Discovering Cells
Lesson 1 – TB pages 122-129
What are cells?
• Cells are the basic units of structure and
function in living things.
• All living things are made of cells.
Cells and Structure
• When you describe what an object is made of
and how its parts are put together, then you
are describing the structure of an object.
• When you describe what a living thing is made
of and how its cells are put together, then you
are describing the structure of a living thing.
Cells and Function
• An organism’s functions are the processes that
enable it to live, grow, and reproduce.
• Cells are involved in all functions of the
organism. They work together.
• Each cell carries out the basic functions that
let it live, grow, and reproduce. Those
functions include obtaining oxygen, food, and
water and getting rid of wastes.
What Scientists made key discoveries
in the early study of cells?
Robert Hooke
• In 1663, he observed a slice of cork with his
microscope and discovered cells. He called
them “small rooms.”
Anton van Leeuwenhoek
• Around 1674, he discovered onecelled organisms with his
microscope. He called them
“animalcules.”
Matthias Schleiden
• In 1838, he concluded that all plants are made
of cells.
Theodor Schwann
• 1n 1839, he concluded that all animals are
made of cells.
• He discovered the differences between animal
and plant cells.
Rudolph Virchow
• In 1855, he proposed that new cells are
formed only from cells that already exist.
The Cell Theory
How many years did it take for the cell theory to
unfold? Why did it take so long?
Why is it a scientific theory and not a scientific law?
Light Microscopes
• focus light through lenses to produce a
magnified image
Compound Microscope
• focuses light through a lens to produce an image
• magnifies the image using two lenses at once
• can magnify an object more than a single lens can
• This compound microscope has a 10x lens in the
eyepiece. The revolving nosepiece holds three different
Lenses: 4x, 10x, and 40x.
Calculate the three total magnification possible for the
microscope.
10 x 4= 40x
10 x 10 = 100x
10 x 40 = 400x
Electron Microscopes
• use beams of electrons
instead of light
• can see objects that are
too small to be seen with
light microscopes
• Have higher
magnification and better
resolution