Level of life
Protein
A chain of amino acids folded into a working shape. Proteins act as enzymes, structures, signals and transporters.
Cell
The smallest unit that can live on its own. Every living thing is made of one or more cells.Source: MedlinePlusSource: NHGRI
Level of life
How Cell connects
Cell is made of
Cell makes up
Level of life
Tissue
A group of similar cells working together, such as muscle, nerve or leaf tissue.
Cell includes
Structure
Nucleus
Stores most of the cell's DNA and controls which genes are used.
Structure
Ribosomes
Build proteins by reading messenger RNA.
Structure
Endoplasmic reticulum
Makes and folds proteins and lipids for membranes and export.
Structure
Golgi apparatus
Modifies, sorts and ships proteins and lipids.
Structure
Mitochondria
Convert energy from food into ATP, the cell's usable energy.
Structure
Lysosomes
Break down and recycle worn-out parts and waste.
Structure
Cell membrane
Controls what enters and leaves the cell.
Structure
Cytoskeleton
Gives the cell its shape and moves things inside it.
Structure
Chloroplasts
Capture light energy to make sugar by photosynthesis.
Structure
Cell wall
A rigid outer layer that supports and protects plant cells.
Structure
Central vacuole
Stores water and keeps plant cells firm.
Cell includes the example
Structure
Stem cells
Cells that can renew themselves and give rise to specialized cells. Adult cells can be reprogrammed into stem-cell-like iPS cells.
Structure
Neuron
A nerve cell that carries electrical and chemical signals. The human brain has about 86 billion of them.
Cell is used by
Organism or group
Virus
Nucleic acid in a protein coat. A virus cannot copy itself alone: it must infect a cell and use the cell's machinery.
Cell is described by
Idea or model
Cells of the human body
An adult has roughly 30 to 37 trillion human cells, and about 90 percent of them belong to the blood-forming lineage.
Idea or model
Minimal cell
A cell stripped to the fewest genes it needs. One synthetic version runs on 473 genes, 149 of which had unknown functions.
Emerging research
Studied in
Your progress
Sources & further reading
The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.
What is a cell? (opens the original in a new tab)
MedlinePlus Genetics. MedlinePlus Genetics. U.S. National Library of Medicine, NIH.
ReferenceGovernment sourceEducationalCell (opens the original in a new tab)
National Human Genome Research Institute. Talking Glossary of Genomic and Genetic Terms. National Human Genome Research Institute, NIH.
ReferenceGovernment sourceEducational