A Level Biology WJEC

Chemical Elements are Joined Together to form Biological Compounds

Chemical Elements in Biological Compounds

• The basic elements of life are oxygen, hydrogen, carbon, and nitrogen.
• Other elements including phosphorus, sulphur, sodium, potassium, calcium, and magnesium also have important roles within living organisms.
• Trace elements are required in very tiny amounts but are essential for certain cellular functions. These include iron, iodine, copper, zinc, and more.

Formation of Biological Compounds

• Biological compounds, also known as biomolecules, are typically composed of multiple atoms combined.
• The vast majority of these biochemical substances are made up macromolecules, which include proteins, nucleic acids, carbohydrates, and lipids.

Role of Carbon

• Carbon has the unique ability to form stable bonds with other elements, notably itself, which allows it to form a wide variety of functional groups and chains of varying lengths.
• Since carbon has four valence electrons, it easily bonds with hydrogen and other elements to form compounds necessary for life.

Role of Hydrogen Bonds

• Hydrogen bonds play a vital role in the structure and function of biological compounds.
• They contribute to the three-dimensional shape of proteins and nucleic acids and the secondary structure of DNA.

Biomolecules: Protein, Nucleic Acids, Carbohydrates, Lipids

• Proteins are made up of amino acids, linked by peptide bonds. They serve as enzymes, structural proteins and transport proteins, among other functions.
• Nucleic acids are made up of nucleotides, which include one of four nitrogenous bases, a phosphate group, and a sugar. DNA and RNA are types of nucleic acids.
• Carbohydrates, made of simple sugars or polymers of sugars, provide energy and comprise cell structure.
• Lipids are fat-soluble, nonpolar molecules that serve as cell membrane components, hormones, and energy storage.

Water in Biological Systems

• Water plays a fundamental role in the constitution and interaction of biomolecules.
• It allows the correct folding of proteins, the genetic coding by DNA and its transcription to RNA, among other essential functions.

Ionic Compounds in Biological Systems

• Ionic compounds such as salts are critical for the homeostasis of the body and serve in nerve impulse transmission, muscle contraction and hydration.
• Ions such as sodium, potassium, and calcium interact with proteins and other organic compounds, thereby influencing numerous bodily processes.