1. Glycolysis

2. Four Main Stages of Cellular Respiration• 2. 3.
1. Glycolysis
Anaerobic In cytosol
breaks glucose (6C) into 2 pyruvate molecules (3C)
releases ATP
2. Pyruvate Oxidation
(oxidative decarboxylation
Pyruvate converted to acetyl CoA releasing CO2
3. Kreb’s Cycle
Within mitochondrial matrix Oxidize each acetyl CoA to CO2
Releases ATP and co-enzymes (NADH, FADH2)
4. Electron Transport Chain
Along the inner mitochondrial membrane
Uses high energy electrons from NADH and FADH2 to create an electrochemical proton (H+) gradient which powers ATP synthesis

3. o glyco- “sugar”, and –lysis to break apart
Glycolysis
o glyco- “sugar”, and –lysis to break apart
First step of both anaerobic and aerobic cellular respiration
No oxygen required for this step (anaerobic)
Occurs in the cytosol of the cell
Each step catalyzed by a specific enzyme
Energy (2 ATP) is required to start this process and 4 ATP is eventually produced
Net: 2 ATP
Glucose is broken down into 2 pyruvates

4. Cellular Respiration
The set of metabolic reactions that take place in the cells of an organism to convert biochemical energy from nutrients into ATP, and then release waste products.
catabolic
exergonic
series of reactions to allow for slow, useable release

5. Glycolysis: A Central Pathway
Glycolysis (glyco - glucose, lysis - dissolving) is a pathway that occurs (with variation) in nearly every living organism on earth. It is a sequence of 10 enzyme catalyzed reactions that ultimately converts glucose to pyruvate. The intermediates provide entry and exit points for metabolism of other organic molecules.
Each black arrow on the diagram represents a different enzyme catalyzed reaction. Major intermediates are shown, along with connected pathways.

6. Anaerobic vs. Aerobic
An anaerobic reaction is one that takes place without oxygen. Glycolysis is anaerobic, and takes place in the cytoplasm.

7. Pyruvate
One of the major products of glycolysis, pyruvate, is a three carbon molecule.
Depending on the organism, the cell type, and the situation, this can be metabolized further in either the presence (aerobic) or absence of oxygen (anaerobic).

8. Aerobic Respiration
Most eukaryotes and many prokaryotes will continue to break down pyruvate using oxygen a final oxidizing agent
Other organisms (or in different conditions), pyruvate can be metabolised without oxygen, using anaerobic pathways.

9. Glycolysis Overview
Pyruvate is not the only product of glycolysis, and to see what else is produced (and ultimately how energy is produced) we need to look in more detail.
Note the net reaction in the bottom of the diagram.

10. Energy Investment
Glucose is insufficiently reactive and must be phosphorylated and isomerized to become more reactive. Like in all steps of glycolysis, enzymes are used to facilitate these reactions.
The phosphates come from ATP.
In the last step shown here, DHAP is converted to G3P, and the result is two molecules of G3P.

11. Energy Return
The next five reactions occur twice, once for each G3P produced previously. These reactions release energy from the G3P molecules and convert it to Pyruvate.
Energy is captured in the form of ATP (4 produced here) and the reduction of two NAD+ into NADH. As two ATP are used in the energy investment phase, this results in a net of 2 ATP.
Net energy molecules per glucose: 2 ATP, 2 NADH

12. Substrate Level Phosphorylation
In photosynthesis we learned about how ATP could be generated through the process of photophosphorylation – this isn’t the only way that ATP can be created, as you’re now seeing.
Some enzymes, called kinases, can transfer phosphates from high energy donor molecules to recipient substrates (like ADP!)
This is given the name substrate level phosphorylation.

13. What Do I Need to Know?
by no means do you need to memorize or learn all the names and steps.
follow the carbons and the energy (know where energy is captured and where waste is produced).
read page 98 of textbook for a detailed description
learn and love the finger dance!

14. Review Why is glycolysis considered an anaerobic pathway?
Write out the net reaction of glycolysis including all reactants and products.
Some organisms can survive through glycolysis alone, what conclusions can you make about them?
How are molecules like amino acids and triglycerides related to the process of glycolysis?
What makes glucose so special as a starting point for this pathway?