Overview
- Biomolecules are chemical compounds common to all living organisms.
- Carbon's bonding versatility underlies biomolecule structure and diversity.
- Functional groups determine biomolecule reactivity and identity.
- Four main biomolecule classes: proteins, carbohydrates, nucleic acids, lipids.
Carbon Structure And Bonding
- Carbon forms stable bonds with H, O, N, P, and S.
- Carbon can bond to itself, forming chains, branched chains, and rings.
- Carbon can form single or double bonds with itself or other elements.
- The carbon chain of a biomolecule is called its skeleton or backbone.
Functional Groups
- Definition: specific bonded-atom groups with consistent chemical properties and predictable reactions.
- Functional groups attach to the carbon backbone (shown as R in diagrams).
- Presence of a functional group changes chemical reactivity and helps identify the biomolecule.
Common Functional Groups In Biology
- Hydroxyl (–OH)
- Example: attachment to a carbon skeleton yields ethanol.
- Carboxyl (–COOH)
- Example: attachment to a carbon backbone can form a fatty acid.
- Amino (–NH2)
- Example: together with a carboxyl group on a backbone forms an amino acid.
- Sulfhydryl (–SH)
- Phosphate (–PO4^3-)
Biomolecule Classes
- Proteins
- Composed of amino acids (contain amino and carboxyl groups).
- Carbohydrates
- Built on carbon backbones with various functional groups.
- Nucleic Acids
- Contain phosphate groups and nitrogenous bases attached to a sugar backbone.
- Lipids
- Often include long hydrocarbon (carbon) chains and carboxyl groups in fatty acids.
Key Terms And Definitions
| Term | Definition |
| Biomolecule | Chemical compound common to living organisms, containing carbon-based bonds. |
| Carbon Skeleton / Backbone | The chain of carbon atoms that defines a molecule’s shape. |
| Functional Group | Specific bonded atoms that confer characteristic chemical properties. |
| Hydroxyl | –OH functional group; increases polarity and reactivity. |
| Carboxyl | –COOH functional group; acidic, found in fatty acids and amino acids. |
| Amino | –NH2 functional group; basic, found in amino acids. |
| Sulfhydryl | –SH functional group; can form disulfide bonds in proteins. |
| Phosphate | –PO4 functional group; important in nucleic acids and energy transfer. |
Examples And Connections
- Methane (CH4) illustrates a simple carbon bonded to four hydrogens.
- Ethanol example: carbon backbone + hydroxyl group → ethanol.
- Fatty acid example: carbon backbone + carboxyl group → fatty acid.
- Amino acid example: carbon backbone + amino + carboxyl groups → amino acid.
Action Items / Next Steps
- Review detailed structures and properties of proteins, carbohydrates, nucleic acids, and lipids in upcoming tutorials.
- Learn common reactions associated with each functional group.
- Practice identifying functional groups and carbon skeletons in molecular diagrams.