CELLSSmallest unit

of life that can carry out

all the functions of an organism.

History of the Cell:• 1665 – Robert Hooke discovered and described the fundamental unit of all living things (cells) by using thin slices of cork.• He gave the tiny chambers the name “cell” because it reminded him of a monastery's tiny room which were known as cells.

History of the Cell:

• 1674 – Anton Van Leeuwenhoek (“Father of Microbiology”) was the first man to witness a live cell under a microscope.

• He made many different types of single lens microscopes that could magnify up to 300 X.

• When observing pond water, he discovered tiny organisms he called "animalcules.”

History of the Cell:

History of the Cell:

• 1838: Matthias Schleiden (Botanist) concluded that all plants are made out of cells.

History of the Cell:• 1839: Theodor Schwann (Zoologist) concluded

that ALL organisms including animals are made up of cells.

History of the Cell:

• 1855: Rudolph Virchow (Doctor) – proposed that all cells arise from existing cells.– Until 1855: Schleiden and Schwann believed that cells

might “crystallize out” from fluids.

These discoveries, confirmed by other biologists, are summarized in the CELL

THEORY

What is the Cell Theory?A fundamental concept in biology that

states:

1. Cells are the basic units of life (Hooke)2. All organisms are made of cells

(Schleiden &Schwann)3. All cells come from existing (other) cells

(Virchow)

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Part of the Microscope

Parts of the MicroscopeA. Occular (eye

piece)B. Body TubeC.Revolving

NosepieceD.Objective

LensesE. StageF. Diaphragm

(controls amount of light)

G. Light sourceH. BaseI. Fine Adjustment knobJ. Coarse Adjustment KnobK. Stage Clips (holds slides)L. Arm

Parts of the Microscope

Carrying a Microscope

Magnification increases the apparent size of a specimen when you view it through the microscope.

Calculating Magnification

Magnification of X occular lens magnification

objective lens

Since microscopes magnify cells we have a new unit of measurement.

These new units are called microns.

1mm = 1000 µm 1 = 1 µm1000

We can use microscopes to estimate the size of cells we are looking at.

a)if the field of view = 1mm

then onion cells are

______________ mm

or ______________(µm) in length

1mm (1000 µm)

Field of view

Onion cell

0.5

500 microns

Example

b)if the field of view = 0.5mm or 500µm

then these cheek cells would be

mm or ______________ µm in length

0.5 mm (500 µm)Human cheek cell

500

5100