Nepedia
Back to Discover
Advanced Reader
🧬

Biomolecule

life science Maturity 9-11 Next article →

Biomolecules are molecules produced by living organisms that are essential to biological processes. They are the fundamental building blocks of life. These molecules can be small, such as vitamins or hormones. They can also be large macromolecules, such as proteins, carbohydrates, lipids, and nucleic acids. Because they are so important to life, they are often called biological materials. Most biomolecules are endogenous, meaning the organism produces them internally. However, organisms also require exogenous biomolecules, like certain nutrients, to survive.

Myoglobin
Myoglobin

Most biomolecules are organic compounds made of specific elements. In the human body, oxygen, carbon, hydrogen, and nitrogen make up 96% of the total mass. Other elements, such as various biometals, are also present in small amounts. Despite the massive diversity of life on Earth, many biomolecules and metabolic pathways are the same across different species. Scientists call these biochemical universals. This concept of material unity is a major idea in biology, alongside cell theory and evolution theory.

Nucleic acids are important polymers that manage genetic information. DNA and RNA are both made of repeating units called mononucleotides. Each nucleotide contains a nitrogenous base, a pentose sugar, and one to three phosphate groups. DNA typically forms a double helix through Watson-Crick base-pairing. In this structure, Cytosine (C) pairs with Guanine (G), and Adenine (A) pairs with Thymine (T). This is known as B-form DNA. RNA is different because its pentose ring has an extra hydroxyl group. RNA can form complex 3D structures, such as those found in ribosomes or ribozymes.

Twort groupI intron RNAribbon stereo
Twort groupI intron RNAribbon stereo

Proteins are large molecules built from chains of amino acids. The specific sequence of these amino acids is known as the primary structure. This sequence is determined by an individual's genetic makeup. Proteins then fold into a secondary structure using hydrogen bonds. One common shape is the alpha helix, which is a regular spiral. Another is the beta pleated sheet, which consists of extended strands. The final, compact 3D shape is called the tertiary structure or the fold.

Myoglobin
Myoglobin

Saccharides, or carbohydrates, include a wide variety of structures. Monosaccharides are the simplest form, containing only one sugar. Examples include glucose, fructose, and ribose. When two monosaccharides bond, they form a disaccharide, such as sucrose or lactose. These are created through a process that removes a water molecule. Larger molecules called polysaccharides are formed by many linked sugars. Examples include starch, cellulose, and glycogen. While small sugars dissolve easily, large polysaccharides are often not water-soluble.

Lipids serve as the building blocks for biological membranes and energy storage. Most lipids consist of a hydrophilic head and one to three hydrophobic tails. This makes them amphiphilic, meaning they have both water-loving and water-fearing parts. Fatty acids make up the tails of these lipids. These chains consist of an even number of carbon atoms, usually between 14 and 24. Different types of lipids include phospholipids, which have a negatively charged phosphate group. Other types include sterols, like cholesterol, and glycolipids.

Lignin is another important biopolymer, especially in plants. It is the second most abundant biopolymer after cellulose. Lignin is a complex macromolecule made of subunits like coniferyl alcohol. It is unusual because it is racemic, meaning it lacks optical activity. This happens because lignin forms through free radical coupling reactions. These reactions do not prefer one specific configuration at a chiral center. This structural component is vital for the strength of most plants.

Our understanding of these molecules has grown through scientific discovery. In 1958, Max Perutz and John Kendrew solved the structure of myoglobin. They used a technique called X-ray crystallography to do this. This was a landmark moment in biochemistry. Their work on protein structures earned them a Nobel Prize in Chemistry. Today, scientists study these molecules in the fields of biology, biochemistry, and molecular biology to understand how life functions at the most basic level.

640 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (2)
File:Myoglobin.png
Myoglobin.png
File:Twort groupI intron RNAribbon stereo.jpg
Twort groupI intron RNAribbon stereo.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.