cells the basic units of life. cell theory robert hooke was the first person to describe cells in...
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Cell Theory
Robert Hooke was the first person to describe cells in 1665.
He observed cork cells and plant cells, which are easier to see because of a cell wall.
Animal cells are harder to see, so he thought animals weren’t made up of cells since he couldn’t see them.
Anton van Leeuwenhoek
Discovered animalcules (which means little animals)
Now known as Protists (single-celled organisms)
Discovered cells in animal blood. Found differences between blood cells of
different animals. First person to see bacteria
Cell TheoryMatthias Schleiden and Theodor Schwann
Schleiden studied plants – Discovered all plants are made of cells
Schwann studied animals – discovered that all animal tissue is made of cells.
Schwann wrote first 2 parts of cell theory
All organisms are made of one or more cells
The cell is the basic unit of all living things
Cell Theory
Rudolf Virchow added the 3rd part to the cell theory in 1858
All cells come from existing cells
Common cell parts There are many different types of cells – But all cells have a few parts in common
Cell membrane and cytoplasm Organelles Genetic material
Cell Membrane & Cytoplasm
All cells are surrounded by a cell membrane
The cell membrane is a protective layer that covers the cell’s surface and acts as a barrier
It also controls materials going into and out of the cell
Cytoplasm is the fluid inside a cell
Organelles Structures that perform specific
functions within the cell. Most are surrounded by membranes Some float in the cytoplasm Some are attached to membranes or
other organelles
Genetic Material All cells contain DNA DNA is the genetic material that carries
information needed to make new cells and new organisms
DNA is passed from parent to offspring and controls the activities of a cell
2 Types of Cells Prokaryotes and eukaryotes Prokaryotes are single-celled organisms
that do not have a nucleus or membrane-bound organelles
Eukaryotes are an organism made of cells that have a nucleus enclosed by a membrane
Prokaryotes Single-celled organism Do not have a nucleus Ex: Bacteria and Archaea Bacteria are the most common
prokaryote No Nucleus, no membrane-covered
organelles Do have ribosomes, and a strong cell
wall
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