molecules of life.pptx

1. Molecules of life
• Organisms are composed of matter, which is any
thing that takes up space and has mass
• Matter is made up of elements, elements cannot be
broken down further by chemical reactions
• Just four elements C, H, O and N make up
approximately 96% of living matter
• Of all the chemical elements, carbon is unparalleled
in its ability to form molecules that are large,
complex and varied
• Most bio-molecules can be regarded as derivative of
hydrocarbons, with hydrogen atoms replaced by a
variety of functional groups

2. Molecules of life
• The properties of an organic molecule depend on
the arrangement of its carbon skeleton and on
the functional group attached to the skeleton

3. Molecules of life
• Cells contains a universal set of molecules dissolved in
the cytosol
• This collection of molecules includes the common amino
acids, nucleotides, sugars and carboxylic acids
• The universal occurrence of the same set of compounds
in living cells reflects the common evolutionary origin of
all life forms.
• Large macromolecules like carbohydrates, protein and
nucleic acids are polymers built from these smaller
molecules called monomers
• A polymer is a long molecule consisting of many similar
or identical building blocks linked by covalent bond

4. Carbohydrates
• Carbohydrates serve as fuel and building
material
• Carbohydrate include sugars and polymers of
sugars
• Simplest carbohydrates are monosaccharide
• Disaccharides are double sugars, consisting of
two monosaccharides joined by a glycosidic
linkage e.g. – Maltose, lactose, Sucrose
• Carbohydrate macromolecules are polymer
called polysaccharide, composed of many
sugar building block e.g. – Starch, Cellulose

5. Sugars
• Sugars have a general formula of CH2O
• Trademark of a sugar molecule is presence of one
carbonyl group and multiple hydroxyl group
• Depending on the location of the carbonyl group
a sugar, a sugar is either an aldose or a ketose
• Sugars vary in the size of their carbon skeleton
e.g. – triose, pentose, hexose etc.
• Sugars also vary in the way their parts are
arranged spatially around asymmetric carbons
• In aqueous solution most of the five and six
carbon sugars, form rings to gain stability

7. Linear and ring forms of glucose