Energy Releasing Pathways (Cell Respiration)

I. IntroductionA.

History1. A. Lavoisier in the 1700’s can make wine without living organisms

2. F. Wohler and J. von Leibig supported this idea, but T. Schwann showed juice would not ferment without yeast. 3. In 1860 L. Pasteur proved ethanol amount proportional to the amount of yeast present

4. In 1897 the E. Buchner brothers steps of glycolysis key to fermentation

5. In the early 1900’s A. Szent-Gyorgyi designed Citric Acid Cycle, failed to show relationship to fermentation6. H. Krebs in 1938 linked glycolysis to citric Acid Cycle via enzyme CoA Kreb’s Cycle

A. Overview

Figure 9.6

II. Aerobic Respiration

a. Cytosol

Figure 6.8 Figure 6.8

1. Where occurs?

B. Glycolysis

a. Components:

Figure 9.9

2. Steps and Players

ii. Splitting,

i. Investment,

& iii. Harvest

i. Investment1. Kinase enzyme attaches a P from ATP to glucose (6C) making glucose-PPrevents glucose from moving back out

of cell

3. Kinase enzyme attaches another P from second ATP to fructose-P, making P-fructose-P

Generates a balanced molecule with a P at either end.

2. Isomerase rearranges glucose-P into fructose-P (6C)Prepares molecule to add another

Phosphate

ii. Splitting1. Aldolase enzyme cuts molecule P-fructose-P into

two 3C moleculesG3P and Dihydroxyacetone-P2. Dehydrogenase enzyme liberates H and NAD+ steals

the electrons from HThis happens twice or once for each G3P3. The hole left by the leaving H is backfilled by Pi and

forms G1,3PThis step balances the two G3P’s with a P on both ends

How many NADH + H are formed per glucose?

iii. Harvest1. Kinase enzyme directly transfers a P from G3P to ADP to make ATP by substrate level phosphorylation (SLP)How many times does this happen to make how

many ATP’s?2. Mutase enzyme rearranges G3P into G2P

3. Enolase enzyme rearranges G2P into PEP

Prepares molecule for more harvest

Prepares molecule for more harvest

4. Kinase enzyme directly transfers a P from PEP to ADP to make ATP by SLP

Makes pyruvate out of each PEP

a. 2ATP are used by the cell.

b. NADH + H mitochondria and electron transport chain

The next two outcomes only happen if oxygen is present in the cell.

c. 2pyruvic acids are combined to CoA to go to the mitochondria and the Kreb’s cycle

3. Outcomes

a. Cytoplasm to Mitochondria

Figure 9.11

1. Where occurs?

2. Stepsa. Dehydrogenase enzymes splits off a CO2 from pyruvic acid which liberates electrons from H and given to NAD+ to make a 2C acetyl group b. Combine acetyl group to Co-enzyme A to be transported to the mitochondria

How many times this happen?

C. Transport

a. NADH + H mitochondria and electron transport chain

The next three outcomes only happen if oxygen is present in the cell.

b. 2pyruvic acids combined to 2CoA go to the mitochondria and the Kreb’s cycle

3. Outcomes

c. What is the fate of the CO2?

a. Mitochondrial Matrix

Figure 6.17

1. Where occurs?

D. Krebs Cycle

a. Divisions

Figure 9.12

2. Steps

i. Destroying

ii. Rearranging

i. Destroying1. Citrate synthase combines acetic group to oxaloacetic acid to begin cycle

2. Dehydrogenase enzymes splits out CO2 and liberates H to NAD+ How many CO2 are

liberated?3. As H’s are removed then a Pi jumps on only to be removed to form ATP by SLP

ii. Rearranging1. Mutase and dehydrogenase enzymes reshape

molecule to liberate more H’s to rebuild oxaloacetic acid2. Liberates H and NAD+ or FAD steals the electrons

This happens twice for glucose or once for each acetic group.

a. ATP is used

b. CO2 diffuses into cytosol and is lost

c. NADH + H and FADH2 are sent to electron transport chain

3. Outcomes

a. Inner Mitochondrial Membrane

Figure 6.17

1. Where occurs?

E. Electron Transport Chain

a. Divisions

2. Steps

i. Build-up &

Figure 9.13

ii. Harvest

Figure 9.14

Figure 9.15

i. Build Up

1. NADH and FADH2 drop the electrons from H to a series of re-dox proteins called cytochromes

2. As electrons move down the chain they lose energy which is used to move the H proton across the membrane to establish potential energy

ii. Harvest1. The electrons are eventually passed to an awaiting Oxygen atom2. The H proton moves back across the membrane through ATP Synthase and to the waiting O2 to form water 3. Conversion of energy (Potential to Kinetic) is used to form ATP

a. ATP is used

b. NAD+ and FAD+ sent back to glycolysis or the Kreb’s cycle

c. Water moved out or used

3. Outcomes

Summary of Aerobic Respiration

Figure 9.16

only glycolysis

A. Fermentation1.

Who?2. Process

Figure 9.17a

III. Anaerobic Respiration

Animal cells == lactic acid shuttle and Liver

Figure 9.17b

A. Lactic Acid Shuttle1.

Who?2. Process

Figure 9.19

A. Routes

B. Problems

IV. Versatility

Figure 9.20

A. Mechanisms

B. Sites

V. Regulation