Chapter 4: Carbon

Hydrocarbons

• Organic molecules consisting of only carbon and hydrogen.

• Found in many organic molecules, such as fats (lipids).

• Undergo reactions that release a large amount of energy.

Versatility of Carbon

• Carbon has 4 valence electrons, allowing it to form four covalent bonds.

• This enables the formation of large, complex, and diverse organic molecules.

• Carbon skeletons vary in length and shape, contributing to biological diversity.

Functional Groups

• Functional groups are covalently bound to the carbon backbone and are commonly involved in chemical reactions.

• Example: Testosterone vs. Estradiol have the same carbon structure but different functional groups, leading to different biological effects.

• 7 Key Functional Groups (know their structure & function):

  1. Hydroxyl (-OH) – Increases solubility, helps form H-bonds.

  2. Carbonyl (C=O) – Found in sugars, structural role.

  3. Carboxyl (-COOH) – Acts as an acid, donates H+.

  4. Amino (-NH2) – Acts as a base, picks up H+.

  5. Sulfhydryl (-SH) – Forms covalent bonds in proteins.

  6. Phosphate (-OPO3^2-) – Confers negative charge, helps in energy transfer (e.g., ATP).

  7. Methyl (-CH3) – Affects gene expression and function.

ATP (Adenosine Triphosphate)

• Primary energy-transferring molecule in cells.

• Composed of adenosine attached to three phosphate groups.

• The phosphate group is negatively charged, giving ATP the ability to react with water.

• Hydrolysis of ATP (removal of a phosphate group) releases energy used for cellular processes.

Isomers

• Isomers are molecules with the same molecular formula but different structures.

• Types of Isomers:

  • Structural Isomers – Differ in the arrangement of atoms.

  • Cis-Trans Isomers – Differ in spatial arrangement around a double bond.

  • Enantiomers – Mirror images of each other (important in pharmaceuticals).

    • Example: Two enantiomers of a drug may have different biological effects.