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๐ฌ Think about it
Some creatures do everything — eat, move, grow, reproduce — with just one cell, while your body needs trillions. How can one cell be enough to be "alive"? Let's find out.
Why is the cell called the basic unit of life?
Why is the cell called the basic unit of life?
Every living body is made of cells
One cell, or many cells together
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A cell holds all the components
Membrane, cytoplasm and nucleus
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It carries out every life process
Even a single cell survives on its own
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So the cell is the basic unit of life
- All living bodies are built from cells.
- A single cell can carry out the functions needed for life.
- So the cell is the smallest living unit.
How are bacterial cells different from other cells?
Does every cell have a true nucleus?
Cells and the nucleus
Not all cells are alike
Bacterial cell
No true nucleus
Has a nucleoid instead
Example:
Bacteria
All other cells
A well-defined nucleus
Example:
Yeast
Protozoa
Algae
Fungi
Plants
Animals
- Bacteria do not have a well-defined nucleus.
- Instead they have a nucleoid (genetic material with no membrane around it).
- This makes them different from plant, animal, fungal, and protozoan cells.
How do the main types of cells compare?
| Feature | Animal Cell | Plant Cell | Fungal Cell | Bacterial Cell |
|---|---|---|---|---|
| Cell membrane | ✓ | ✓ | ✓ | ✓ |
| Cell wall | ✗ | ✓ | ✓ | ✓ |
| Well-defined nucleus | ✓ | ✓ | ✓ | ✗ (has nucleoid) |
| Chloroplast | ✗ | ✓ | ✗ | ✗ |
- All cells have a cell membrane.
- Plant, fungal, and bacterial cells also have a cell wall.
- Only plant cells have chloroplasts; only bacteria lack a true nucleus.
Important Points
- All living things, including microbes, are made of one or more cells.
- Fungal cells have a cell wall but no chloroplasts, so they can't make their own food.
- An electron microscope can magnify a cell about 10,00,000 times.
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Test Yourself
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Why is the cell the basic unit of life?
View Answer
All living bodies are made of cells, and a cell can carry out life's functions. -
What do bacteria have instead of a nucleus?
View Answer
A nucleoid. -
Do fungal cells have chloroplasts?
View Answer
No, so they cannot make their own food. -
Which microscope shows the most detail?
View Answer
The electron microscope (about 10,00,000 times). -
Give one unicellular and one multicellular fungus.
View Answer
Yeast (unicellular); mould (multicellular).
Important Definitions
- Nucleoid — The region in a bacterial cell holding genetic material, without a nuclear membrane.
- Electron microscope — A microscope that magnifies a cell about 10,00,000 times.
๐ NCERT Question 1 — Various parts of a cell
Various parts of a cell are given below. Write them in the appropriate places in the following diagram.
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