A Level Biology Eduqas

Forming Biological Compounds

Forming Biological Compounds

Condensation and Hydrolysis Reactions

• Condensation reactions are processes that result in the formation of large molecules, linked via covalent bonds, with a molecule of water produced.
• In hydrolysis reactions, large molecules are broken down into their constituent parts through the addition of water.

Monomers and Polymers

• Monomers are small, basic molecular units that are capable of binding to other monomers to form more complex structures. Monosaccharides, amino acids, and nucleotides are monomers.
• Polymers are large, complex biomolecules assembled from monomers. Examples include polysaccharides, proteins, and nucleic acids.

Carbohydrates

• Carbohydrates are comprised of carbon, hydrogen and oxygen. They serve as energy stores, structural components, and recognition molecules.
• Monosaccharides are the simplest carbohydrates and serve as monomers for larger carbohydrates. Glucose is a common example.
• Disaccharides are formed from two monosaccharides and are involved in energy storage and transport. Sucrose is a common example.
• Polysaccharides, formed from multiple monosaccharides, serve key roles ranging from energy storage (like starch) to structural support (like cellulose).

Proteins

• Proteins are composed of amino acids connected through peptide bonds.
• A peptide bond is a covalent bond formed between the amino group of one amino acid and the carboxylic group of another, producing water in a condensation reaction.
• Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. Each level contributes to a protein's unique shape and function.

Nucleic Acids

• Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are polymers of nucleotides.
• Nucleotides consist of a phosphate group, a sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.
• DNA carries the genetic information for a cell, and RNA has a variety of roles relating to protein synthesis and regulation.

Lipids

• Lipids are a group of hydrophobic (water-repelling) molecules, not based on repeating monomer units.
• Triglycerides are lipids used for energy storage, while phospholipids form key structural components of cell membranes.
• Steroids, another form of lipid, are involved in many hormonal and structural roles.