The World of Proteins
Discover the molecular machines that power every living cell. From enzymes to antibodies, proteins are the workhorses of life.
What Are Proteins?
Proteins are large, complex molecules essential to all living organisms. They are made up of smaller building blocks called amino acids, linked together in long chains.
There are 20 different amino acids that can be combined in countless ways to create proteins with vastly different structures and functions. The sequence of amino acids determines how the protein folds into its unique 3D shape.
This shape is crucial because it determines what the protein can do in the body. Even a small change in the amino acid sequence can alter the protein's function dramatically.
Key Facts
- 1Proteins make up about 15% of your body mass
- 2Your body contains over 100,000 different proteins
- 3Proteins are encoded by genes in your DNA
- 4The word "protein" comes from Greek "proteios" meaning "primary"
How Proteins Work
Enzymes
Enzymes are protein catalysts that speed up chemical reactions in the body. Without enzymes, reactions that take milliseconds would take years. They help digest food, copy DNA, and produce energy.
Structural Support
Proteins like collagen and keratin provide structural support to cells and tissues. Collagen gives skin its elasticity, while keratin strengthens hair and nails.
Signaling
Hormones and receptors are proteins that allow cells to communicate. Insulin, for example, signals cells to take up glucose from the blood.
Transport
Transport proteins carry molecules throughout the body. Hemoglobin carries oxygen in red blood cells, while membrane proteins move nutrients into cells.
Immune Defense
Antibodies are proteins that recognize and neutralize foreign invaders like bacteria and viruses. They are essential for immune system function.
Movement
Motor proteins like actin and myosin enable muscle contraction. They also help cells divide and transport cargo along cellular highways.
From Gene to Protein
DNA
Contains the genetic code
Transcription
DNA copied to mRNA
Translation
mRNA read by ribosomes
Protein
Functional molecule
The Central Dogma of Molecular Biology
The flow of genetic information follows a specific path: DNA → RNA → Protein. This principle, known as the central dogma, describes how the instructions stored in DNA are used to make proteins.
- Transcription: In the cell nucleus, the DNA sequence of a gene is copied into messenger RNA (mRNA).
- mRNA Processing: The mRNA is modified and transported out of the nucleus to the cytoplasm.
- Translation: Ribosomes read the mRNA and assemble amino acids in the correct order.
- Folding: The amino acid chain folds into a specific 3D shape, creating a functional protein.
Ready to Dive Deeper?
Explore the fascinating world of protein structure or learn about specific proteins that keep your body running.