Discovering Cells 10.2

Cells… Definition: The basic unit of structure and function of all living things. Structure: The arrangement of the parts of something complex. Ex. nucleus Function: How things work. Ex. Nucleus is like the brain of the cell…it controls it’s function. What are the functions of a cell? Get rid of wastes (CO2) Help us get oxygen Helps us take in water Helps us take in food

Robert Hooke 1663, Hooke used his microscope to observe a thin slice of cork. The bark of the cork tree is made up of cells that are no longer alive. The empty spaces in the cork looked like tiny rectangular rooms. He called the empty spaces cells which mean “small rooms”.

Anton van leeuwenhoek 1674 Leeuwenhoek built a microscope and was the first to look at drops of lake water, teeth scraping, and gums. He was surprised to find one-celled animals.

Theodor Schwann (swan) 1838 Mathias Schleiden He concluded that all plants are made of cells. Theodor Schwann (swan) 1839 He reached the same conclusion about animals. 1855 Rudolf Virchow He proposed that new cells are formed from cells that already exist. All cells come from cells.

Schleiden Schwann Virchow

Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things. All cells are produced from other cells.

Magnification Resolution Changes how you can see objects and reveals details you may not have known were there. Resolution The degree to which two separate structures that are close together can be distinguished.

Discovering Cells Resolution The images in colorful photographs actually consist of only a few ink colors in the form of dots. This circle has been enlarged to show a tiny section of a picture of a bird's wing.

A Compound Microscope This microscope has a 10x lens in the eyepiece. The revolving nosepiece holds three different lenses: 4x, 10x, and 40x. The total magnification of the microscope is: 10 X 4 = 40x 10 x10= 100x 10 x 40 = 400x Revolving nosepiece Lenses Lens Slide Stage Light rays Light source

This type of instrument, called a compound microscope, magnifies the image using two lenses at once. One lens is in the eye piece. A second lens is chosen from a group of two or three lenses on the revolving nosepiece.

Electron Microscope Electron microscopes use a beam of electrons instead of light to produce a magnified image. Electrons are tiny particles that are smaller than atoms. By using electron microscopes, scientists can obtain pictures of objects that are too small to be seen with light microscopes. Electron microscopes allow higher magnification and better resolution than light microscopes.

House fly

Cat flea

Head of maggot

Dust mite

Head of a maggot! Cat flea Common house fly House Dust Mite http://www.telegraph.co.uk/science/picture-galleries/7924099/Creepy-crawlies-Amazing-Scanning-Electron-Microscope-pictures-of-insects-and-spiders.html?image=2