1.1 Introduction to biological molecules

What is covalent bonding?

Atoms share a pair of electrons in their outer shells

As a result the outer shells of both atoms is filled and a more stable compound, called a molecule, is formed

What is ionic bonding?

Ions with opposite charges attract one another

This electrostatic attraction is known as an ionic bond

Ionic bonds are weaker than covalent bonds

What is a polar molecule?

A molecule with an uneven distribution of charge is said to be polarised

What is hydrogen bonding?

The electrons within a molecule are not evenly distributed but tend to spend more time at one position

This region is more negatively charged than the rest of the molecule

The negative region of one polarised molecule and the positively charged region of another attract each other

A weak electrostatic bond is formed between the two

Although each bond is individually weak, they can collectively form important forces that alter the physical properties of molecules (especially true for water)

What are polymers and what is polymerisation?

Long chains of monomer sub-units are called polymers and the process by which they are formed is therefore called polymerisation

How are some polymers made?

Polythene and polyesters, are industrially produced

Polysaccharides, polypeptides and polynucleotides are made naturally by living organisms

What is the basic sub-unit of a polysaccharide?

Monosaccharide or single sugar, for example glucose

What are polynucleotides formed from?

Mononucleotide sub-units

What are polypeptides formed from?

By linking together peptides that have amino acids as their basic sub-unit

What is a condensation reaction?

Joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water

What is a hydrolysis reaction?

Breaks a chemical bond between two molecules and involves the use of water

Summary of atomic and molecular organisation

What is a metabolism?

All the chemical processes that take place collectively in living organisms

What does one mole contain?

The same number of particles as there are in 12g of carbon-12 atoms

12g of carbon-12 atoms contains 6.022×10²³ carbon atomsW

What is a molar solution (M)?

Solution that contains one mole of solute in each litre of solution

What is a mole?

Molecular mass (molecular weight) expressed as grams (= one gram molecular mass)

E.g. to make a molar solution of sodium chloride we must first find its molecular mass