The beginning of the Cell

Mr. Fox’s 7th Grade Science Class

Cells

• The cell is the smallest form of life.– Carries out all the life processes– Nothing smaller is considered to be alive

Robert Hooke

Robert Hooke

• English scientist and engineer• Created a compound light microscope• Looked at cork cells in 1663• Discovered and called it a cell

Anton von Leeuwenhoek

Anton von Leeuwenhoek

• Dutch businessmen• Used a simple microscope to look at pond

water in 1683• First to see living cells and bacteria in the

water.

The Cell Theory

• 200 YEARS AFTER Hooke and Leeuwenhoek• Scientists started to question what makes all

living things up

Matthias SchleidenGerman Scientist1838Worked with plants

Said: “ALL PLANTS are made of cells”

Theodore SchwannGerman Scientist

1 year After Schleiden 1839Worked with animals

Said: “ALL Animals are made of CELLS!”

Rudolf VirchowGerman Scientist1855Thought people were silly for believing in spontaneous generation.

Spontaneous generation – life coming into being from things that were once living but are no more.

Proved spontaneous generation WRONG!

Said: “ALL Cells come from preexisting cells!”

All cells come from living cells.

The Cell Theory

• Scientists had to think of how to make it easier to explain their new cell theory.

The Cell Theory

• 1. All cells are the basic unit of structure and function of all living things

• 2. All living things are made of cells• 3. All cells come from other living cells

Studying Cells

• In biology we study cells by using a microscope.

• Microscope – a device designed to magnify small things many times larger!

Microscope

Parts of the Microscope

• Ocular Lens – (eyepiece) allows you to see into the microscope, it also magnifies a small amount.

• Body tube – the part you look through.• Arm – connects the body tube to the base of

the microscope.• Base – the bottom of the microscope.

Parts of the Microscope 2

• Stage – place where you put your slide. • Stage Clips – keep the slide secure in place.• Light Source – where the light comes from

under the stage. • Diaphragm – controls the amount of light

going through the stage.

Parts of a Microscope 3

• Revolving nose piece – controls what objective lens you are looking through.

• Objective Lens – lens that greatly magnifies what you are looking at. Can come in many different powers on a microscope.

• Coarse adjustment Knob – adjusts the focus of the microscope.

• Fine Adjustment Knob – fine tunes the focus to make things clearer.

Microscope Rules

• Carry the microscope with one hand under the base and the other on the arm close into your body.

• Never use the coarse adjustment knob when using high power

• When putting the microscope away, make sure its on the low power objective lens and the stage is put all the way down or the body tube all the way up!

Total Magnification

• Microscopes have 2 lens that magnify images.

• Ocular Lens x Objective lens = total magnification

eyepiece = 5x Objective lens = 25x

5 x 25 = 125x total magnification

Other Microscopes

• Transmission electron microscope – magnifies up to 500,000 times!(dead things only)

• Scanning electron microscope – magnifies up to 150,000 times!

• Scanning Tunneling Microscope – magnifies up to 1,000,000!!!!!!!!!

Pictures