History of the CellHistory of the Cell

How are these cells the same and How are these cells the same and how are they different?how are they different?

What is a cell?What is a cell?A cell is the A cell is the basic unit of lifebasic unit of life..

A cell is a A cell is a structurestructure within a living thing that has within a living thing that has a a boundary surrounding boundary surrounding the material inside.the material inside.

How small is a cell?How small is a cell?

How were cells discovered?How were cells discovered?

Scientists were curious about Scientists were curious about what living things were made what living things were made of.of.

So they created So they created microscopesmicroscopes to take a closer look at living to take a closer look at living things.things.

Who were the main people involved Who were the main people involved in the discovery of cells?in the discovery of cells?

Anton van LeeuwenhookAnton van Leeuwenhook

Robert HookeRobert Hooke

Robert BrownRobert Brown

Matthias SchleidenMatthias Schleiden

Theodor ScwannTheodor Scwann

Rudolf VirchowRudolf Virchow

Anton von LeeuwenhoekAnton von Leeuwenhoek

1600s.1600s.First to see and describe cells.First to see and describe cells.Used a Used a simple microscope simple microscope (one lens).(one lens).Looked at tiny living organisms in a Looked at tiny living organisms in a drop of drop of pond waterpond water (“wee beasties”). (“wee beasties”).

Robert HookeRobert Hooke

1665.1665.First to use the term, First to use the term, ““cellscells.”.”Used a Used a compound compound microscope microscope (2 lenses).(2 lenses).Looked at a slice of Looked at a slice of corkcork (dead cells).(dead cells).Noted for seeing, Noted for seeing, describing, and explaining.describing, and explaining.

Robert BrownRobert Brown

1831.1831.

First to identify the First to identify the nucleusnucleus..

Realized that nucleus was doing something Realized that nucleus was doing something important. important.

Matthias SchleidenMatthias Schleiden

1838.1838.

First to conclude that all First to conclude that all plantsplants are made of cells. are made of cells.

Theodor SchwannTheodor Schwann

1839.1839.First to conclude that all First to conclude that all animalsanimals are made of are made of cells.cells.

Rudolf VirchowRudolf Virchow

1855.1855.

Cells reproduceCells reproduce: that : that is where new cells is where new cells come from.come from.

““When a cell exists, When a cell exists, there must have been there must have been a pre-existing cell…”a pre-existing cell…”

What is the Cell Theory?What is the Cell Theory?

1. 1. All living things are made of cells. All living things are made of cells. (Schleiden = plants, Schwann = animals)(Schleiden = plants, Schwann = animals)

2. Cells are the 2. Cells are the basic units of structure and basic units of structure and functionfunction in living things. in living things.

3. New cells are produced from 3. New cells are produced from existing existing cells. cells.

(Virchow)(Virchow)

Prokaryotes and EukaryotesProkaryotes and Eukaryotes

Word originsWord origins

eu….. means ‘true’eu….. means ‘true’

pro…. Means ‘earlier than’pro…. Means ‘earlier than’

karyon….. means ‘kernel’karyon….. means ‘kernel’

organelle…means ‘mini-organ’organelle…means ‘mini-organ’

Cells Come in a Variety of Shapes Cells Come in a Variety of Shapes and Sizesand Sizes

Smallest= mycoplasma bacteria (0.2 µm in

diameter)

Largest = Chaos chaos amoeba (1000 µm in

diameter)

Most cells = 5 to 50 µm in diameter

ProkaryotesProkaryotes EukaryotesEukaryotes

SizeSize

Usually Usually smaller and smaller and

simplersimplerUsually larger and Usually larger and

more complexmore complex

NucleusNucleus AbsentAbsent PresentPresent

Genetic Genetic MaterialMaterial

Not in Not in nucleusnucleus

In nucleus (separate In nucleus (separate from rest of cell)from rest of cell)

ExampleExample BacteriaBacteriaPlants, animals, Plants, animals,

fungi, protistsfungi, protists

4

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Prokaryotic and Eukaryotic Cells

Prokaryotic Cell Parts: BacteriaProkaryotic Cell Parts: Bacteria