Cell Biology
Subject: Basic Biology
A cell is the basic unit of life. All living organisms are made up of one or more cells.
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Cell Theory
The three main points of the cell theory are:
All living things are made of cells.
The cell is the basic unit of structure and function in living things.
All cells come from pre-existing cells.
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Types of Cells
1. Prokaryotic Cells
Simple cells without a nucleus
No membrane-bound organelles
Example: Bacteria
2. Eukaryotic Cells
Complex cells with a nucleus
Have membrane-bound organelles
Examples: Plants, animals, fungi, protists
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Cell Structures (Organelles) and Their Functions
Nucleus: Controls cell activities and contains DNA
Cell membrane: Controls what enters and leaves the cell
Cytoplasm: Jelly-like fluid where chemical reactions take place
Mitochondria: Produces energy (ATP), known as the "powerhouse" of the cell
Ribosomes: Make proteins
Endoplasmic Reticulum (ER): Transports materials within the cell
Golgi Apparatus: Packages and ships proteins
Lysosomes: Break down waste and old cell parts
Chloroplasts (in plant cells only): Carry out photosynthesis
Cell wall (in plant cells only): Gives structure and protection
Vacuole: Stores water, nutrients, and waste
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Differences Between Plant and Animal Cells
Plant cells have a cell wall; animal cells do not.
Plant cells have chloroplasts for photosynthesis; animal cells do not.
Plant cells usually have a large central vacuole; animal cells have small or no vacuoles.
Plant cells are more rectangular; animal cells are more rounded.
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Cell Membrane and Transport
The cell membrane is selectively permeable, which means it controls what enters and leaves the cell.
Types of Transport:
Passive Transport (no energy needed):
Diffusion: Movement of particles from high to low concentration
Osmosis: Movement of water across a membrane
Active Transport (requires energy):
Moves substances from low to high concentration using energy (ATP)
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Cell Division
Mitosis: Produces two identical cells; used for growth and repair
Meiosis: Produces sex cells (sperm and egg); reduces the number of chromosomes by half
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Why Cell Biology Matters
Cell biology helps us understand how our bodies work, how diseases like cancer begin, and how we can use science to develop new treatments and technologies in health, medicine, and agriculture.
By:
Adam Umar
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