LE 4-4

Hydrogen

(valence = 1)

Oxygen

(valence = 2)

Nitrogen

(valence = 3)

Carbon

(valence = 4)

LE 4-5

LengthEthane Propane

Butane 2-methylpropane(commonly called isobutane)

Branching

Double bonds

Rings

1-Butene 2-Butene

Cyclohexane Benzene

LE 4-7

Structural isomers differ in covalent partners, as shown in this example of two isomers of pentane.

Geometric isomers differ in arrangement about a double bond. In these diagrams, X represents an atom or group of atoms attached to a double-bonded carbon.

cis isomer: The two Xsare on the same side.

trans isomer: The two Xsare on opposite sides.

L isomer D isomer

Enantiomers differ in spatial arrangement around an asymmetric carbon, resulting in molecules that are mirror images, like left and right hands. The two isomers are designated the L and D isomers from the Latin for left and right (levo and dextro). Enantiomers cannot be superimposed on each other.

LE 4-10aa

STRUCTURE

(may be written HO—)

NAME OF COMPOUNDS

Alcohols (their specific names

usually end in -ol)

Ethanol, the alcohol present in

alcoholic beverages

FUNCTIONAL PROPERTIES

Is polar as a result of the

electronegative oxygen atom

drawing electrons toward itself.

Attracts water molecules, helping

dissolve organic compounds such

as sugars (see Figure 5.3).

LE 4-10ab

STRUCTURE

NAME OF COMPOUNDS

Ketones if the carbonyl group is

within a carbon skeleton

EXAMPLE

Acetone, the simplest ketone

A ketone and an aldehyde may

be structural isomers with

different properties, as is the case

for acetone and propanal.

Aldehydes if the carbonyl group is

at the end of the carbon skeleton

Acetone, the simplest ketone

Propanal, an aldehyde

FUNCTIONAL PROPERTIES

LE 4-10ac

STRUCTURE

NAME OF COMPOUNDS

Carboxylic acids, or organic acids

EXAMPLE

Has acidic properties because it isa source of hydrogen ions.

Acetic acid, which gives vinegarits sour taste

FUNCTIONAL PROPERTIES

The covalent bond betweenoxygen and hydrogen is so polarthat hydrogen ions (H+) tend todissociate reversibly; for example,

Acetic acid Acetate ion

In cells, found in the ionic form,which is called a carboxylate group.

LE 4-10ba

STRUCTURE

NAME OF COMPOUNDS

Amine

EXAMPLE

Because it also has a carboxyl

group, glycine is both an amine and

a carboxylic acid; compounds with

both groups are called amino acids.

FUNCTIONAL PROPERTIES

Acts as a base; can pick up a

proton from the surrounding

solution:

(nonionized)

Ionized, with a charge of 1+,under cellular conditions

Glycine

(ionized)

LE 4-10bb

STRUCTURE

(may be written HS—)

NAME OF COMPOUNDS

Thiols

EXAMPLE

Ethanethiol

FUNCTIONAL PROPERTIES

Two sulfhydryl groups can

interact to help stabilize protein

structure (see Figure 5.20).

LE 4-10bc

STRUCTURE

NAME OF COMPOUNDS

Organic phosphates

EXAMPLE

Glycerol phosphate

FUNCTIONAL PROPERTIES

Makes the molecule of which it

is a part an anion (negatively

charged ion).

Can transfer energy between

organic molecules.

Table 4.1 Functional Groups of Organic Compounds

LE 4-9

Estradiol

Testosterone

Male lion

Female lion

Common Elements found in living organisms

Molecular Composition of 2 cells

LE 5-2a

Short polymer Unlinked monomer

Dehydration removes a watermolecule, forming a new bond

Dehydration reaction in the synthesis of a polymer

Longer polymer

LE 5-2b

Hydrolysis adds a watermolecule, breaking a bond

Hydrolysis of a polymer

The molecules of life

• Carbohydrates (C,H,O)-monomer is a monosaccharide and polymers are polysaccharides

• Lipid-(C,H,O)-in triglycerides (polymer) the 2 monomers are glycerol and fatty acids. Steroids lipids are not monomers or polymers

• Proteins (C,H,O,N,S)-monomers are amino acids and the polymers are polypeptides

• Nucleic acids (C,H,O,N,P)-monomers are nucleotides and the polymers are polynucleotides.