What is a cell?
Cells are the fundamental building blocks of all living organisms, responsible for providing structure, converting nutrients into energy, and housing the body's hereditary material.
Overview
The human body is composed of trillions of cells. Beyond providing structure, cells take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and possess the ability to make copies of themselves.
Cellular Components
Cells contain many parts, known as organelles, which are specialized structures that perform specific tasks. The major parts of a human cell include:
- Cytoplasm: Made up of a jelly-like fluid called the cytosol and other structures that surround the nucleus.
- Cytoskeleton: A network of long fibers that forms the cell’s structural framework. It determines cell shape, participates in cell division, allows for cell movement, and provides a track-like system for the movement of organelles and other substances.
- Endoplasmic reticulum (ER): An organelle that helps process molecules created by the cell and transports them to their specific destinations inside or outside the cell.
- Golgi apparatus: This organelle packages molecules processed by the endoplasmic reticulum for transport out of the cell.
- Lysosomes and peroxisomes: Acting as the recycling center of the cell, these organelles digest invading foreign bacteria, rid the cell of toxic substances, and recycle worn-out cell components.
- Mitochondria: Complex organelles that convert energy from food into a usable form. They contain their own genetic material, separate from the DNA in the nucleus, and can make copies of themselves.
- Nucleus: The cell’s command center, which sends directions to grow, mature, divide, or die. It houses DNA (deoxyribonucleic acid) and is surrounded by the nuclear envelope, a membrane that protects the DNA and separates the nucleus from the rest of the cell.
- Plasma membrane: The outer lining of the cell that separates the cell from its environment and regulates the entry and exit of materials.
- Ribosomes: Organelles that process the cell’s genetic instructions to create proteins. They may float freely in the cytoplasm or be connected to the endoplasmic reticulum.