D’YOUVILLE COLLEGE
BIOLOGY 102 - INTRODUCTORY BIOLOGY II
LECTURE # 4 ORGANIC CHEMISTRY II
2.
Polymers: (fig. 5 – 2 & ppt. 1)
• large molecules composed of many repeating subunit molecules (monomers)
• dehydration (condensation) synthesis: linkages between monomers in a
polymer are formed by loss of water from the two monomers
• hydrolysis: digestion of polymers; links between monomers are broken by
addition of water
3.
Carbohydrates:
• important energy sources
• composed mainly of carbon, hydrogen and oxygen combined as polyhydroxy
aldehydes & ketones
in monomers (simple sugars) ratio of different atoms is:
Cn(H2O)n
• simple sugars (monosaccharides): chains of carbon atoms, each with hydroxyl
group (usually 5 or 6 = hexose or pentose); terminal or secondary carbonyl – aldoses or
ketoses (fig. 5 – 3 & ppt. 2) e.g. glucose, galactose, fructose & ribose
- form rings (fig. 5 – 4 & ppt. 3)
- derivative monosaccharides are simple sugars with functional groups
containing other elements, e.g. amino group (glucosamine), phosphate group (glucose
phosphate), sulfate group
• compound sugars (disaccharides): two monosaccharides linked together; e.g.
sucrose, maltose, lactose; formation of linkage via dehydration synthesis (fig. 5 – 5 & ppt.
4)
• “complex” carbohydrates (polysaccharides): large molecules composed of large
numbers of monosaccharides linked together (figs. 5 – 6, 5 – 7, 5 – 8, ppts. 5, 6 & 7); e.g.
starches, glycogens, celluloses – polymers of glucose
- chitins (in insect exoskeletons, suture thread) – polymers of Nacetylglucosamine)(fig. 5 – 10 & ppt. 8)
Biology 102 - Spring ‘12
page 2
4.
Lipids:
• non-polar compounds; diversified structural characteristics, featuring
extensive hydrocarbon chains
• important energy sources
• neutral fats/oils: fatty acids combined with glycerol to form triglycerides via
dehydration synthesis (fig. 5 – 11 & ppt. 9)
- saturated, long chain fatty acids (16 - 20 C) with no double C=C bonds, usually
found in animal fats
- unsaturated, shorter chain fatty acids, containing one or more double C=C
bonds, usually found in vegetable oils (liquid at room temperature) fig. 5 – 12 & ppt. 10)
• phospholipids (figs. 5 – 13, 5 – 14, ppts. 11 & 12): contain polar groups
(including phosphorus) in combination with glycerol (phosphoglycerides)
- polar & non-polar regions facilitate special interactions in aqueous media
resulting in lipid bilayer organization; important in cell membrane structure
• steroids (figs. 4 – 9, 5 – 15, ppts. 13 & 14): complex ring structure (steroid
nucleus) derived from cholesterol - parent compound of steroids
- hormones, digestive agents & cell membrane components, e.g. sex
hormones, adrenal cortical hormones & bile salts