Cell
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The basic unit of life
A cell is the smallest living part of any organism. It is often called the building block of life because all living things are made up of one or more cells. Some organisms, such as bacteria, are made of just one cell and are called unicellular. Others, like humans, are made of many cells and are called multicellular.
Cells perform many essential functions. They take in nutrients, produce energy, and remove waste. Cells also grow, divide, and respond to their surroundings. In multicellular organisms, different groups of cells work together to form tissues, which then form organs, such as the heart or lungs. Each cell type has a special role, helping the body function properly.
Most cells have certain basic structures. The cell membrane surrounds the cell and controls what enters or leaves. Inside the cell, the cytoplasm is a jelly-like fluid that holds other small parts called organelles. One important organelle is the nucleus, which contains genetic material called DNA. DNA carries instructions that control the cell’s activities and determine inherited traits. Other organelles, like mitochondria, make energy, while ribosomes help build proteins.
There are two main types of cells: prokaryotic and eukaryotic. Prokaryotic cells, found in bacteria, are simple and do not have a nucleus. Eukaryotic cells, found in plants, animals, fungi, and protists, are more complex and contain a nucleus and many organelles. Despite these differences, both types of cells share the same basic life processes.
plant and animal cells have some differences. Plant cells have a rigid cell wall outside the membrane that gives shape and support, and they contain chloroplasts that use sunlight to make food through photosynthesis. animal cells do not have these structures but can move and change shape more easily. Both types of cells contain vacuoles, though they are larger in plant cells and smaller in animal cells.
Scientists study cells using microscopes because most are too small to be seen with the naked eye. The study of cells is called cell biology or cytology. Discoveries about cells have helped people understand how living things grow, heal, and reproduce. Cells are the foundation of all living organisms and continue to be a major focus of biological research.
Cells perform many essential functions. They take in nutrients, produce energy, and remove waste. Cells also grow, divide, and respond to their surroundings. In multicellular organisms, different groups of cells work together to form tissues, which then form organs, such as the heart or lungs. Each cell type has a special role, helping the body function properly.
Most cells have certain basic structures. The cell membrane surrounds the cell and controls what enters or leaves. Inside the cell, the cytoplasm is a jelly-like fluid that holds other small parts called organelles. One important organelle is the nucleus, which contains genetic material called DNA. DNA carries instructions that control the cell’s activities and determine inherited traits. Other organelles, like mitochondria, make energy, while ribosomes help build proteins.
There are two main types of cells: prokaryotic and eukaryotic. Prokaryotic cells, found in bacteria, are simple and do not have a nucleus. Eukaryotic cells, found in plants, animals, fungi, and protists, are more complex and contain a nucleus and many organelles. Despite these differences, both types of cells share the same basic life processes.
plant and animal cells have some differences. Plant cells have a rigid cell wall outside the membrane that gives shape and support, and they contain chloroplasts that use sunlight to make food through photosynthesis. animal cells do not have these structures but can move and change shape more easily. Both types of cells contain vacuoles, though they are larger in plant cells and smaller in animal cells.
Scientists study cells using microscopes because most are too small to be seen with the naked eye. The study of cells is called cell biology or cytology. Discoveries about cells have helped people understand how living things grow, heal, and reproduce. Cells are the foundation of all living organisms and continue to be a major focus of biological research.
What We Can Learn
- Cells are the smallest unit of life.
- All living things are made up of one or more cells.
- Cells have structures like membranes, cytoplasm, and nuclei.
- There are two main types of cells: prokaryotic and eukaryotic.
