Cells were unknown until the discovery of microscopes in the 1650’s

two scientists working independently built the first microscopesAnton von Leeuwenhoek in HollandRobert Hooke in England

Studied cork - a kind of tree bark

named the structures he saw “cells” because they reminded him of the small rooms monks slept in

Studied pondwater, sour milk, and semen (magnification 10X greater than Hooke’s)

named moving organisms “animalcules” this scared people who thought:Human sperm cells contain tiny

human beings!Pond water causes madness

Today we can look back and think “crazy,” but at the time people took these ideas very seriously.

(protists)

1. All living things are composed of cells (you, me, plants, bugs, fish, bacteria, yeast,)

2. Cells are the basic units of structure and function in living things(what keeps us upright and helps us live, basically small workers responsible for how we function!)

3. New cells are produced from existing cells(they can’t just appear out of thin air…cells make new cells by dividing!)

1. Schleiden (circa 1838)All plants are made of cells!

Onion skin cells

2. SchwannAll animals are made of

cells!

Human red blood cells

3. Virchow

All cells come from

pre-existing cells!

Microscopic (mostly) Measured in microns µm (micrometers).

A µm is one millionth of a meter = 10-9 m = one thousandth of 1 mm.

Form follows function! - a cell’s function influences its physical features - cells vary in shape, size, and internal organization

Both Have:CytoplasmRibosomesPlasma MembraneWith Plants: Cell WallWith (some) Animals: Flagella

Prokaryotes do not have a nucleus! Eukaryotes are more complex Eukaryotes are larger

From Greek words…EU means TRUE. PRO means BEFORE. KARYON means NUCLEUS.

Eukaryote = TRUE NUCLEUS; Prokaryote = BEFORE NUCLEUS.

All cells have DNA, in eukaryotes it is stored in the nucleus.

Prokaryotes don’t have a nucleus, and it floats around in the cytoplasm in an area called the nucleoid.

Only eukaryotes have membrane-bound organelles.

Statement Prokaryotic

Eukaryotic

1. Have a nucleus

2. Have membrane-bound organelles3. Contain genetic material (DNA)4. Can be single or multi-celled

5. Can only be single-celled.

6. Have a plasma membrane and cytoplasm

Cells make up tissues which make up organs which make up organ systems which make up organisms

We can also take it back to the atomic level..

Eukaryotic cells Plant Cells Bozeman Science – the cell