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Lecture

Biological Molecules- Carbohydrates + Lipids


Department
Biology (Agric & Envir Sc)
Course Code
AEBI 120
Professor
Gary Dunphy

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September 7th, 2011
Biological Molecules
All lifeforms are composed of carbon, which is the most common element in lifeforms, and
makes up more compounds than all of the other elements combined. This is because it can
form very strong single, double or triple bonds.
Carbohydrates
-Are used as a source of energy (glycogen) or for structure in plants (cellulose)
-(CH2O)n is the general formula
-C6H12O6 + 6O2 <--> 6CO2 + 6H2O
Monosaccarides
-have 3-7 Carbon atoms (often 6, called hexoses)
-glucose (a transport sugar in animals)
-fructose
-deoxyribose (found in genetic material)
Disaccarides
-lactose (glucose-galactose)
-sucrose (a transport sugar in plants)
Oligosaccarides
Polysaccharides
-Contains more than 1000 monosaccharides (usually glucose)
-Glycogen (long term energy in liver, muscles)
-Cellulose (in plants as a structural component)
-Chitin (exoskeleton of insects, lobsters, etc...)
Lipids
-Are usually water insoluble, dissolve organic solvents and have the form of R-O-R or R-OH
Simple
-Fatty acids
-monounsaturated fatty acids
-polyunsaturated fatty acids
-triglyceride (glycerol)
Complex
-phospholipids
-polar head group, and hydrophobic tail
-make up the membrane of cells
Waxes
-Long chain fatty acids, linked to a long chain alcohol or a sterol
-Very soft when warm and hard when cold
-Water insoluble
-Found in insect exoskeletons, on birds’ feathers and on the cuticle of plants
Sterols
-Have 4 rings
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