The Microscope And the cell theory

Robert Hooke (1665) First discovered cells He looked at a slice of cork under a “primitive” microscope

The cells looked like honeycomb shaped structures Hooke used the word “cell” to describe those shapes

Anton van Leeuwenhoek Observed living blood cells, and bacteria a few years later Leeuwenhoek is called the “father of microscopy”

A few years later, Robert Brown , looked at plant cells and described a dark sphere at their center, the nucleus

Cell Theory 1) All living things are composed of cells. 2) Cells are the smallest unit of life. 3) All cells come from pre-existing cells.

Brain Pop Microscopes Cell Structure

Compound Microscopes

An important development to microscopes was adding the second lens The eye piece (occular lens) magnifies the image 10x By adding a second lens that also magnifies by 10x the total magnification becomes 100x (10 x 10) By how much is an object magnified when viewing it under high power (40 x)?

Transmission Electron Microscopes

Today TEMs can magnify objects by 2 000 000 times Instead of light, TEMs use beams of electrons to magnify images TEM’s have two limitations 1. They can’t magnify specimens that contain many layers of cells 2. They can only magnify dead cells

Scanning Electron Microscopes

Can magnify thick specimens Provide a 3-D image Limitations Cannot magnify as much as TEMs Resolution (focus) is not as good as TEMs

Proper Use of a Microscope Always carry with one hand on the arm and one hand on the base Always begin on low power Never use coarse adjustment on high power

Bacteria Bacteria, Germs and viruses are some things that we can use microscopes to investigate Bacteria are one celled microorganism They can be beneficial- yogurt They can be harmful- tetanus and pneumonia Bacteria

Cell City- Project From your knowledge of cell organelles and the descriptions on the worksheet, match up the cells that do the correct function. Today you just have to correctly match up the worksheet Tomorrow we will be creating “Cell City Maps” on Art Paper This will help you remember the different parts of each organelle Two people to a group Bring Markers and Pencil Crayons !