Discovering Cells 7 th grade science

What do you think a fungus, a tree, and a red newt have in common?

they are all living things, or organisms, and like all organisms, they are made of cells

Cells are the basic unit of structure and function in living things! Cells form the parts of an organism and carry out all of the organism ’ s processes or functions

Cells and Structure – the structure of living things are determined by the amazing variety of ways that cells are put together Ex: a red newt ’ s cells form a body with a head and four legs. Meanwhile, a tree consists of cells arranged to form a high trunk and leafy branches

Cells and Function – an organism ’ s functions are the process that enables it to stay live and reproduce Ex: some functions include obtaining oxygen, getting rid of wastes, obtaining food and growing

Cells are so small that until the late 1600s, no one knew cells even existed because there was no way to see them! In around 1590, the invention of the microscope made it possible for people to discover and learn about cells

Microscope – is an instrument that makes small objects look larger – some microscopes do this by using a lens to focus

For microscopes to be useful, it must combine two important properties – magnification and resolution Magnification – is the ability to make things look larger than they really are – lenses in light microscopes magnify an object by bending the light that passes through them **A lens with a curved shape in the middle is called a convex lends** Resolution – is the ability to clearly distinguish the individual parts of an object – basically, another term for sharpness of an image

There are many different types of microscopes! We use either Compound Microscopes or Electron Microscopes!

Compound microscopes use light to pass through the specimen. Meanwhile, an electron microscope uses a beam of electrons instead of light to produce a magnified image! Modern Compound Light Microscope – can magnify a specimen up to 1,000 times Transmission Electron Microscope (TEM) – sends electrons through a very thinly sliced specimen – can magnify a specimen up to 500,000 times

Robert Hooke – an English scientist, who was one of the first people to observe cellsHooke built his own compound microscope and used it to observe the structure of a cork – cork, which is the bark of cork oak tree, is made up of cells that aren ’ t alive cork

Anton van Leeuwenhoek – a Dutch businessman, who built microscopes in his spare time, looked at: Drops of lake water Scrapings from teeth and gums Water from rain gutters

surprised to find a variety of one-celled organisms and noted that many of these organisms moved – some whirled, some hopped and some shot through the water like fish

Three German scientists, Matthias Schleiden, Theodor Schwann and Rudolf Virchow, contributed to what we know today as Cell Theory Schleiden concluded that all plants are made of cells Schwann concluded that all animals are also made up of cells. Then stating that all living things are made up of cells. Virchow proposed that new cells are formed from cells that already exist – “ all cells come from cells ”

Schleiden concluded that all plants are made of cells

Schwann concluded that all animals are also made up of cells. Then stating that all living things are made up of cells.

Virchow proposed that new cells are formed from cells that already exist – “ all cells come from cells ”

Cell Theory States: 1.All living things are composed of cells 2.Cells are the basic unit of structure and function in living things 3.All cells are produced from other cells