What are the parts of the microscope?

What’s the total magnification? Eyepiece Objective lens Total Magnification 10x 40x 5x 20x

A little microscope history… During the 1st century AD (year 100), glass had been invented and the Romans were looking through the glass and testing it. They experimented with different shapes of clear glass and one of their samples was thick in the middle and thin on the edges. They discovered that if you held one of these “lenses” over an object, the object would look larger.

Sometime about the year 1590, two Dutch spectacle makers, Zaccharias Janssen and his father Hans started experimenting with these lenses. They put several lenses in a tube and made a very important discovery. The object near the end of the tube appeared to be greatly enlarged, much larger than any simple magnifying glass could achieve by itself! They had just invented the compound microscope (which is a microscope that uses two or more lenses). 

Discovery of Cells

We haven’t always known about cells Because they are so small, cells weren’t discovered until microscopes were invented in the mid-1600s

Important people: Robert Hooke – 1st person to describe cells In 1665 he built a microscope British scientist

Robert Hooke – looked at cork cells He called each of the little boxes “cells”

Important people: Anton van Leeuwenhoek – looked at bacteria and blood cells. Dutch fabric store owner in 1673

Important people: Matthias Schleiden – said all plants are made of cells. German botanist in 1838

Important people: Theodor Schwann – said all animal tissues are made of cells. German scientist that studied animals

Important people: Rudolf Virchow – said all cells could only come from other cells. German doctor in 1858

Remembering the 5 Scientists Think of a piece of cork on a hook Robert Hooke Anton van Leeuwenhoek Matthias Schleiden Theodor Schwann Rudolf Virchow Think of a “blood van” leaving Think of a slide – it’s green because plants are green A swan is an animal – he looked at animal cells Think of Rudolph the reindeer making copies of himself

The Cell Theory The ideas of Schleiden, Schwann, and Virchow make up what is now called the cell theory.

The Cell Theory 1. All organisms are made of one or more cells 2. The cell is the basic unit of all living things 3. All cells come from other cells

Spontaneous Generation States that living organisms are created from non-living matter This theory was believed back in Aristotle’s time (4th Century BC)

Spontaneous Generation Cont. It was common “knowledge” that simple organisms like worms, beetles, frogs, and salamanders could come from dust, mud, etc., and food left out, quickly “swarmed” with life.

Examples Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times. Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs

Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around. Conclusion: It was obvious to them that the mice came from the moldy grain.

Observation: If meat was left out usually over time it would spoil and maggots would begin to grow and develop. Many people who believed in spontaneous generation thought that raw meat produced maggots. Conclusion: Therefore, several people widely held that maggots arose spontaneously in rotting meat

They didn’t realize that there were flies who laid eggs which led to maggots After testing this theory it was concluded that only flies could produce other flies!

Louis Pasteur The theory of spontaneous generation was finally laid to rest in 1859 by the young French chemist, Louis Pasteur. He boiled meat broth in a flask, heated the neck of the flask in a flame until it became pliable, and bent it into the shape of an S. Air could enter the flask, but airborne microorganisms could not - they would settle by gravity in the neck.

Louis Pasteur Cont. As Pasteur had expected, no microorganisms grew. When Pasteur tilted the flask so that the broth reached the lowest point in the neck, where any airborne particles would have settled, the broth rapidly became cloudy with life. Pasteur had both refuted the theory of spontaneous generation and convincingly demonstrated that microorganisms are everywhere - even in the air.

Louis Pasteur

Some book time Pg 60-61, use the Biology book to fill out your notes on Advancing the microscope

Light microscopes – Advantages – Disadvantages -

Electron microscopes – Advantages – Disadvantages -

Transmission Electron Microscopes (TEM)– Scanning Electron Microscope (SEM) –

Dissecting Microscope

Images seen using an electron microscope

Mosquito head Magnification: X 200 The mosquito's head is mostly eye. The eyes of most insects are compound eyes, made up of many tiny lenses. Each lens sees a slightly different picture, making up a mosaic of the object it is looking at. This type of vision is very efficient at noticing very slight motions such as another insect trying to sneak up on it

Magnification: X 300 Foot of a House Fly Flies use their feet for many purposes. The claws can grab to hold on. The small hairs will adhere to smooth surfaces through surface tension. Other hairs are sensory organs, allowing flies to taste with their feet.

Porcupine quill Magnification: X 50 Porcupine quills are sharp as needles. Unlike needles, quills have backwards facing barbs that catch on the skin making them difficult to extract.

Dentist Drill Magnification: X 50 The dentist drill is covered with tiny diamond chips. Diamonds are the hardest substance known and will easily wear away tooth particles as the drill spins at high speeds.

Toilet paper Magnification: X 500 The long, thin fibers you see here are really elongated cells of the pine tree. The trees are cut down, chipped up and pounded to separate the fibers from the rest of the tree material.

Staple through paper Magnification: X 35 Common everyday items take on a new dimension at high magnification. In this photo, a staple is seen where it ripped through the fibers of a yellow sticky note paper.

Scratch and Sniff paper Magnification: X 1,000 These tiny glass capsules contain a liquid scent and are glued onto paper. When the paper is scratched, some of the capsules are ruptured and the scent is released.

Rice Leaf Magnification: X 750 Many grasses feel rough to the touch. A close-up of this rice leaf shows its bumpy texture.

Mascara Brush Magnification: X 35 The bristles of this mascara brush are covered with dried mascara and flakes of skin.

Bacteria living on skin

Ice cream under electron microscope (showing fat globules and ice crystals)