AS Biology Unit F212: Molecules, Biodiversity,
Food and Health
Module 1: Biological Membranes
Topic 1: Biological Membranes
● Biological molecules grouped according to chemical properties, made of C, H, O, N ( some
have P and S)
● Single small molecules (monomers) -> join to make polymers
● Carbohydrates: monosaccharide – polysaccharide
● Proteins: amino acids – polypeptides/proteins
● Nucleic acids: nucleotides – DNA/RNA
● Lipids: don’t form monomers, are in components but have largest unit i.e. triglyceride
Carbon:
● Framework atom, forms basis of all biological molecules
● Forms long chains and rings – forms dif molecules w/ dif structures and properties
● Forms covalent bonds – electrons shared between atoms to form new molecules, v strong as
full outer shells
Condensation - Chemical reaction that links biological monomers together to form polymers
by the formation of new bonds and releasing water (anabolic)
● Water molecule released
● Covalent bond formed
● Larger molecule formed by bonding of smaller molecule
Hydrolysis - Chemical reaction that splits larger molecules into smaller molecules by splitting
bonds w/ the addition of water (catabolic)
● Water molecule added
● Covalent bond broken
● Smaller molecule formed by splitting of larger molecule
Carbohydrates:
● 10% organic matter in a cell
● Group of molecules containing C, H, O in ratio C n(H2O)n
● Energy source – released from glucose in resp.
● Energy store – starch (plants) glycogen (animals)
● Structural molecule – cellulose
● Some form larger molecules – nucleotides/glycolipids
● 3 main groups of carbohydrates: monosaccharides/single sugars (glucose, fructose,
galactose), disaccharides/double sugars (sucrose, maltose, lactose), polysaccharides/many
sugars (starch, glycogen, cellulose)
● Monosaccharides = sweet, soluble, form crystals (properties of all mono/di)
● Cn(H2O)n
● Grouped according to no. of carbons in molecule: Triose (3-membered ring), Pentose (5-
membered ring), Hexose (6-membered ring)
● Differences: α-glucose OH group on C1 BELOW, β-glucose OH group on C1 ABOVE = this
changes overall shape = dif properties
● Isomers = dif forms of same molecule
, Formation and breaking down a disaccharide
α-glucose + α-glucose -> maltose +water maltose +water -> α-glucose + α-glucose
C6H12O6 + C6H12O6 -> C12H22O11 + H2O C12H22O11 + H2O -> C6H12O6 + C6H12O6
Glucose - Energy and structure:
● resp. = breaking down glucose = release energy needed to make ATP
● Glucose + Oxygen -> Carbon Dioxide + Water + Energy
- Breaking down glucose and using it in resp:
● series of steps catalysed by specific enzymes
● carbohydrate molecules = dif shapes
● active site and substrate must be complimentary
● so that substrate will fit/lock and key hypothesis
● Animals and plants – only break down α-glucose
● Enzyme function based on shape
● Don’t have enzyme to break down β-glucose which has dif arrangement of –H and –OH
● Bacteria does have enzyme to break down β-glucose
Relating structure to function
● Soluble: easily transported around organism
● Small: transported/diffuse across membrane quick
● Easily/quickly respired: to form ATP
● Molecules can join: to make di/polysaccharides
Carbohydrate polymers – energy storage
● Amylose – condensation reaction of thousands of glucose
Food and Health
Module 1: Biological Membranes
Topic 1: Biological Membranes
● Biological molecules grouped according to chemical properties, made of C, H, O, N ( some
have P and S)
● Single small molecules (monomers) -> join to make polymers
● Carbohydrates: monosaccharide – polysaccharide
● Proteins: amino acids – polypeptides/proteins
● Nucleic acids: nucleotides – DNA/RNA
● Lipids: don’t form monomers, are in components but have largest unit i.e. triglyceride
Carbon:
● Framework atom, forms basis of all biological molecules
● Forms long chains and rings – forms dif molecules w/ dif structures and properties
● Forms covalent bonds – electrons shared between atoms to form new molecules, v strong as
full outer shells
Condensation - Chemical reaction that links biological monomers together to form polymers
by the formation of new bonds and releasing water (anabolic)
● Water molecule released
● Covalent bond formed
● Larger molecule formed by bonding of smaller molecule
Hydrolysis - Chemical reaction that splits larger molecules into smaller molecules by splitting
bonds w/ the addition of water (catabolic)
● Water molecule added
● Covalent bond broken
● Smaller molecule formed by splitting of larger molecule
Carbohydrates:
● 10% organic matter in a cell
● Group of molecules containing C, H, O in ratio C n(H2O)n
● Energy source – released from glucose in resp.
● Energy store – starch (plants) glycogen (animals)
● Structural molecule – cellulose
● Some form larger molecules – nucleotides/glycolipids
● 3 main groups of carbohydrates: monosaccharides/single sugars (glucose, fructose,
galactose), disaccharides/double sugars (sucrose, maltose, lactose), polysaccharides/many
sugars (starch, glycogen, cellulose)
● Monosaccharides = sweet, soluble, form crystals (properties of all mono/di)
● Cn(H2O)n
● Grouped according to no. of carbons in molecule: Triose (3-membered ring), Pentose (5-
membered ring), Hexose (6-membered ring)
● Differences: α-glucose OH group on C1 BELOW, β-glucose OH group on C1 ABOVE = this
changes overall shape = dif properties
● Isomers = dif forms of same molecule
, Formation and breaking down a disaccharide
α-glucose + α-glucose -> maltose +water maltose +water -> α-glucose + α-glucose
C6H12O6 + C6H12O6 -> C12H22O11 + H2O C12H22O11 + H2O -> C6H12O6 + C6H12O6
Glucose - Energy and structure:
● resp. = breaking down glucose = release energy needed to make ATP
● Glucose + Oxygen -> Carbon Dioxide + Water + Energy
- Breaking down glucose and using it in resp:
● series of steps catalysed by specific enzymes
● carbohydrate molecules = dif shapes
● active site and substrate must be complimentary
● so that substrate will fit/lock and key hypothesis
● Animals and plants – only break down α-glucose
● Enzyme function based on shape
● Don’t have enzyme to break down β-glucose which has dif arrangement of –H and –OH
● Bacteria does have enzyme to break down β-glucose
Relating structure to function
● Soluble: easily transported around organism
● Small: transported/diffuse across membrane quick
● Easily/quickly respired: to form ATP
● Molecules can join: to make di/polysaccharides
Carbohydrate polymers – energy storage
● Amylose – condensation reaction of thousands of glucose
