six carbon atoms are

only single bonds between the carbon atoms are known as saturated. • because it is saturated with hydrogens, e.g. stearic acid. • are one or more double bonds between carbons,. • fewer hydrogens the fatty acid is unsaturated,. • e.g. oleic acid.
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Plant Physiology - the study of how plants function - growth - plant behavior ( temperature, pressure, light) - complex synthetic process  ( photosynthesis, respiration)

Biological Molecules consist of a carbon backbone attached to functional groups determine  the characteristics, solubility chemical reactivity of the molecules.

Synthesizing Organic Molecules • Small molecules (e.g. amino acid ) are synthesize larger molecules (e.g. Protein). Amino acid add Amino acid Small molecule subunit /monomers

Protein larger molecules polymers

a. A typical organic molecule is composed of similar or identical subunits linked together. (e.g. starch)

A condensation reaction & Hydrolysis reaction

• Living organisms synthesize long organic molecules through condensation reactions, • a hydrogen removed from one subunit and a hydroxyl removed from a second subunit "condense" to form a molecule of water

• as the subunits are joined by a covalent bond • The reverse reaction, called hydrolysis, • uses water to break the molecule into individual subunits again.

The Principal Types of Biological Molecules all biological molecules fall into one of four categories : • carbohydrates • lipids • proteins • nucleic acids.

Carbohydrates All carbohydrates are  small water – soluble sugars (glucose, fructose) or  chains made by stringing sugar subunits together (starch, cellulose, glycogen).

 General Formula ---- ( CH2O)n Three Principle Kinds Monosaccharides Disaccharides Polysaccharides

•The general formula for carbohydrates is Cn(H2O)n.

Monosaccharides • consisting of one sugar molecule is a monosaccharide. • monosaccharide is glucose. • six carbons, • the chemical formula (CH2O)6 or C6H12O6. a key role • in short term energy storage • nearly all the chemical reactions that produce energy for living organisms

monosaccharides six carbon atoms are • Fructose • galactose • mannose. five carbon atoms • Ribose • deoxyribose • xylose • arabinose.

- The open chain structure applies to solutions - Starch, and glycogen, sugars occur in a ring or cyclic structure. -The ring may be six – membered ( pyranose) as in glucose - five membered ( furanose ) as in fructose

Diasccharides • Two monosaccharides linked together form a disaccharide, • e.g. sucrose(table sugar : glucose plus fructose), • Lactose ( milk sugar : glucose plus galactose ), • Maltose ( glucose plus glucose )

Polysaccharides • Polysaccharides are molecules containing numerous monosaccharides usually glucose. e.g.



starch (in plants ) ,



glycogen (in animals) and



cellulose (in plant cell walls).

Starch • Starch is made up of long chains of glucose residues linked by oxygen bridges • between carbon atom number 1 of one residue to carbon atom number 4 of the next.

Chemical structure of starch

Chemical structure of starch • made up of two components, amylose and amylopectin. • Amylose is more soluble in water than amylopectin,

• may be separated from amylopectin by allowing starch grains to stand in water for prolonged periods. • Amylose then dissolves, while the less soluble

amylopectin remains behind

• Amylose dissolves, • while the less soluble amylopectin remains behind. • This difference in behaviour is due to a difference in chain structure. • In amylose the chains are unbranched. • In amylopectin the chains are branched

amylose & amilopectin

• Many short branches, containing about eighteen glucose residues, are linked with other chains of roughly eight glucose residues, forming a highly ramified structure.

Lipids • are insoluble in water. • are classified into three groups : • oils, fats and waxes, • which are similar in structure

• contain carbon, hydrogen and oxy