Cell Theory The History Behind Cells Where does

Cell Theory The 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 1 st 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. b. c. d. Francesco Redi Louis Pasteur Robert Hooke 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. b. c. d. Robert Hooke Francesco Redi Anton van Leeuwenhoek 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 cells 2) Cells are the basic unit of structure and function in living things 3) All cells come only from other living cells

Review • Which is NOT part of the cell theory? a. b. c. d. All living things are made of 1 or more cells Cells come from non-living things Cells come only from other living cells 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 eye o 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 1 hm = 10, 000 cm • How many centimeters is the organism in this picture?

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 = 10 X magnification Lens 2 = 50 X magnification Total magnification = 10 X 50 = 500 X

Practice • Ocular Lens is 10 x & Objective lens is 7 x Total Magnification? • 10 X 7 = 70 x • Ocular Lens is 4 x & Objective lens is 10 x Total Magnification? • 4 X 10 = 40 x

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 10 X • Nosepiece: holds objectives lenses and allows rotation

Function of Parts • Objective lens (High Power): Magnifies 40 X • Objective lens (Low Power): Magnifies 10 X • 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