Fundamental Building Blocks of Life: Elements and Molecules
Components of Living Matter
Composition of Matter
Matter consists of atoms.
Key Definitions
- An atom is formed by small particles.
- Elements are substances that consist of a single type of atom. There are 92 naturally occurring elements.
- Substances are mostly chemical compounds.
Chemical Components: Sources and Examples
Chemical components are unions of different atoms. They originate from:
- Rocks and minerals (inorganic world): For example, marble is calcium carbonate, and gypsum is calcium sulfate. Calcium carbonate is composed of carbon, oxygen, and calcium. Calcium sulfate contains sulfur, oxygen, and calcium.
- Living organisms: Examples include table sugar (sucrose) and egg white (albumin). Sucrose is composed of carbon, hydrogen, and oxygen. Egg albumin contains nitrogen, carbon, hydrogen, and oxygen.
Organic Compounds and Bioelements
Chemical compounds found in the composition of living matter are called organic compounds, characterized by the presence of carbon. While no elements are *exclusive* to living beings, nearly fifty elements have been found in protoplasm. The most abundant are: carbon, hydrogen, oxygen, and nitrogen.
Bioelements and Molecules
Bioelements are well-suited for life because they generally have low atomic weights and form highly water-soluble compounds.
Other less abundant bioelements include: calcium, phosphorus, sulfur, sodium, chlorine, magnesium, and iron.
A molecule is the smallest part of a substance that retains its chemical properties, and from which the substance can be reconstituted without chemical reactions.
Biomolecules: Types and Characteristics
Biomolecules are complex molecules that perform specific functions and evolve with the organisms to which they belong.
Common types of biomolecules include:
- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids
- Vitamins
Each type of molecule has a characteristic structure, which determines its functions within cells.
Some biomolecules are composed of repeated subunits called monomers. When these monomers link together, they form polymers.
Polymers include proteins, nucleic acids, and polysaccharides. Polysaccharides consist of one or two identical monomer units repeated throughout the chain. Proteins and nucleic acids, however, have monomers that can combine in different ways, allowing for greater diversity and differentiation among living organisms.
Non-polymeric biomolecules include vitamins and lipids.
Water and Minerals: Essential Components
In addition to biomolecules, organisms need water and minerals. Water makes up 70% of the content of tissues and is found both inside and outside cells, forming circulating fluids. It allows cells to maintain their shape and helps living things maintain their temperature.
Essential Minerals and Their Functions
Minerals are found in small amounts but are involved in many vital life processes:
- Sodium and potassium: Involved in nerve impulse transmission and maintaining osmotic balance.
- Iron: Involved in the composition of substances like hemoglobin (an oxygen and carbon dioxide-carrying protein in the blood) and respiratory enzymes that enable cellular respiration and energy production.
- Calcium: Involved in bone formation, muscle contraction, and blood clotting.
- Phosphorus: Involved in bone formation and is a component of energy-storing molecules.
- Other essential minerals include: magnesium, fluoride, zinc, and copper.