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