Cell Pioneers
He was the first to observe cells in cork using a microscope.
Robert Hooke
What is the first principle of cell theory?
All living things are made up of one or more cells.
In what year did Robert Hooke first observe cork cells?
1665
Why is the cell called the “basic unit of life”?
Because all life functions happen within cells.
The jelly-like substance that fills the cell and holds organelles.
Cytoplasm
He observed living cells and called them "animalcules."
Anton van Leeuwenhoek
What is the second principle of cell theory?
The cell is the basic unit of structure and function in living things.
In the 1670s, he observed microorganisms using a simple microscope.
Anton van Leeuwenhoek
How does observing cells under a microscope help scientists understand life?
It shows how living things are organized and function.
The outer layer that protects the cell and controls what enters and leaves.
Cell membrane
He stated that all plants are made up of cells.
Matthias Schleiden
What is the third principle of cell theory?
All cells come from pre-existing cells.
Schleiden and Schwann proposed the cell theory in what decade?
1830s
What evidence supports that new cells come from existing cells?
Observation of cell division (mitosis).
This structure contains DNA and controls cell activities.
Nucleus
He proposed that all animals are made of cells.
Theodor Schwann
What does the cell theory help explain about living things?
It explains that all living things share a common unit of life — the cell.
Who added the idea that all cells come from pre-existing cells, completing the cell theory?
Rudolf Virchow (1855)
If a new organism is discovered, how could scientists determine if it’s made of cells?
By examining it under a microscope.
These organelles produce energy for the cell.
Mitochondria
He stated that all cells come from pre-existing cells.
Rudolf Virchow
How does the cell theory unify biology?
It shows that all life forms share a common cellular basis.
Arrange these discoveries chronologically: Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow.
Hooke → Leeuwenhoek → Schleiden → Schwann → Virchow
How does the cell theory apply to both unicellular and multicellular organisms?
Both are made up of cells that carry out life processes.
Name one structure found in plant cells but not in animal cells.
Cell wall or chloroplast