Post on 03-Nov-2014
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Glycolysis
The first stage of respiration
Glycolysis
Respiration
• Process of respiration is split into four parts
• By breaking it into four parts we will have less to learn at any one stage
Glycolysis is the first stage of respiration!
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate
Glucose is a hexose (6-carbon) molecule
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate
Glucose is a hexose (6-carbon) molecule
Pyruvate is a triose (3-carbon) molecule
Glycolysis is the first stage of respiration!
Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate
Glucose is a hexose (6-carbon) molecule
Pyruvate is a triose (3-carbon) molecule
Pyruvate is also known as pyruvic acid
• Glycolysis takes place in the cytoplasm of cells.
• Glycolysis takes place in the cytoplasm of cells.
• It’s the first stage of both aerobic and anaerobic respiration.
• It’s the first stage of both aerobic and anaerobic respiration.
•It doesn’t need oxygen to take place – so it’s anaerobic
• It’s the first stage of both aerobic and anaerobic respiration.
•It doesn’t need oxygen to take place – so it’s anaerobic
There are TWO STAGES of GLYCOLYSIS – Phosphorylation and Oxidation
Glycolysis
Glycolysis
1
2
A
B
Glycolysis
1
2
A
B
These arrows in diagrams just mean that A goes into the main reaction and is
converted to B.
A will normally release or collect something from
molecule 1, e.g. hydrogen or phosphate
Stage One - Phosphorylation
Stage One - Phosphorylation
1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.
Stage One - Phosphorylation
1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.
2.The hexose phosphate is split using water
Stage One - Phosphorylation
1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.
2.The hexose phosphate is split using water (hydrolysis)
Stage One - Phosphorylation
1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.
2.The hexose phosphate is split using water (hydrolysis)
3.2 molecules of triose phosphate and 2 molecules of ADP are created.
A triose phosphate is just a simple 3-carbon sugar with a phosphate group attached.
Different books use different names!
What’s the point?
• Glucose can now no longer leave the cell.
What’s the point?
• Glucose can now no longer leave the cell.
• Molecules produced are much more reactive!
Stage Two - Oxidation
Stage Two - Oxidation
1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.
Stage Two - Oxidation
1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.
2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)
Stage Two - Oxidation
1. The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.
2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)
A coenzyme is a helper molecule that carries chemical groups or ions, e.g. NAD+ removes H+ and carries it
to other molecules.
Stage Two - Oxidation
1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.
2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)
3. 4 ATP are produced, but 2 were used up at the beginning, so there’s a net gain of 2 ATP.
Next in Aerobic respiration….
Next in Aerobic respiration….
1. The 2 molecules of reduced NAD go to the electron transport chain (ETC), part 4 of respiration.
Next in Aerobic respiration….
1. The 2 molecules of reduced NAD go to the electron transport chain (ETC), part 4 of respiration.
2. The two pyruvate molecules go into the matrix of the mitochondria for the link reaction.
I bet your so excited you can not wait!
The Link Reaction
The Link Reaction
The second stage of respiration
You are now in the matrix of the mitochondria!
Link Reaction – 2nd stage of respiration
Link Reaction – 2nd stage of respiration
The Link Reaction converts Pyruvate to Acetyl Coenzyme A
Link Reaction – 2nd stage of respiration
The Link Reaction converts Pyruvate to Acetyl Coenzyme A
The link reaction happens when oxygen is available.
Link Reaction – 2nd stage of respiration
Link Reaction – 2nd stage of respiration
1. One carbon atom is removed from pyruvate in the form of CO2.
Link Reaction – 2nd stage of respiration
1. One carbon atom is removed from pyruvate in the form of CO2.
2. The remaining 2-carbon molecule combines with coenzyme A to produce acetyl coenzyme A (acetyl CoA).
Link Reaction – 2nd stage of respiration
1. One carbon atom is removed from pyruvate in the form of CO2.
2. The remaining 2-carbon molecule combines with coenzyme A to produce acetyl coenzyme A (acetyl CoA).
3. Another oxidation reaction happens when NAD+ collects more hydrogen ions. This forms reduced NAD (NADH + H+).
Link Reaction – 2nd stage of respiration
4. No ATP is produced in this reaction.
Link Reaction – 2nd stage of respiration
The Link reaction happens Twice for every Glucose Molecule
Link Reaction – 2nd stage of respiration
The Link reaction happens Twice for every Glucose Molecule
So for every glucose molecule used in glycolysis, two pyruvate and two acetyl CoA molecules are made.
So for each glucose molecule:
So for each glucose molecule:
•Two molecules of acetyl CoA go into Krebs cycle (part 3 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into Krebs cycle (part 3 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are released as a waste product of respiration
So for each glucose molecule:
•Two molecules of acetyl CoA go into Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are released as a waste product of respiration
•Two molecules of reduced NAD are formed and go into the electron transport chain (part 4 of respiration)
So for each glucose molecule:
•Two molecules of acetyl CoA go into Krebs cycle (part 3 of respiration)
•Two carbon dioxide molecules are released as a waste product of respiration
•Two molecules of reduced NAD are formed and go into the electron transport chain (part 4 of respiration)
Final thoughts….• Acetyl Co-what?????• It IS very confusing, but you need to know it.• Take your time and fet to grips with one stage at
a time.• Don’t worry if you can not remember all the
details straight away.• If you can remember where each stage starts
and what the products are, you’re getting there!