Molecule of water = 1 atom of Oxygen joined to 2 atoms of Hydrogen by shared electrons
1. Because shared negative hydrogen electrons are pulled towards the oxygen atom,
the other side of each hydrogen atom is left with a slight positive charge
2. The unshared negative electrons on the oxygen atom give it a slight negative
charge - makes water a polar molecule (has 𝛿− charge on one side and 𝛿+ on
the other)
3. Slightly negatively-charged oxygen atoms attract the slightly positively-charged
hydrogen atoms of other water molecules
4. This is Hydrogen Bonding (weak intermolecular bonds)
Structure related to its properties and functions:
● Hydrogen bonds give water a high specific heat capacity (energy required to
raise the temp of 1 gram of a substance by 1°C)
○ Hydrogen bonds absorb a lot of energy - so high SHC
○ So water doesn’t experience rapid temp changes - good habitat
● Hydrogen bonds give water a high latent heat of evaporation
○ A lot of energy needed to break hydrogen bonds between H2O molecules
○ Useful for living organisms - water’s good for cooling things (sweat
when too hot - cools surface of skin)
● Water’s polarity makes it very cohesive (attraction between molecules of same
type)
○ Very cohesive because they’re polar
○ Helps water to flow (good for transporting substances)
● Water’s polarity makes it a good solvent
○ Water = polar so slightly positive end will be attracted to negative ion
(and the same for the other one)
○ Ions get surrounded = they dissolve
○ Important ions can dissolve in water in blood and then transported
● Ice = Less dense
○ Water molecules held further apart - each water molecule forms 4
hydrogen bonds to other water molecules, making a lattice shape
○ Forms insulating layer on top of water (fishes don’t freeze/still move
around)
Monomers = individual molecules that make up a polymer
Polymer = molecule made from monomers bonded together
Carbohydrates: First important biological molecule
● Monomers that make this are called monosaccharides
○ Example: Glucose: Monosaccharide with 6 carbon atoms (hexose)
○ 2 forms: alpha and beta
○ It’s structure is related to its function as the main energy source in animals
+ plants - structure makes it soluble - easily transported
, Example: Ribose: Monosaccharide with 5 carbon atoms
(pentose)
All carbohydrates made up of the same 3 chemical
elements: Carbon, Hydrogen, Oxygen
For every carbon atom = 2 hydrogen atoms and 1 oxygen
atom
Monosaccharides are joined together by glycosidic bonds
During synthesis, a hydrogen atom on one monosaccharide bonds to a hydroxyl (OH)
group on the other, releasing a water molecule = Condensation reaction
Hydrolysis = water molecule reacts with glycosidic bond, breaking it apart
When 2 monosaccharides join together = disaccharide
Example:
● 2 alpha glucose molecules are joined together by a glycosidic bond to form
maltose
● Alpha glucose and fructose joined together = sucrose
● Beta glucose and galactose = lactose
When more than 2 monosaccharides join together = polysaccharides
Example: Lots of alpha glucose molecules are joined together by glycosidic bonds to
form amylose
1. Because shared negative hydrogen electrons are pulled towards the oxygen atom,
the other side of each hydrogen atom is left with a slight positive charge
2. The unshared negative electrons on the oxygen atom give it a slight negative
charge - makes water a polar molecule (has 𝛿− charge on one side and 𝛿+ on
the other)
3. Slightly negatively-charged oxygen atoms attract the slightly positively-charged
hydrogen atoms of other water molecules
4. This is Hydrogen Bonding (weak intermolecular bonds)
Structure related to its properties and functions:
● Hydrogen bonds give water a high specific heat capacity (energy required to
raise the temp of 1 gram of a substance by 1°C)
○ Hydrogen bonds absorb a lot of energy - so high SHC
○ So water doesn’t experience rapid temp changes - good habitat
● Hydrogen bonds give water a high latent heat of evaporation
○ A lot of energy needed to break hydrogen bonds between H2O molecules
○ Useful for living organisms - water’s good for cooling things (sweat
when too hot - cools surface of skin)
● Water’s polarity makes it very cohesive (attraction between molecules of same
type)
○ Very cohesive because they’re polar
○ Helps water to flow (good for transporting substances)
● Water’s polarity makes it a good solvent
○ Water = polar so slightly positive end will be attracted to negative ion
(and the same for the other one)
○ Ions get surrounded = they dissolve
○ Important ions can dissolve in water in blood and then transported
● Ice = Less dense
○ Water molecules held further apart - each water molecule forms 4
hydrogen bonds to other water molecules, making a lattice shape
○ Forms insulating layer on top of water (fishes don’t freeze/still move
around)
Monomers = individual molecules that make up a polymer
Polymer = molecule made from monomers bonded together
Carbohydrates: First important biological molecule
● Monomers that make this are called monosaccharides
○ Example: Glucose: Monosaccharide with 6 carbon atoms (hexose)
○ 2 forms: alpha and beta
○ It’s structure is related to its function as the main energy source in animals
+ plants - structure makes it soluble - easily transported
, Example: Ribose: Monosaccharide with 5 carbon atoms
(pentose)
All carbohydrates made up of the same 3 chemical
elements: Carbon, Hydrogen, Oxygen
For every carbon atom = 2 hydrogen atoms and 1 oxygen
atom
Monosaccharides are joined together by glycosidic bonds
During synthesis, a hydrogen atom on one monosaccharide bonds to a hydroxyl (OH)
group on the other, releasing a water molecule = Condensation reaction
Hydrolysis = water molecule reacts with glycosidic bond, breaking it apart
When 2 monosaccharides join together = disaccharide
Example:
● 2 alpha glucose molecules are joined together by a glycosidic bond to form
maltose
● Alpha glucose and fructose joined together = sucrose
● Beta glucose and galactose = lactose
When more than 2 monosaccharides join together = polysaccharides
Example: Lots of alpha glucose molecules are joined together by glycosidic bonds to
form amylose
