Key Points
Key Points
- Anything that has mass and takes up space is matter and matter is composed of elements. Elements are unique substances that cannot be broken down or changed chemically into another substance. Carbon (C), hydrogen (H), nitrogen (N), oxygen (O), sulphur (S) and phosphorus (P) are the key components of chemicals found in all living things.
- The nucleus of atoms contain positively charged protons and neutrally charged neutrons. The mass of an atom is equal to the number of protons and neutrons of that atom. Atoms combine to form molecules via ionic, covalent, hydrogen or van de Waals bonds. To form these bonds, electrons can be donated (ionic bonds) or shared (covalent bonds). Hydrogen bonds form due to electrical attraction of a hydrogen molecule that has a covalent bond (such as water). Van der Waals interactions are the weakest type of bonding and is similarly due to electrical interactions between atoms, in this case being temporary changes in charge.
- The essential element for all life on Earth is carbon. The four main types of biological molecules: carbohydrates, lipids, proteins, and nucleic acids, comprise largely of carbon. These molecules provide energy, make up support structures and cell components, and serve in transport, storage and protective functions to maintain homeostasis.
- The primary structure of protein contributes to the protein structure and function. A change to the unique sequence of amino acids can result in altered function of the protein such as the case in sickle cell anaemia, where a change in a single amino acid result in abnormal haemoglobin molecules.
- Water is essential to life. The polarity of water allows attraction of polar molecules, allowing dissolution of hydrophilic substances such as sugar, and giving water it’s important characteristics as a solvent. Water absorbs a great deal of energy before its temperature is affected, making it suitable for stabilisation of temperature. Water molecules are also cohesive. Cohesion and adhesion are important life sustaining forces which allow water to flow up from the roots to the tops of plants.
