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12. Energy and Respiration
12.1 - Introduction to respiration
1. The role of respiration in synthesising ATP
2. Aerobic and anaerobic respiration
3. The four stages of aerobic respiration
The role of respiration in synthesising ATP
ATP = universal energy currency
ATP = Pi + ADP
Formation of ATP requires energy released in respiration - an example of an
anabolic reaction (a chemical reaction where small molecules are built up
into larger ones, using an input of energy)
Cells must continuously regenerate ATP during respiration through:
1. Substrate level phosphorylation - Direct transfer of a phosphate group
from a donor molecule to ADP
2. Chemiosmosis - Using the movement of protons across a membrane to
drive ATP synthesis
Substrate-level phosphorylation is an example of a substrate-linked reaction.
This is when ATP is made using energy provided directly by another chemical
12. Energy and Respiration 1
, reaction
Aerobic and anaerobic respiration
Respiration is the enzymatic release of energy from organic compounds in
living cells. The energy stored in ATP, which is the primary energy carrier in all
living cells, is originally derived from the sun.
Through photosynthesis, plants and other photosynthetic organisms convert
light energy into chemical energy stored in organic molecules. These molecules
are then used in respiration to generate ATP.
There are two types of cellular respiration
1. Aerobic respiration - this requires oxygen
2. Anaerobic respiration - this does not require oxygen
The four stages of aerobic cellular respiration
Human ATP production primarily occurs through glucose metabolism in aerobic
cellular respiration
Aerobic cellular respiration has four distinct stages.
Stage Location Main process Main products
Per glucose
Breakdown of glucose
molecule: 2 ATP, 2
1. Glycolysis cytoplasm into pyruvate
reduced NAD, 2
molecules
pyruvate
12. Energy and Respiration 2
, per pyruvate
Mitochondrial conversion of pyruvate molecule: 1 acetyl
2. The link reaction
matrix into acetyl CoA CoA, 1 reduced NAD,
1 CO_2_
Per acetyl CoA
Series of reactions molecule: 1 ATP, 3
mitochondrial
3. The krebs cycle starting with acetyl reduced NAD, 1
matrix
CoA reduced FAD, 2
CO_2_
transfer of electrons
4. Oxidative
Inner through proteins,
phosphorylation approximately 30
mitochondrial creating a proton
(electron transport ATP, water
membrane gradient that allows the
chain)
synthesis of ATP
While glucose is the primary fuel, other respiratory substrate such as fatty
acids and amino acids can also be used in respiration. Oxygen is essential for
aerobic respiration. This is why breathing is vital, as it supplies oxygen for ATP
synthesis.
12.2 - Glycolysis
1. Where glycolysis occurs
2. The main steps in glycolysis
3. The reactants and products of glycolysis
Introduction to glycolysis
Glycolysis is the first stage of aerobic respiration. It occurs in the cytoplasm of
cells.
It breaks glucose, a six-carbon molecule, into two three-carbon pyruvate
molecules. This happens through a series of reactions involving specific
enzymes.
Glycolysis does not require oxygen so it is an anaerobic process. As well as
pyruvate, glycolysis also produces small amounts of ATP and an electron
carrier called reduced NAD (NADH).
Reactants and products of glycolysis
The reactants required for glycolysis are:
one glucose molecule
12. Energy and Respiration 3
12. Energy and Respiration
12.1 - Introduction to respiration
1. The role of respiration in synthesising ATP
2. Aerobic and anaerobic respiration
3. The four stages of aerobic respiration
The role of respiration in synthesising ATP
ATP = universal energy currency
ATP = Pi + ADP
Formation of ATP requires energy released in respiration - an example of an
anabolic reaction (a chemical reaction where small molecules are built up
into larger ones, using an input of energy)
Cells must continuously regenerate ATP during respiration through:
1. Substrate level phosphorylation - Direct transfer of a phosphate group
from a donor molecule to ADP
2. Chemiosmosis - Using the movement of protons across a membrane to
drive ATP synthesis
Substrate-level phosphorylation is an example of a substrate-linked reaction.
This is when ATP is made using energy provided directly by another chemical
12. Energy and Respiration 1
, reaction
Aerobic and anaerobic respiration
Respiration is the enzymatic release of energy from organic compounds in
living cells. The energy stored in ATP, which is the primary energy carrier in all
living cells, is originally derived from the sun.
Through photosynthesis, plants and other photosynthetic organisms convert
light energy into chemical energy stored in organic molecules. These molecules
are then used in respiration to generate ATP.
There are two types of cellular respiration
1. Aerobic respiration - this requires oxygen
2. Anaerobic respiration - this does not require oxygen
The four stages of aerobic cellular respiration
Human ATP production primarily occurs through glucose metabolism in aerobic
cellular respiration
Aerobic cellular respiration has four distinct stages.
Stage Location Main process Main products
Per glucose
Breakdown of glucose
molecule: 2 ATP, 2
1. Glycolysis cytoplasm into pyruvate
reduced NAD, 2
molecules
pyruvate
12. Energy and Respiration 2
, per pyruvate
Mitochondrial conversion of pyruvate molecule: 1 acetyl
2. The link reaction
matrix into acetyl CoA CoA, 1 reduced NAD,
1 CO_2_
Per acetyl CoA
Series of reactions molecule: 1 ATP, 3
mitochondrial
3. The krebs cycle starting with acetyl reduced NAD, 1
matrix
CoA reduced FAD, 2
CO_2_
transfer of electrons
4. Oxidative
Inner through proteins,
phosphorylation approximately 30
mitochondrial creating a proton
(electron transport ATP, water
membrane gradient that allows the
chain)
synthesis of ATP
While glucose is the primary fuel, other respiratory substrate such as fatty
acids and amino acids can also be used in respiration. Oxygen is essential for
aerobic respiration. This is why breathing is vital, as it supplies oxygen for ATP
synthesis.
12.2 - Glycolysis
1. Where glycolysis occurs
2. The main steps in glycolysis
3. The reactants and products of glycolysis
Introduction to glycolysis
Glycolysis is the first stage of aerobic respiration. It occurs in the cytoplasm of
cells.
It breaks glucose, a six-carbon molecule, into two three-carbon pyruvate
molecules. This happens through a series of reactions involving specific
enzymes.
Glycolysis does not require oxygen so it is an anaerobic process. As well as
pyruvate, glycolysis also produces small amounts of ATP and an electron
carrier called reduced NAD (NADH).
Reactants and products of glycolysis
The reactants required for glycolysis are:
one glucose molecule
12. Energy and Respiration 3
