Biological Molecules

Hydrogen bonds

Form between positive (+) and negative (-) molecules

Individually Weak

Continually breaking and reforming

Water is a dipolar molecule

Specific Heat Capacity

The heat energy that is needed to raise the temperature of 1kg of substance by 1^OC

Water has a lot of hydrogen bonds so lots of energy required to break those bonds so high specific heat capacity so can buffer temperature change

Aquatic Environment

Fairly constant temperature allowing aquatic organisms to survive

Ice is less dense than water

When water freezes the water molecules are pushed out

Importance of Ice floating on water

Animals can float on water

A body of water freezing over means the ice acts as an insulator during colder seasons for aquatic life such as fish

Latent Heat of Vaporisation

Energy required to turn water to gas

Importance:

Animals that sweat cool down as they use the heat energy of their body to evaporate the water off their surface

Plants are also cooled when water evaporates from their leaves

Water is cohesive

Means that water molecules tend to stick to each other due to hydrogen bonding between their polar molecules

Used for transpiration, allows small animals to live on the surface water of bodies

The many hydrogen bonds help hold water molecules together so they can flow in a continuous stream

Leads to surface tension making water behave as there is a skin

Water Adhesion

Water molecules stick to other surfaces or materials that are not water, due to intermolecular forces such as hydrogen bonding and electrostatic interactions

Water is a solvent

Things can dissolve in it

Important for reactions and dissolving positive and negative charges of water attracted to other molecules causing them to separate from each other and dissolve

Dissolved substances are free to move around and react with other molecules

Metabolite

Something involved in a metabolic reaction

Water molecules can also be involved in chemical reactions directly condensation and hydrolysis reactions

Hydrophillic

Can dissolve in water, substances attracted to water

Always polar molecules and ions

Hydrophobic

Insoluble in water

Non-polar

Inorganic Ions

Ion that doesn't contain Carbon or Hydrogen molecules

There are lots in the body that have a specific role

e.g. calcium, phosphate, potassium, hydrogen, iron, sodium ions

Hydrogen Ions

Protons

Concentration of H⁺ ions in a solution determines pH

More H⁺= Lower pH

Less H⁺= Higher pH

Iron Ions

2 types: Ferrous ions (Fe²⁺) and Ferric ions (Fe³⁺)

Bind oxygen

Haemoglobin is made up of 4 polypeptide chains that contain Fe²⁺

Sodium Ions

Required for the transport of glucose and amino acids across cell-surface membranes e.g. small intestine

Required for transmission of nerve impulses

Phosphate Ions

Attach to other molecules to form phosphate groups which are an essential component of DNA, RNA and ATP

Phosphates are also found in phospholipids, which are key components of the phospholipid bilayer of cell membranes

Calcium Ion

Activate ATP hydrolase, releasing energy that powers muscle contraction

4 main types of large biological molecules

Are called macromolecules which include:

Carbohydrates

Lipids

Proteins

Nucleic Acids

They are all made by joining smaller molecules together

Monomers

Small molecules that can join with another molecule to form larger molecules.

e.g. amino acids, glucose, fructose, galactose, ethane, nucleic acid

Monomer = 1 amino acid

Dipeptide = 2 amino acids

Monomers are formed by

Hydrolysis reaction

Polymers are formed by

Condensation reaction

Condensation

Release of water molecules in order to build up large molecules

Hydrolysis

Addition of a water molecule in order to break down large molecules

Polymer

A repeating chain of monomers bound together

Isomer

Same chemical formula but different arrangement of atom

Carbohydrate

CARBO HYDR ATE

carbon hydrogen oxygen

Monosaccharide

Monomers that make up carbohydrates e.g. glucose, galactose, fructose

No. of carbon atoms

Diose 2

Triose 3

Tetrose 4

Pentose 5

Hexose 6

Heptose 7

All monosaccharides

Can reduce Benedict's Reagent (which is reducing sugars)

Are sweet tasting

Are soluble

Are easily transported

Are the main respiratory substances

Alpha Glucose

C₆H₁₂O₆
Hexose
Energy source.
Component of starch and glycogen

Beta Glucose

C₆H₁₂O₆
Hexose