Biological Chemistry

Session 4

Squamish The Chief

Functional Groups in Organic Compounds

v  Most organic compounds are chains or rings of carbon and hydrogen

v  What makes organic molecules different from each other are their functional groups

v  “R” is a general symbol used to represent the functional group (also known as a radical group)

1. Alcohols

l  General formula: OH

l  Group called hydroxyl group

l  General name: ends in “ol”

l  OH group is polar (.:water soluble)

l  Can have more than one OH group

l  Examples: v  ethanol (drinking alcohol), cholesterol, glycerol

l  Many are toxic v  eg. methanol (wood alcohol), can cause blindness

2. Aldehydes

l  General formula: CHO

l  General name: ends in “al”

l  The C = O group is called the carbonyl group

v  Polar (.:water soluble)

l  Examples:

v  formaldehyde (methanal): embalming fluid

v  acetaldehyde (ethanal): smog

3. Ketones

l  General formula: (on board)

l  General name: ends in “one”

l  Polar carbonyl group ∴ water soluble

l  Often used as solvents

l  Examples: v  Acetone

v  Cortisone

v  Progesterone

4. Organic Acids/ Carboxylic Acids

l  General formula: COOH

l  General name: ends in “(o)ic acid”

l  Called carboxyl group

l  Acidic: R—COOH → R—COO- + H+

l  If chain is short → water soluble

l  If have long hydrocarbon chains → fatty acids

l  Examples:

v  acetic acid, vinegar

v  formic acid, ant/bee stings

5. Amines

l  General formula: NH2

l  Group is called amino group

l  General name: ends in “amine”

l  Water soluble

l  Weak bases: R-NH2 + H+ → R-NH3+

l  Example:

v  amino acid

6. Ethers

l  General formula: O

l  General name: ends in “ether”

l  Examples:

v  diethyl ether, decongestant

7. Esters

l  General formula: (on board)

l  General name: ends in “(o)ate”

l  Responsible for flavour/odor of many foods

l  Fats and oils are esters

l  Examples:

v  ethyl formate, rum

v  pentyl acetate, banana

v  octyl acetate, orange

Chemical “Food” Artificial Strawberry Flavour

Source: Fast Food Nation, Eric Schlosser, page 125-126

8. Amides l  General formula: (see board)

l  General name: ends in “amide”

l  Examples:

v  eg. proteins and nylon

9. Sulfhydryls

l  General formula: SH

l  Group called thiol group

l  General name: ends in “thiol”

l  Small thiols produce foul odors

l  Examples:

v  butenethiol: skunks

v  propanethiol: onions/garlic

10. Disulfides

l  General formula: S S

l  Thiols in proteins form disulfide bridges

l  Important in determining the characteristic shape of proteins

11. Phosphates l  General formula: (see board diagram)

l  Group called phosphate group

l  Present in ATP (adenosine triphosphate)

•  Assignment #3 •  Work on it for remainder of class •  Hand in today if done •  Hand in next class if need more

time •  Homework

•  Review Chapter 10 •  Next class

•  Chapters 12, 13, 14