These class notes on cells focus on the structure and function of prokaryotic and eukaryotic cells, outlining Cell Theory and emphasizing the key differences between these two cell types. The notes explain that all cells have a plasma membrane, cytoplasm, DNA, and ribosomes. Additionally, they deta...
Cells: Intro and Membranes
Cells
Cell Theory
1. All living things are composed of one or more cells.
2. All cells come from pre-existing cells.
All cells have:
1. A plasma membrane - outer layer that separates the contents of the cell from the
environment.
2. Cytoplasm - the liquid (cytosol) contained by the membrane and everything susp
3. DNA - Hereditary material of all life
4. Ribosomes - protein makers
There are two different major types of cells:
• Prokaryotic:
• Found in bacteria and archaea.
• All single celled
• “Prokaryotes”
• Eukaryotic:
• found in everything else:
§ Animals
§ Plants
§ Fungi
§ Protists
• “Eukaryotes” can be single celled or multicellular.
Prokaryotic cells are smaller and simpler than eukaryotic cells.
Eukaryotic cells have organelles - membrane-enclosed subunits of various functions.
• For example: a nucleus where DNA is held
Cell Membrane
All cell types
• Main components are phospholipids.
• Phospholipids have:
w A hydrophobic "tail"
w A hydrophilic "head"
Plasma Membrane
ALL cells have a plasma membrane composed of phospholipid bilayer.
The plasma membrane acts as a barrier and a gatekeeper.
Diffusion
Diffusion describes the spread of particles through Random motion from regions of hi
concentration to regions of lower concentration.
"Equilibrium" - spread out evenly
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