ENERGY AND RESPIRATION
1. Energy
1.1 Need for energy
Transporting substances across membranes - Active transport using the sodium-potassium pump in
cell membranes. Exocytosis of digested bacteria from white blood cells
Anabolic reactions - Synthesis of DNA from nucleotides. Synthesis of protein from amino acids
Movement - Cellular movement of chromosomes via the spindle. Contractions of muscles
Maintaining body temperature – Vasoconstriction and vasodilation in mammals and birds
Source of energy - photosynthesis and respiration
glucose + oxygen → carbon dioxide + water + energy
C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ
1.2 ATP – Universal energy currency
ATP is phosphorylated nucleotide, made up of:
o Ribose sugar
o Adenine base
o Three phosphate groups
Energy released during the reactions of respiration is
transferred to the molecule adenosine
triphosphate (ATP) – occurs in mitochondria
The benefits of using ATP as energy source:
The hydrolysis of ATP occurs quickly anywhere by enzymes - ATPase
ATP is stable at cellular pH levels
Small and soluble
Can be recycled – Broken down and formed again
, Hydrolysis of ATP
When ATP is hydrolysed (broken down) by water and the enzyme ATPase, ADP and inorganic
phosphate are produced
Synthesis of ATP
ATP is formed when ADP is combined with an inorganic phosphate (Pi) group
o This is an energy-requiring reaction
o Water is released as a waste product (ATP
synthesis is a condensation reaction)
Two types: Substrate-linked phosphorylation and Chemiosmosis
Substrate-linked phosphorylation Chemiosmosis
Process The phosphate of a substrate molecule is directly Hydrogen atom splits into electron and proton in matrix
transferred to ADP to form ATP.
High energy electrons are transferred to oxygen through
It uses energy directly provided by another chemical electron transport chain (made up of electron carriers)
reaction releasing energy that is used to pump protons
Proton (hydrogen ion) move against concentration
gradient from matrix to inner membrane. Then move
down concentration gradient into the matrix by
facilitated diffusion– releases energy
The energy is used by ATP synthase to synthesis ATP
Oxygen acts as the final hydrogen/electron acceptor to
form water
Location Cytoplasm of cells/ Matrix of mitochondria Inner mitochondrial membrane/ Thylakoid membrane
of chloroplasts
Quantity of ATP Small Large
Storage of ATP
Short term storage of ATP:
o Chemical stability of ATP highly reactive - breaks down releasing energy which is wasted
o Osmotic pressure of cell ATP is small and soluble – high concentration of ATP – water
potential increases – cell becomes turgid and bursts
1. Energy
1.1 Need for energy
Transporting substances across membranes - Active transport using the sodium-potassium pump in
cell membranes. Exocytosis of digested bacteria from white blood cells
Anabolic reactions - Synthesis of DNA from nucleotides. Synthesis of protein from amino acids
Movement - Cellular movement of chromosomes via the spindle. Contractions of muscles
Maintaining body temperature – Vasoconstriction and vasodilation in mammals and birds
Source of energy - photosynthesis and respiration
glucose + oxygen → carbon dioxide + water + energy
C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ
1.2 ATP – Universal energy currency
ATP is phosphorylated nucleotide, made up of:
o Ribose sugar
o Adenine base
o Three phosphate groups
Energy released during the reactions of respiration is
transferred to the molecule adenosine
triphosphate (ATP) – occurs in mitochondria
The benefits of using ATP as energy source:
The hydrolysis of ATP occurs quickly anywhere by enzymes - ATPase
ATP is stable at cellular pH levels
Small and soluble
Can be recycled – Broken down and formed again
, Hydrolysis of ATP
When ATP is hydrolysed (broken down) by water and the enzyme ATPase, ADP and inorganic
phosphate are produced
Synthesis of ATP
ATP is formed when ADP is combined with an inorganic phosphate (Pi) group
o This is an energy-requiring reaction
o Water is released as a waste product (ATP
synthesis is a condensation reaction)
Two types: Substrate-linked phosphorylation and Chemiosmosis
Substrate-linked phosphorylation Chemiosmosis
Process The phosphate of a substrate molecule is directly Hydrogen atom splits into electron and proton in matrix
transferred to ADP to form ATP.
High energy electrons are transferred to oxygen through
It uses energy directly provided by another chemical electron transport chain (made up of electron carriers)
reaction releasing energy that is used to pump protons
Proton (hydrogen ion) move against concentration
gradient from matrix to inner membrane. Then move
down concentration gradient into the matrix by
facilitated diffusion– releases energy
The energy is used by ATP synthase to synthesis ATP
Oxygen acts as the final hydrogen/electron acceptor to
form water
Location Cytoplasm of cells/ Matrix of mitochondria Inner mitochondrial membrane/ Thylakoid membrane
of chloroplasts
Quantity of ATP Small Large
Storage of ATP
Short term storage of ATP:
o Chemical stability of ATP highly reactive - breaks down releasing energy which is wasted
o Osmotic pressure of cell ATP is small and soluble – high concentration of ATP – water
potential increases – cell becomes turgid and bursts
