Zoology Module 1: Carbon in Organic Molecules

Carbon and Organic Molecules

• Carbon is an indispensable element of life, forming multiple bonds and long atom chains.
• The arrangement of carbon groups determines the properties of a carbon-containing molecule.
• Carbon skeletons form the basis of most organic molecules and can vary in length, branching, double bond position, and presence of rings.

Functional Groups

• There are 7 different functional groups directly involved in chemical reactions.
• Hydroxyl group (polar, forms hydrogen bonds with water, compound name: alcohol)
• Carbonyl group (ketone or aldehyde, compound name: ketone or aldehyde)
• Carboxyl group (acts as an acid, compound name: carboxylic acid or organic acid)
• Amino group (acts as a base, compound name: amine)
• Sulfhydryl group (two SH groups can react, compound name: thiol)
• Phosphate group (contributes negative charge, releases energy when combined with water, compound name: organic phosphate)
• Methyl group (affects gene expression, compound name: methylated compound)

Carbohydrates

• Carbohydrates are polyhydroxy aldehydes and ketones, including sugars and polymers of sugar.

• Functions of carbohydrates include:

  • Sources of energy (glucose)
  • Stores energy (glycogen and starch)
  • Structural materials (cellulose and chitin)
  • Cell to cell recognition (plants and fungi create own cell wall)

• Ways to classify carbohydrates:

  • By functional groups (aldehyde or ketone)
  • By number of carbon atoms (triose, tetrose, pentose, hexose)
  • By sugar units (mono, di, poly)

Lipids

• Lipids do not include true polymers and are hydrophobic and varied in form and function.

• Functions of lipids include:

  • Sources of energy (fatty acids and fat-soluble vitamins A, D, E, and K)
  • Stores energy (triglycerides)
  • Structural materials (phospholipids, steroids, and waxes)

• Types of lipids:

  • Fats (hydrocarbon chain + carboxylic acid)
  • Triglycerides (3 fatty acids + glycerol)
  • Phospholipids (phosphate group + glycerol + fatty acid chain)
  • Steroids (cholesterol, fat-soluble vitamins, steroid hormones, and bile salts)
  • Waxes (animal waxes: beeswax, lanolin, spermaceti wax, and feather wax; plant waxes: cuticle and jojoba wax)

Proteins

• Proteins are diverse, polymers of amino acids, and essential for living things.

• Levels of protein structure:

  • Primary structure (chain of amino acids)
  • Secondary structure (coiling or folded pattern stabilized by hydrogen bonds)
  • Tertiary structure (final shape of the polypeptide)
  • Quaternary structure (aggregation of multiple subunits)

• Types of proteins:

  • Structural proteins (provide structural framework and support, e.g., silk, keratin, and collagen)
  • Enzymatic proteins (catalysts, speeding up chemical reactions)
  • Defensive proteins (provide defense against infection and hemorrhage, e.g., antibodies, thrombin, and fibrinogen)
  • Contractile proteins (facilitate movement, e.g., cytoskeleton, motor proteins, and locomotory structures)
  • Transport proteins (carry out transportation of substances, e.g., hemoglobin and transporter proteins)
  • Regulatory proteins (regulate and coordinate organ function, e.g., hormones, growth factors, and transcriptional and translational factors)
  • Receptor proteins (binding site of ligands and participates in signal transduction, e.g., acetylcholine receptors)