Chapter 12: Energy and Respiration
All living organisms need a continuous supply of energy to maintain their metabolism. They
either absorb light energy (autotrophs) or chemical potential energy (heterotrophs). This is to do
the work necessary to live.
Work includes:
1) anabolic reactions (anabolic reactions - synthesis of complex substances from simpler ones)
2) active transport (transport of substances against concentration gradient)
3) movement e.g., muscle contraction, cilia movement, locomotion
4) bioluminescence, electrical discharge, temperature regulation, etc.
ATP
ATP acts as a universal energy currency, providing the energy required for various
cellular processes. ATP is made when Pi is combined with ADP, using energy released
in respiration.
The formation of ATP is an example of an anabolic reaction. This is a chemical reaction
in which 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 reaction.
, Features of ATP that make it suitable as the universal energy currency
1) small
2) water-soluble
3) easily transported around the cell
4) easily hydrolysed to release energy
5) relatively large quantity of energy released ATP + H2O ⇌ ADP + Pi (inorganic phosphate) 6)
rapid turnover rate
7) readily available in cells upon demand as stores are released in manageable amounts,
meaning no energy is wasted
Synthesis of ATP (Respiration)
ATP is synthesised in substrate-linked reactions in glycolysis and in the Krebs cycle.
1) The process by which ATP is synthesised is called chemiosmosis.
2) It occurs in the inner mitochondrial membrane (or the thylakoid membrane of a chloroplast).
Structure of ATP
All living organisms need a continuous supply of energy to maintain their metabolism. They
either absorb light energy (autotrophs) or chemical potential energy (heterotrophs). This is to do
the work necessary to live.
Work includes:
1) anabolic reactions (anabolic reactions - synthesis of complex substances from simpler ones)
2) active transport (transport of substances against concentration gradient)
3) movement e.g., muscle contraction, cilia movement, locomotion
4) bioluminescence, electrical discharge, temperature regulation, etc.
ATP
ATP acts as a universal energy currency, providing the energy required for various
cellular processes. ATP is made when Pi is combined with ADP, using energy released
in respiration.
The formation of ATP is an example of an anabolic reaction. This is a chemical reaction
in which 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 reaction.
, Features of ATP that make it suitable as the universal energy currency
1) small
2) water-soluble
3) easily transported around the cell
4) easily hydrolysed to release energy
5) relatively large quantity of energy released ATP + H2O ⇌ ADP + Pi (inorganic phosphate) 6)
rapid turnover rate
7) readily available in cells upon demand as stores are released in manageable amounts,
meaning no energy is wasted
Synthesis of ATP (Respiration)
ATP is synthesised in substrate-linked reactions in glycolysis and in the Krebs cycle.
1) The process by which ATP is synthesised is called chemiosmosis.
2) It occurs in the inner mitochondrial membrane (or the thylakoid membrane of a chloroplast).
Structure of ATP
