Important organic chemical FUNCTIONAL GROUPS found in biological molecules (R = any organic group)
This page is for reference. Learn these only as they are discussed in class. They should be memorized so we can talk about them easily.

NAME

GROUP

CHEMICAL EXAMPLE

COMMENT

BIOLOGICAL EXAMPLE

hydroxyl:

-OH

ethanol:  CH₃-CH₂-OH

polar

sugars (e.g., fructose)

aldehyde:

-CHO

acetaldehyde:  CH₃-CHO

polar

glucose

detail:

 O
 ||
-C-H

carboxylic acid:

-COOH

acetic acid:  CH₃-COOH

charged
(ionized)

fatty acid (e.g., oleate)

   detail:

O  || -C-OH

<--->

O   || -C-O^-

<--->

O^-   || -C-O

amine:

-NH₂

methyl amine:  CH₃-NH₂

charged
(ionized)

amino acid (e.g., glycine)

   detail:

(-NH₃⁺)

ketone:

-CO-

acetone:  CH₃-CO-CH₃

polar

metabolic intermediate
(e.g., pyruvic acid)

detail:

O
 ||
-C-

ether:

-O-

ethyl ether:  CH₃-CH₂-O-CH₂-CH₃

not so polar (symmetric)

some lipids

ester:

-COOR

methyl ester of acetic acid:  CH₃-CO-OCH₃

polar. not charged

fats (e.g., triglycerides)

detail:

 O
 ||
-C-O-R

amide:

-CONH₂

acetamide:  CH₃-CONH₂

polar, not charged

proteins (e.g., asparagine)

   detail:

O
 ||
-C-NH₂

sulfhydryl:

-SH

2-mercaptoethanol: HO-CH₂-CH₂-SH

reducing agent

protein (cysteine)

disulfide:

-S-S-

R-S-S-R

crosslinks in proteins

protein (cystine)

phenyl:

phenol:  C₆H₅-OH, Ø-OH

hydrophobic

proteins (phenylalanine)

anhydride

  O O^-
  ||  |
 -C-O-P=O
    ^|
O-

3-phosphogyceric acid: HOCH-CHOH-CO-O-P03^--

2 acids joined

intermediary metabolites

guanidino

 -N-C-NH₂
H ||
NH2⁺

arginine:

⁺H₃N-CH-CH₂-CH₂-CH₂-NH-C-NH₂
          |                                ||
         COO-                         NH₂⁺

charged

proteins (arginine)