Chemistry Functional Groups

Organic Chemistry The study of carbon-containing compounds Carbon atoms are the most versatile building blocks of molecules With a total of 6 electrons, a carbon atom has 2 in the first shell and 4 in the second shell Carbon usually completes its valence shell by sharing electrons with other atoms in four covalent bonds This tetravalence by carbon makes large, complex molecules possible

Carbon Chains form the skeletons of most organic molecules the skeletons may vary in length and may be straight, branched, or arranged in closed rings the carbon skeletons may also include double bonds

Isomers Structural isomers Geometric isomers Enantiomers

Structural Isomers Variation in covalent partners Pentane has a straight skeleton and isopentane has a branched skeleton Same molecular formula C5H12

Geometric Isomers Variation in arrangement about a double bond Example: rhodopsin (in the retina) from one geometric isomer to another

Enantiomers Variation in spatial arrangement, mirror images enantiomers are possible if there are four different atoms or groups of atoms bonded to a carbon they are like left-handed and right-handed versions usually one is biologically active, the other inactive

Functional Group A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and usually involved in chemical reactions

Hydroxyl -OH Carbonyl CO Carboxyl -COOH Amino -NH2 Sulfhydryl -SH Phosphate -PO4-2 (-OPO3-2) Methyl -CH3

1.Hydroxyl Group (-OH) a hydrogen atom forms a polar covalent bond with an oxygen which forms a polar covalent bond to the carbon skeleton Organic compounds with hydroxyl groups are alcohols and their names typically end in –ol example ethanol

2.Carbonyl Group ( CO) consists of an oxygen atom joined to the carbon skeleton by a double bond ketone - if not at the end example: acetone aldehyde -if the carbonyl group is on the end of the skeleton example: propanal

3.Carboxyl Group (-COOH) carbon atom with a double bond with an oxygen atom and a single bond to a hydroxyl group. carboxylic acids – compounds with carboxyl groups Acidic properties - because the combined electro negativities of the two adjacent oxygen atoms increase the dissociation of hydrogen as an ion (H+) Example: acetic acid (vinegar)

4. Amino Group (-NH2) Nitrogen atom attached to two hydrogen atoms and the carbon skeleton. Amines - Organic compounds with amino groups. Basic properties - because ammonia can pick up a hydrogen ion (H+) from the solution Example: amino acids

5. Sulfhydryl Group (-SH) sulfur atom bonded to a hydrogen atom and to the backbone thiols - organic molecules with sulfhydryl Sulfhydryl groups help stabilize the structure of proteins Example: amino acid Cysteine

6. Phosphate Group (-OPO3-2) Phosphorus bound to four oxygen atoms (three with single bonds and one with a double bond). Phosphate groups are anions with two negative charges as two protons have dissociated from the oxygen atoms. One function of phosphate groups is to transfer energy between organic molecules. Example ATP

7. Methyl Group (-CH3) Carbon bonded to 3 hydrogen atoms. The methyl group may be attached to a or a different atom. Addition of methyl to molecule changes its shape and function Example: 5-Methyl cytidine

Activity Identify the functional groups

C - N H H Methylamine H H H H H O Alanine N - C - C OH H CH3

Activity Identify the functional groups

ATP (adenosine triphosphate) The End