Chapter Text
Cell Theory
Timeline:
1665 - Robert Hooke
- First to see cavities, called cells
- First Microscope
1673 - Anton van Leeuwenhoek
- Created 270x microscope
- Saw “animalcules”, now called Protists
1838 - Matthias Schleiden
- Studied plants
- All plants are made from cells
1839 - Theodor Schwann
- Studied animals
- All animal tissues are made of cells
- Wrote first and second part of Cell Theory
1854 - Rudolph Virchow
- All cells must come from other cells
- Wrote third part of Cell Theory
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1. All living things are composed of one or more cells — Theodor Schwann
2. The Cell is the basic unit of Life — Theodor Schwann
3. All cells come from cells that already exist — Rudolph Virchow
Kinds of Cells
Two kinds of cells
- Prokaryotic
- Eukaryotic
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Prokaryotic -
- Simple cells
- Cells WITHOUT a nucleus
- Create Prokaryotes
- Single-Celled organism
- Does NOT have membrane-bound organelles
Two types :
Eubacteria and Archaebacteria
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Eubacteria -
- Most common Prokaryote
- Known as bacteria
- World’s most smallest cell
- Live ALMOST anywhere
Has:
DNA
Ribosomes
- Tiny, round organelles made of protein and other material
Exterior Cell Wall
- Helps the cell retain shape
- Allows material in and out of cell
Cell Membrane
- Inside the Cell Wall
- Allows material in and out of cell
Does NOT Have:
Nucleus
Membrane-covered organelles
Location: Soil, water, in and on other organisms
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Archaebacteria -
- Also known as Archaea
- Single-Celled organisms
Has:
Ribosome
Cell Membrane
- Both Cell Wall and Cell Membrane are DIFFERENT than any other organism
DNA
Does NOT Have:
Nucleus
Organelles
Three Types:
Heat-Loving - Type of Extremophiles : Live in places where conditions are extreme (Very HOT water)
Salt-Loving - Type of Extremophiles : Live in places where conditions are extreme (Hot springs with extremely salty water)
Methane-Making - Kind of gas frequently found in swamps
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Eukaryotic Cells -
- Make Eukaryotes
- Largest Cells
- Microscopic
- 10 times larger than bacterial cells
Has:
Nucleus
- Holds cell DNA
Membrane-bound organelles
- Perform specific functions
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Eukaryotes -
- Can be Single-Celled or Multi-Celled
- Made up of Eukaryotic Cells, meaning Multi-Celled
- Can be seen by the naked eye
Fun Fact: An egg yolk is one BIG cell that provides nutrients for growth!
Additional Cell Material
Cell Size -
- Most cells are too small to be seen without a microscope
- Cells take in food and get rid of waste through their outer surface
- When cells get larger, it needs more food and produces more waste
- Cell’s surface area to volume ratio limits the size of the cell
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Parts of a Cell
Cell Membrane -
- Surrounds all cells
- Phospholipid layer that covers a cell’s surface
- Protective layer… acts as a barrier between the inside of the cell and the cell’s environment
- Controls materials going into and out of the cell
Cytoplasm -
- Inside the cell
- Gel-like fluid
Organelles -
- Found in the cell’s cytoplasm
- Carry out various life processes
- Perform a specific function
Genetic Material: DNA -
- All cells contain DNA at some point in their life
- Genetic material that carries information needed to make new cells
- Passed on from parents
- In some cells, it is enclosed in the organelle called the nucleus (Remember: Bacterial cells do NOT have a nucleus)
- Nucleus processes growth, metabolism, and reproduction
Fun Fact: Human red blood cells have DNA with a nucleus at first, but before they enter the blood stream, it loses both their DNA and the nucleus. They survive with no new instructions!
Next - Animal Cells, Plant Cells and their organelles