Respiration
Glycolysis
- Takes place in the cytoplasm
- Glucose is converted into glucose phosphate using two molecules of ATP; we can say
glucose has been phosphorylated using the phosphate from ATP.
- The glucose phosphate is split into two molecules of triose phosphate (TP) each TP
contains 3 carbon atoms.
- Each TP is the oxidated to form pyruvate. Each pyruvate contains 3 carbon atoms
- A Hydrogen is removed from each pyruvate molecule and transferred to a carrier
molecule called NAD forming reduced NAD.
- Two molecules of ATP are produced per molecule of pyruvate.
- The pyruvate molecules are now small enough to pass by active transport into the
mitochondria.
The link reaction
- Takes place in the mitochondria membrane (in the matrix)
- Pyruvate is oxidized to form acetate
- The 3-carbon pyruvate loses a carbon dioxide molecule and 2 hydrogens.
- The hydrogens are accepted by NAD to form reduced NAD.
- The 2-carbon acetate combines with coenzyme A to form acetyl coenzyme A.
- The overall equation can be summarized by :
Pyruvate + NAD + CoA acetyl CoA + reduced NAD + CO2
, The Krebs cycle
- Takes place in the mitochondria membrane (in the matrix)
- The 2-carbon acetyl coenzyme A combines with a 4-carbon molecule to form a 6-
carbon molecule
- In a series of oxidation reduction reactions the 6-carbon molecule is eventually
broken down to a 2-carbon molecule and a 4-carbon molecule, the 4-carbon
molecule can then combine with another molecule of acetyl coenzyme A.
- One molecule of ATP is produced along with reduced NAD and reduced FAD
(reduced as hydrogen is lost when the 6-carbon molecule is broken down) and 2
molecules of carbon dioxide are lost.
- The production of ATP this way is called substrate level phosphorylation.
- As 2 pyruvate molecules are produced for each original glucose molecule, the yield
from a single glucose molecule is double the quantities above e.g. 2 ATP molecules
are produced
Oxidative phosphorylation
- Takes place in the cristae
- The reduced NAD and reduced FAD donate their electrons to the first molecule in
the electron transport chain.
- The electrons pass along a series of electron carriers in a series of oxidation
reduction reactions.
- The energy the electrons release is used to transport protons from the matrix into
the inner membrane space.
- The protons diffuse back into the matrix via ATP synthase generating ATP from ADP
and an inorganic phosphate.
- At the end of the chain the electrons combine with the protons and oxygen to form
water, oxygen is therefore the final electron acceptor in the electron transport chain.
Glycolysis
- Takes place in the cytoplasm
- Glucose is converted into glucose phosphate using two molecules of ATP; we can say
glucose has been phosphorylated using the phosphate from ATP.
- The glucose phosphate is split into two molecules of triose phosphate (TP) each TP
contains 3 carbon atoms.
- Each TP is the oxidated to form pyruvate. Each pyruvate contains 3 carbon atoms
- A Hydrogen is removed from each pyruvate molecule and transferred to a carrier
molecule called NAD forming reduced NAD.
- Two molecules of ATP are produced per molecule of pyruvate.
- The pyruvate molecules are now small enough to pass by active transport into the
mitochondria.
The link reaction
- Takes place in the mitochondria membrane (in the matrix)
- Pyruvate is oxidized to form acetate
- The 3-carbon pyruvate loses a carbon dioxide molecule and 2 hydrogens.
- The hydrogens are accepted by NAD to form reduced NAD.
- The 2-carbon acetate combines with coenzyme A to form acetyl coenzyme A.
- The overall equation can be summarized by :
Pyruvate + NAD + CoA acetyl CoA + reduced NAD + CO2
, The Krebs cycle
- Takes place in the mitochondria membrane (in the matrix)
- The 2-carbon acetyl coenzyme A combines with a 4-carbon molecule to form a 6-
carbon molecule
- In a series of oxidation reduction reactions the 6-carbon molecule is eventually
broken down to a 2-carbon molecule and a 4-carbon molecule, the 4-carbon
molecule can then combine with another molecule of acetyl coenzyme A.
- One molecule of ATP is produced along with reduced NAD and reduced FAD
(reduced as hydrogen is lost when the 6-carbon molecule is broken down) and 2
molecules of carbon dioxide are lost.
- The production of ATP this way is called substrate level phosphorylation.
- As 2 pyruvate molecules are produced for each original glucose molecule, the yield
from a single glucose molecule is double the quantities above e.g. 2 ATP molecules
are produced
Oxidative phosphorylation
- Takes place in the cristae
- The reduced NAD and reduced FAD donate their electrons to the first molecule in
the electron transport chain.
- The electrons pass along a series of electron carriers in a series of oxidation
reduction reactions.
- The energy the electrons release is used to transport protons from the matrix into
the inner membrane space.
- The protons diffuse back into the matrix via ATP synthase generating ATP from ADP
and an inorganic phosphate.
- At the end of the chain the electrons combine with the protons and oxygen to form
water, oxygen is therefore the final electron acceptor in the electron transport chain.
