Download - General biochemistry
BIOCHEMISTRY
Chemistry of life
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
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
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
C-C compounds
C C Saturated chains
Rings
Unsaturated chains
CC
N
N
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
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
Chemical Composition of the cell
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
Amino acids
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)
Nucleotides
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)
Monosaccharides
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)
Fatty acids
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
Assembly of Macromolecules
Monosaccharides