The Cell Theory Important Scientists: Robert Hooke – (1665) observed thin slices of cork and saw a lot of little boxes he called “cells” Anton van Leeuwenhoek – (1674) observed live cells in pond water and called them “animalcules”

Mattias Schleiden – (1838) concluded that plants are made of cells Theodor Schwann – (1839) concluded that animals are also made of cells Rudolph Virchow – (1858) determined that cells come only from other cells

The Cell Theory All living things are made of 1 or more cells. 2. Cells are the basic units of structure & function in organisms. All cells arise from existing cells.

Common Cell Features: cell membrane – outer boundary of a cell that encloses the cell & separates the cell interior from its surroundings; it regulates what enters and leaves the cell. cytoplasm – the cell’s interior; jelly like substance; contains or holds cell’s structures ribosomes – cellular structures on which proteins are made DNA – provides instruction for making proteins; it regulates cellular activities and enables cells to reproduce

Prokaryotes Single celled organisms ex: bacteria NO nucleus NO membrane bound organelles Contains a single circular molecule of DNA Many have cell walls that surround the cell membrane; it provides support and structure Some cell walls are surrounded by a capsule which is composed of polysaccharides Many have flagella which enables it to move

Eukaryotes Single or multicellular organisms ex: plant or animal cells Has a nucleus with DNA inside; linear DNA Has membrane bound organelles that carry our specific activities Have cilia; tiny hair-like structures Has cytoskeleton (protein fibers) that gives the cells shape and support

Eukaryote vs. Prokaryote (Eukaryotic Cell vs. Prokaryotic Cell)

Eukaryotic Cell

What’s different about each cell? DNA (DNA) Membrane-bound