Introduction
Basic Chemical Composition of the Cell
The cell is the fundamental unit of life, and like all matter, it's composed of various chemical elements. While numerous elements are found in trace amounts, a select few constitute the bulk of a cell's mass. These primary elements are hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus. The most abundant compound found in cells is water, comprising approximately 99% of the cell's volume. The remaining 1% consists of a complex array of both organic and inorganic molecules, with proteins generally outnumbering DNA in terms of quantity within a cell. It's worth noting that any abnormalities in these biomolecules, the chemical reactions they participate in, or the intricate biochemical pathways they're involved in can often lead to various diseases.
Major Classes of Organic Biomolecules
The primary elements combine to form four major classes of organic biomolecules that are essential for life: nucleic acids, proteins, lipids, and carbohydrates.
- Nucleic Acids: Nucleic acids, namely DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are macromolecules that carry genetic information. These complex molecules are composed of chains of simpler units called nucleotides. Each nucleotide consists of three components: a five-carbon sugar, a phosphate group, and a nitrogenous base. The type of sugar differentiates DNA and RNA: DNA contains deoxyribose, while RNA contains ribose. The phosphate groups link the sugar molecules together, forming a sugar-phosphate backbone, while the nitrogenous bases protrude from this backbone. Nucleic acids can exist as single strands or double strands, with the latter being characteristic of DNA, where two strands are held together by hydrogen bonds between complementary nitrogenous bases.