Molecular & Cellular Biology Department of Biological Sciences Functional Groups Molecular & Cellular Biology Department of Biological Sciences 05/2002 RGratreaks 11/21/2018 Based on Interactive Study Partner for Biology, 5th edition.
Functional Groups 11/21/2018
Functional Groups Groups of atoms with distinctive properties, called functional groups, attached to the carbon skeleton. This is an organic molecule called a tripeptide. 11/21/2018
Functional Groups Carboxyl Hydroxyl Carbonyl Sulfhydryl Amino Phosphate 11/21/2018
What is this Functional Group?
Amino
What is special about Amino? The slightly electronegative nitrogen atom in this group tends to pick up hydrogen ions from the surrounding solution, and thus this functional group acts as a base. Because of the added hydrogen ion, this group usually has a +1 charge in the cell. This group is characteristic of organic molecules called amines.
What is this Functional Group?
Carbonyl
What is special about Carbonyl? This group is polar because oxygen has a strong attraction for electrons. If this group is at the end of a carbon skeleton, the molecule is called an aldehyde; otherwise it is called a ketone.
What is this Functional Group?
Carboxyl
What is special about Carboxyl? The two electronegative oxygens of this group pull electrons away from the hydrogen atom. This weakens the bond between oxygen and hydrogen, and the hydrogen atom tends to dissociate from the molecule as a hydrogen (H+) ion. Because it donates hydrogen ions, this group is acidic, and molecules that contain these groups are known as carboxylic acids.
What is this Functional Group?
Hydroxyl
What is special about Hydroxyl? This functional group is polar because the electronegative oxygen has a strong attraction for electrons. Water is attracted to this group, and therefore molecules that have this group (such as sugars) tend to dissolve in water. Alcohols are characterized by this functional group.
What is this Functional Group?
Phosphate
What is special about Phosphate? The electronegative oxygens of this functional group draw electrons, and as a result the group acts as an acid, losing hydrogen ions to the surrounding solution. This dissociation leaves the group with a negative charge. This group is important in ATP and the transfer of energy between organic molecules.
What is this Functional Group?
Sulfhydryl
What is special about Sulfhydryl? Molecules termed thiols are characterized by this group, which resembles a hydroxyl group. These groups interact to help stabilize the structure of many proteins.