3. Introduction
• Water is the most abundant
substance in cells (70% of a cells
weight)
• With the exception of water nearly all
the molecules inside cells are based
on carbon
4. Introduction
• 92 naturally occurring elements
• Living organisms made of only a
small proportion of these elements
• Carbon, hydrogen , nitrogen and
oxygen make up 96.5% of an
organisms weight
5.
6. Properties of Carbon
• Capable of forming very large
molecules
• Can form 4 covalent bonds with
other atoms
• Can join to each other to form rings
and chains
7. C-C compounds
C C Saturated chains
C C Unsaturated chains
Rings
N
N
8. Common Chemical Groups
• Certain combinations of atoms (chemical
groups) repeatedly occur in biomolecules
e.g. -CH3 (methyl), -COOH (carboxyl),
-C= O (carbonyl)
• Other common chemical groups include
-NH2 (amino) and -PO3
2- (phosphate)
• These groups influence the chemical and
physical properties of biomolecules
9. Biomolecules
• There are four major classes of small
organic molecules in cells i.e. Amino
acids, nucleotides, sugars and fatty acids
• Some of these can be used as monomer
subunits to assemble large
macromolecules i.e. proteins , nucleic
acids and carbohydrates
• Fatty acids can also be assembled into
fats and lipids
12. Building blocks: amino acids
• Building blocks of proteins
• 20 different types of amino acids
• Amino acids can be charged or uncharged
• Uncharged amino acids can be polar or
non-polar
• Amino acid composition influences
protein structure and function
14. Building blocks: nucleotides
• Consist of a nitrogen containing ring
structure connected to a 5C sugar
• The sugar can be ribose or deoxyribose
• One or more phosphate groups are
attached
• Nucleotides are the building blocks of
DNA and RNA
• Nucleotides also act as short term carriers
of cellular energy (ATP)
17. Building Blocks: sugars
• Monosaccharide= monomer
• Important energy source
• Can be assembled into
oligosaccharides and
polysaccharides
• Small oligosaccharides can
covalently link to proteins
(glycoproteins) and lipids
(glycolipids)
19. Building Blocks: fatty acids
• Can be saturated or unsaturated
• Contain hydrophobic hydrocarbon chains
and a hydrophilic carboxyl group
• Important energy reserve
• Stored as triacylglycerols (through ester
link to glycerol)
• Important component of cell membranes
(phospholipids)
21. Assembly of
Macromolecules
• Macromolecules are composed of
linear chains of monomer subunits
• Subunits are added by enzyme
controlled condensation reactions
• Biological function of
macromolecules is determined by
the sequence of subunits
