Chapter 2: Importance of Carbon

Carbon

  • Although cells are 70-95% water, the rest consists mostly of carbon-based compounds.
  • Carbon forms the backbone of proteins, fats, carbohydrates, and nucleic acids

We all eat at the SPONCH CaFé

  • (but not in that order…HOCNCaPSFe is just too hard to pronounce!!)
  • Percentages don’t vary much from one organism to another.
  • However, because of carbon’s versatility, these few elements can be combined to build an inexhaustible variety of organic molecules.

Organic Chemistry

  • Organic chemistry is the study of carbon containing molecules
  • This includes carbon-containing molecules that are derived from nonliving sources.

A carbon atom

  • Carbon’s atomic number is 6. This means it has 4 valance electrons.
  • It has little tendency to form ionic bonds by loosing or gaining 4 electrons.
  • Instead, it usually completes its valence shell by sharing electrons with other atoms in four covalent bonds.

This tetravalence by carbon makes large, complex molecules possible.

Organic molecule: Building Code

You should commit to memory the valances for the 4 major organic elements:

Carbon = 4, Nitrogen = 3; Oxygen = 2, Hydrogen = 1;

Also remember that carbon can bond to itself and can form double bonds to nitrogen, oxygen and carbon atoms

These give you the basic rules for how organic bonds are made.

Functional Groups

Functional groups are organic molecules that attach to hydrocarbons and are commonly involved in chemical reactions.

Think of it as a generic “person” who can take on different identities with different hats.

Each functional group behaves consistently from one organic molecule to the next.

There are SEVEN functional groups (Page 23 in your book)

Functional Group name / Molecular formula / Structural formula
Carboxyl / -COOH /
Carbonyl / -CO /
Phosphate / -PO4 /
Sulfhydryl / -SH /
Amino / -NH3 /
Hydroxyl / -OH /

Isomer

•An isomer is a compound that has the same numbers of atoms of the same elements but a different structure and different properties

•3 kinds of isomers:

–Structural

–Geometric

–Enantimers

Structural Isomers

–Differ in the covalent arrangement.

–Number of isomers increases as you increase the size of the carbon skeletons

•3 isomers of C5H12, 18 isomers of C8H18, 366,319 isomers of C20H42

Geometric Isomers

–Isomers that have the same sequence of atoms but differ in the spatial arrangement of atoms due to the presence of a double bond.

–Cis and Trans

Enantiomers

–Molecules that are a mirror image of each other.

–Middle carbon is asymmetrical (attached to 4 different atoms or groups of atoms)

–Designated L and D for left (levo) and right (dextro)

–They can’t be superimposed on each other

Macromolecules

Large molecules called macromolecules are formed by covalent linkages of smaller molecules.

There are 4 classes of macromolecules:

  • Carbohydrate
  • Lipid
  • Protein
  • Nucleic Acid

Monomer and polymers

The smaller molecules are called monomers and the macromolecules are also called polymers.

One monomer joins another in a reaction called condensation or dehydration synthesis. They split apart in a reaction called hydrolysis