose into pyruvic acid produces 4 ATP and 2 NADH and 2H+

Anaerobic stage - doesn’t require oxygen

Glucose

2 ATP 2 ADP

c

P2

2 NAD + 2 NADH + 2H + 4 ATP 4 ADP

2 Pyruvates

2 ATP – Needed to start Glycolysis 2 NADH Produced 4 ATP Produced

Net Totals: 2 NADH 2 ATP

NAD+ is an electron carrier

Created during glycolysis when Glucose is broken down into pyruvic acid

Two energized electrons are added to NAD+ to create NADH and H+

Glycolysis Movie

The two molecules of pyruvic acid enter the mitochondria

They undergo a series of reactions before moving on to the second stage, citric acid cycle

Pyruvic acid is changed in a series of reactions Releases CO2

Joins with Coenzyme A

End result is acetyl-CoA (2 Carbon) Produces one NADH and H+

NAD+ NADH + H+

CO2

Also called the Krebs Cycle

Aerobic reaction - needs oxygen to occur

Is a series of chemical reactions (similar to the Calvin Cycle) in which the molecule used in the first reaction is the end product.

End result for 1 cycle:

1 ATP

3 NADH

1 FADH2

3 H+

The electron carrier molecules NADH and FADH2 take the energized electrons to the ETC

Found in the inner membrane of the mitochondria

1. Acetyl-CoA enters the Krebs Cycle and combines with the oxaloacetic acid (4carbon) to form citric acid (6 carbon)

2. Citric acid (6 carbon) releases a carbon to form CO2 and in the process creates NADH and H+. End result is a 5 carbon structure.

3. A second CO2 is produced when the 5 carbon structure releases a carbon and in the process ATP and NADH and H+ are produced. End result is a 4 carbon structure.

4. The 4 carbon structure goes through a series of reactions to reform oxaloacetic acid to ensure the cycle is able to continue.

5. 1st reaction - produces a FADH2

6. 2nd reaction - no byproducts

7. 3rd reaction - NADH and H+ form

8. Formation of Oxaloacetic acid

Video

Location: inner membrane of Mitochondria NADH and FADH2 take the energized

electrons to the ETC Electrons are passed from protein to

protein in the ETC slowly releasing their energy in steps Some can be used to form ATP

Some can be used by an enzyme to pump H+ ions into the center of the mitochondria

Aerobic reaction - requires oxygen to occur

The inner membrane becomes positively charged

The exterior membrane becomes negatively charged

Which attracts H+ ions(because they are positive)

The gradient of H+ ions created provides the energy needed to create ATP

The final electron acceptor is oxygen which forms 2 waters, when oxygen reactions with four H+ and 4 electrons (lost their energy)

Why we need oxygen, otherwise we would have a build up of electrons, until the ETC could no longer accept anymore electrons and would no longer function

Overall the ETC produces

32 ATP

Water

NAD+

FAD+

ETC in cellular respiration

Cellular Respiration creates

36 ATP

6 NADH

1 FADH2

3 CO2

H2O

6 H+

An anaerobic process that occurs in the absence of oxygen for short periods of time that allows ATP to be created until oxygen can be restored

During heavy exercise

Two major types

Lactic Acid Fermentation

Alcoholic Fermentation

Lactic Acid Alcoholic Cellular Respiration

Glucose Glucose Glucose

Glycolysis Glycolysis Glycolysis

CO2 CO2

Lactic acid alcohol Carbon dioxide + water

2 ATP 1 ATP 36 ATP

Process that supplies energy when oxygen is limited

Without oxygen the ETC begins to back up and it can no longer accept electrons

Therefore there is no NAD+ or FAD+ to supply to the citric acid cycle or glycolysis

NAD+ can still be created without oxygen but FAD+ can not

Two molecules of pyruvic acid use NADH to form 2 molecules of lactic acid

This release NAD+ which can be used in glycolysis allowing 2 ATP

During extreme exercise muscle cells produce lactic acid, but after it is used to create NAD+ it travels to the liver to be turned back into pyruvic acid

Lactic acid build up in the muscle cells causes muscle fatigue and soreness

Alcoholic fermentation is used by yeast and some bacteria cells to produce CO2 and ethyl alcohol.

Yeast - used to make bread rise by releasing CO2. The heat from baking does kill the yeast.

Bacteria - used to create alcohol from fruits and plants

Similarities

Both use ETC

Both use cycles of chemical reactions to form ATP

Both create a concentration gradient of H+ by using a Hrydrogen ion pump

Both utilize PGAL

Differences:

Cellular Res.

Produces ATP

Gives off CO2

Doesn’t require light

Occurs in plants and animals

Energy carrier NADH and FADH2

Photosynthesis

Produces Glucose

Requires light

Gives off oxygen

Occurs only in plants or cells with chlorophyll

Energy carrier NADPH