Cell Theory The History Behind Cells. Where does life come from?

Cell TheoryThe History Behind Cells

Where does life come from?

Spontaneous Generation

• Spontaneous Generation: The idea that life can appear from the non-living environment

• Francesco Redi disproved this idea through his meat experiments

Spontaneous Generation

• Louis Pasteur’s Experiment

Microscope Invented• Hans & Zacharias Janssen

o Made 1st compound microscope (2 lenses)o Allowed people to see things never before

seen!

Robert Hooke 1655• Used microscope to look at oak cork• He observed “tiny little boxes”• Called structures “cells”

Review• Who named cells because they looked like “tiny

boxes”?

a. Francesco Redib. Louis Pasteurc. Robert Hooked. Albert Einstein

Anton Van Leeuwenhoek 1675

• Used a simple microscope (1 lens):o Observed blood, rainwater, sperm etc.

• Called them “animalcules” because they looked like little animals

Matthias Schleiden 1838

• German botanist• Discovered that plants are also made of cells!

Theodor Schwann 1850

• German zoologist• Viewed animal parts under microscope• Discovered animals were made of cells

Rudolph Virchow 1858• German Doctor• Concluded that all living cells come only from

other living cells

Review• Who was the first person to observe living cells?

(He called them animalcules)

a. Robert Hookeb. Francesco Redic. Anton van Leeuwenhoekd. Rudolph Virchow

Cell Theory• The work of many scientists led to the

development of the Cell Theory!

• The Cell Theory:1) All living things are made from one or more cells2) Cells are the basic unit of structure and function in living things3) All cells come only from other living cells

Review• Which is NOT part of the cell theory?

a. All living things are made of 1 or more cellsb. Cells come from non-living thingsc. Cells come only from other living cellsd. Cells are the basic unit of structure and function

Cool Jobs In Science• Molecular Biology

The Microscope

Why is it Important?• The microscope allowed scientist to observe things that

could not be seen with the naked eyeo Cells for example!

• Makes things appear larger than they really are!

How does it Work?• Microscopes use glass lenses to bend light

• This makes things appear larger or smaller depending on the shape of the lens

• Compound microscopes: have more than one lens! o This means they can magnify things even more!

Using Scale

• If 1hm = 10,000 cm

• How many centimetersis the organism in thispicture?

Comparing Powers of Magnification

We can see better details with higher the powers of magnification, but we cannot see as much of the image.

Which of these images would be viewed at a

higher power of magnification?

What’s my power?To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective.

What are the powers of magnification for each of the objectives we have on

our microscopes?

Calculating Magnification

• To find the total magnification of a compound microscope you must multiply the magnifying power of both lenses!

• Example: Lens 1 = 10X magnificationLens 2 = 50X magnification

Total magnification = 10 X 50 = 500X

Practice• Ocular Lens is 10x & Objective lens is 7x Total

Magnification?

• 10 X 7 = 70x

• Ocular Lens is 4x & Objective lens is 10x Total Magnification?

• 4 X 10 = 40x

Electron Microscopes• Today scientists can use electron microscopes to

look inside cells! • These microscopes use electrons instead of light

to magnify object even more!o Same particles that light up your television!

Parts of a Microscope

Function of Parts• Body Tube: separates eyepiece

from objective lens

• Eyepiece: contains lens that magnifies 10X

• Nosepiece: holds objectives lenses and allows rotation

Function of Parts• Objective lens (High Power): Magnifies

40X

• Objective lens (Low Power): Magnifies 10X

• Coarse Adjustment Knob: moves body tube to focus with low-power objective lens

• Fine Adjustment Knob: moves body tube to focus with high-power objective lens

Function of Parts

• Arm: supports the body tube

• Base: supports the microscope

• Stage: supports the slide being used

• Stage clip: holds the slide in place

Function of Parts• Diaphragm: controls the amount of light

that comes through the stage

• Mirror/Light Source: reflects light upward through diaphragm