Chapter Four: Isomers and Functional Groups

Isomers are compounds with the same molecular formula but with different structures and hence different properties. Isomers are a source of variation among organic molecules.

There are three types:
Structural isomers, geometric isomers, and enantiomers:

Structural Isomers are isomers that differ in the covalent arrangement of their atoms
Same molecular formula, skeleton may change, and can differ in location of double bonds
EXAMPLE: C4H10

Geometric Isomers are isomers that share the same covalent partnerships, but differ in their spatial arrangement
Double bonds are inflexible

EXAMPLE:

Enantiomers are isomers that are mirror images of each other
Usually one form is biologically active and its mirror image is not

EXAMPLE:
For Parkinsons patients, L-Dopa helps control involuntary shaking. However, its mirror image, D-Dopa does not help with symptomsm, and when given to some patients, can cause death. Scientists learned the hard way that enantiomers, although they have the same molecular formula, do not have the same properties.

Functional groups also contribute to the molecular diversity of life.
Small characteristic groups of atoms (functional groups) are frequently bonded to the carbon skeleton of organic molecules.

1. Hydroxyl group: alcohols -OH
Makes the molecule to which it is attached water soluble
EXAMPLE: Isopropyl Alcohol (rubbing alcohol)
The –OH bonded to the carbon is what makes the molecule an alcohol

2. Carbonyl Group: Aldehydes and Ketones are characterized by the Carbonyl Group

Aldehyde- carbonyl is AT THE END of the carbon skeleton

EXAMPLES:

Ketone: carbonyl is IN THE MIDDLE OR NEAR THE END of the carbon
Skeleton
EXAMPLES:

3. Carboxyl Group: carboxyl acids are characterized by the carboxyl group:

Since this group donates proteins it has acidic properties

EXAMPLE: Acetic Acid
4. Amino Group: Characterized by Nitrogen joined to at least one alkyl group: -NH2

Tends to act as a weak base (accepts protons)

EXAMPLE: Glycine

5. Sulfhydryl Group: -SH
Helps stabilize the structure of protein. Example: Disulfide bridges help stabilize tertiary structure proteins.

Organic compounds with this functional group are called thiols.

EXAMPLE: Cysteine

6. Phosphate: PO4 -3
Has acidic properties since it loses protons
Organic phosphates are important in cellular energy storage and transfer.

EXAMPLE: Glycerol Phosphate

7. Methyl Group: -CH3 , is a nonpolar hydrophobic functional group

EXAMPLE: 5-Methyl Citidine
These are today's notes.

We also talked about aspirin, ibuprofren, acetaminophen, and when you should use them. Studies have shown that one baby aspirin each day helps lower the risk of stroke and heart attack because it thins your blood!

Remember:

Thursday- Chapter 5 notecards are due, Chapter 4 quiz, Chapter 4 vocab quiz

Friday- Chapter 5 vocab quiz, Test Corrections are due (try to get them in Thursday)

HAVE AN EXCELLENT NIGHT!