Download Cell theory What makes a living thing different? All living things have

Cell theory
What makes a living thing different?
All living things have the following characteristics:
Organization (organism’s body must be organized in a way that enables it to meet its needs)
Ability to develop and grow
Ability to respond to the environment
Ability to reproduce
Needs of life
We need energy, materials, and living space
We need energy to move, to sleep, to breathe, and think
Energy used by almost everything living thing on Earth comes from the Sun
Some capture it directly (plants and some bacteria)
Food not only provides our source of energy, but also the materials necessary for growth and reproduction
Without these basics needs, we die
All living things are made of cells
The cell is the smallest unit of a living thing
Some are made of a single cell or unicellular (usually to small to see)
Some are made of many different cells that work together or multicellular
Multicellular organisms are more complex and have specialized cells that perform specific functions
We have muscle cells which allow us to move and nerve cells which transmit messages throughout our bodies
Seeing cells
Trying to see cells is like trying to see the individual photos in a mosaic across the room.
As you move in closer, the images become easier to see
http://www.mazaika.com/33_gigapixel_photo_mosaic_face_britain.html
Microscope led to the discovery of cells
Most cells are too small to see without the aid of a microscope
A microscope is an instrument which makes an object appear bigger than it is
In the 1660’s, Robert Hooke began using microscopes to look at all sorts of materials
Anton van Leeuwenhoek took up similar work in the 1670’s
Hooke gave cells their name while looking at cork he saw compartments that looked like tiny empty rooms or cells. Empty
because they were dead
Leeuwenhoek observed living cells in pond water
Cells come from other cells
People started to wonder if living things had cells
More and more scientists observed more and more living things and kept finding more cells
They started wondering where do these cells come from?
By the 1850’s scientists discovered that cells divide
This led them to the three components of cell theory:
Every living thing is made of one or more cells
Cells carry out the functions needed to support life
Cells come only from other living cells
Robert Hooke
Contributions:
He observed pieces of cork from the bark of a cork tree under the microscope.
1665- His observations led him to coin the word “cell.”
“Cell”- means little rooms in Latin
He compared the small boxes to the small rooms that monks lived in.
Anton van Leeuwenhoek
Discoveries:
1673: He looked at pond scum under the microscope and discovered small organisms he called
animalcules or little animals (Protists)
- 1676: discovered
bacteria
Matthias Schleiden
1838- Discovered that all plants were made of cells
Theodor Schwann
1839- Concluded that all animals are made of cells.
Rudolph Virchow
1855- Discovered that all living cells come only from other living cells.
Cell theory and its significance
Louis Pasteur lived in the 1800s when there was no refrigeration at home
Many people would die from diseases from spoiled, rotting foods
Pasteur observed that milk turned sour because of large numbers of single-celled organisms called bacteria
He developed a process known as pasteurization in which heat is used to kill bacteria
This discovery also led Pasteur to question if bacteria can make milk go bad, then can it also cause humans and animals to
get sick?
Bacteria and spontaneous generation
Pasteur found bacteria everywhere. Air, soil, and water.
He found bacteria in blood of animals and people that were sick
If he could understand bacteria, then he could understand how they make people sick
His work led to the first animal vaccinations for cholera and anthrax and treatment for rabies
Some scientists believed that bacteria grew from nonliving things spontaneously.
Pasteur proved them wrong with his famous experiment
http://ed.ted.com/lessons/the-wacky-history-of-cell-theory