Biology

Functional Groups

Concepts/Ideas/Facts:

1. The structure of complex molecules holds clues to how each kind functions

2. Only living cells can make complex organic compounds

3. Living organisms mainly made up of Carbon, Oxygen, and Hydrogen

4. Carbon forms relatively stable covalent bonds

5. Reactions by which cells build, rearrange, an split apart organic compounds requires not only energy but also enzymes.

Definitions:

1. ORGANINC COMPOUND – molecules that contain Carbon and at least one Hydrogen atom. They have a precise number of atoms arranged in precise ways.  They are simple sugars, fatty acids, amino acids, and nucleotides.

2. HYDROCARBONS – hydrogen atoms covalently bonded to carbon

3. MONOMERS – small organic compounds that when bonded together form larger molecules called polymers

4. POLYMERS - large organic compounds made from bonding together monomers

5. FUNCTIONAL GROUPS – specific atoms or clusters of atoms covalently bonded to carbon.  They give molecules different properties and are the site of chemical reactivity in a molecule.

      A.   HYDROXYL −OH    –  water soluble (hydrophilic) compounds such as sugars, amino acids              and alcohols

      B.   Methyl   R – CH₃   - insoluble (hydrophobic) compounds in fatty acids chains

C.      CARBONYL – water soluble (hydrophilic) compounds in sugars, amino acids, Nucleotides.

a.              aldehyde  −C(=O)H  -  if functional group is at the end of a carbon backbone

  b.       ketone  −C(=O)−

D.      CARBOXYL – highly polar water soluble (hydrophilic) group in amino acids, fatty acids acts as an acid (releases H⁺)

                                 a.    non-ionized   −C(=O)OH    or   −COOH

                                 b.    ionized    −C(=O)O⁻          or      −COO⁻

E.       AMINO ACID – water soluble group in amino acids and nucleotide bases that acts as a weak base.

                                 a.    non-ionized   −NH₂

b.       ionized  −NH₃⁺

                  F.    PHOSPHATE   OPO₃^-2 – water soluble group in nucleotides (ATP), DNA, RNA, many                          proteins, and phospholipids.  Acidic.

G.     SULFHYDRYL (Thiols)  R-SH – strong smelling molecules that bind strongly to skin proteins and are the functional group in the amino acid, cysteine.

6. CONDENSATION REACTIONS (Dehydration Synthesis)– enzyme induces the splitting off of a  −OH  (hydroxyl) from a molecule and an H atom from another molecule which allows a covalent bond to form on the vacated or exposed site.  Basically, water is removed from a monomer to create a polymer from oxygen bonding.  Sometimes discarded atoms form water.
7. HYDROLYSIS – type of cleavage reaction (condensation reversed) where enzymes split molecules, then attach one −OH  (hydroxyl) group and a H atom (from a water molecule) to the exposed site. Hydrolysis cleaves polymers into smaller molecules which can be used later for building blocks or for energy.  Basically water is added to break down polymers (polysaccharides) into monomer (monosaccharides).

Different categories of Reactions (mediated by enzymes)

1.   Functional group transfer – a functional group split away from one molecule is transferred to another.

2.   Electron transfer – an electron split away from one molecule is donated to another

3.      Rearrangement – one type of organic compound is converted to another by a juggling of internal bonds.

4.      Condensation – covalent bonding between two small molecules results in a larger molecule

5.      Cleavage – molecule splits into two smaller ones (Hydrolysis)

GOOD CONDENSATION WEB SITE!    http://www.chem.ed.ac.uk/chemcon/proteins/condense.htm

Good functional group websites:

http://web.mit.edu/esgbio/www/chem/functgroups.html  

http://www.ausetute.com.au/fungroup.html