Introduction to the Cell Theory
What is a Cell?? Cells – the basic unit of life Organelles - small structures inside a cell with specific functions
Ostrich Egg
1665 – Robert Hooke Coined the term "cells”. Observed cells in cork. Cork Cells
1673- Anton van Leeuwenhoek Created a more improved microscope
1827-33 - Robert Brown -noticed that pollen grains in water jiggled around called “Brownian motion” -discovered the nucleus Nucleus Human Cheek Cell
A botanist who concluded that all plants are made of cells. 1838 - Matthias Schleiden A botanist who concluded that all plants are made of cells. Typical Plant Cell
1839 - Theodor Schwann A zoologist who concluded that all animals are made of cells. Nerve Cells
1855 - Rudolph Virchow A physician who did research on cancer cells and concluded “Omnis cellula e cellula”. “All cells are from other pre-existing cells.”
The Cell Theory 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in an organism. 3. Cells come only from existing cells.
All cells have…… Plasma (cell) Membrane Nucleus (eukaryotes only) Cytoplasm (an area) Organelles (structures with specialized functions)
Cell Types Prokaryotes- simple cells that do not have internal membranes example = bacteria Eukaryotes- more complex cells that do have internal, membrane-bound structures examples = plants and animals
Prokaryotic Vs Eukaryotic
Eukaryotic Organisms: include protists, fungi, plants and animals Timeline Prokaryotic Organisms: First appeared 3.0 BYA include bacteria and cyanobacteria Eukaryotic Organisms: First appeared 2.0 BYA include protists, fungi, plants and animals
Key Differences: Eukaryotes Prokaryotes Have a nucleus and other membrane bounded structures. Have large ribosomes DNA is organized into chromosomes Prokaryotes Lack a nucleus and other membrane bounded structures. Have small ribosomes DNA is not organized into chromosomes
Examples Prokaryotic Eukaryotic Nucleus
Eukaryotic Prokaryotic