Summary Topic 2: Biological molecules

Biological Molecules
Oxidation and reduction reactions
- Loss of electrons  oxidation  formation of positive ion
- Receiving of election  reduction  formation of negative ion

Bonding and formation of molecules
- Covalent bonding: atoms share a pair of electrons in their outer shell  the outer
shell of both atoms is filled, and a stable molecule is formed
- Ionic bonding: ions with opposite charges attract one another. Weaker than covalent
bonding
- Hydrogen bonding: weak attractive force occurs between the hydrogen of an
electronegative atom of one molecule and an electronegative atom of another
molecule

, Protons Neutrons Electrons
(no charge) (-ve)
(+ve)




Isotopes Atom Ion


Inorganic mineral
Molecules
ions




Nucleotides Monosaccharides Fatty acids Glycerol Amino acids Water


Lipids
Polynucleotides Polysaccharides Polypeptides
(nucleic acid) (carbohydrates) (proteins)




® Condensation
® Hydrolysis

, Carbohydrates
Monosaccharides
 Sweet tasting
 Soluble
 Same number Carbon and Oxygen atoms but twice as many Hydrogen atoms
 (CH2O)n ® n = 3 to 7

Types of monosaccharides
Formula Name Examples
C3O6H3 Triose Glyceraldehyde
C5H10O5 Pentose Ribose
Deoxyribose
C6H12O6 Hexose Glucose
Fructose
Galactose

*All are reducing sugars = all will test positive when tested with Benedict’s solution




a-glucose  hydroxyl
group is at the bottom




b-glucose  hydroxyl group is at
the top