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Objectives:
• Microscopes are used correctly to observe living cells.
Cells •basic units of structure and
function in living things. • (all living things are made
of cells) •1 cm of your skin’s surface
contains 100,000 cells too tiny to see.
Structure vs. Function
• What it What it does.
Appears to look What it runs.
Like. How it is Why it is set up
Organized. The way it is.
Structure vs. Function
Structure vs. Function
Structure and Function in people
Structure vs. Function
Structure: Cells have different structures
and are made differently
Function: Because they do different
things!
FIRST SIGHTINGS OF CELLS
•Microscope—an instrument that makes small objects look larger.
FIRST SIGHTINGS OF CELLS
• The 1590 invention of microscope allowed people to look at very small objects. The microscope made it possible for people to discover and learn about cells.
• Simple microscope—contains one lens that helps to focus light
• Compound microscope—a light microscope that has more than one lens.
Robert Hooke a. One of the first people to observe cells. In 1663 Hooke
observed a small piece of cork with a compound microscope that he built. Cork is made from the bark of the cork oak tree, and is made up of cells that are no longer alive. He saw tiny “rectangular little rooms” that he called cells. He found that one centimeter of cork had over a thousand cells.
Anton van Leeuwenhoek • a Dutch businessman and amateur scientists
made his own lenses to construct a simple microscope. He looked at water from a pond and found many one-celled organisms which he called “animalcules” meaning small animals. Also looked at scrapings from teeth and was the first person to see the tiny single-celled organisms that are now called bacteria. Many people began to study cells after his findings.
• PASS Strand:Structure and Function in Living Systems
• Objectives: (What we will be talking/ learning about)
Microscopes are Used correctly to observe living cells.
Cells are the building blocks of all organisms (both plants and animals).Local extension: The cell theory states:
1. All living things are made up of cells. 2. Cells are the basic units of structure and
function in all living things. 3.Living cells come only from other living cells.
THE CELL THEORY
• Microscopes led to the discovery that all living things are made up of cells.
– Schleiden (shly-dun)—scientists who discovered that plants are made up of cells.
– Schwann—scientists who discovered that all animals are made up of cells. All living things are made up of cells.
– Virchow—(fur koh) new cells are only formed from existing cells. All cells come from other cells.
–These discoveries led to the CELL THEORY. The CELL THEORY is a widely accepted explanation of the relationship between cells and living things It states• All living things are composed of cells
• Cells are the basic unit of structure and function in living things
• All cells are produced from other cells.
How A Light Microscope Works
• Microscopes use lenses to make smaller objects look larger. Microscopes must include magnification and resolution.
Magnification—the ability to make things look larger than they are.
• Lens—the lens or lenses in a light microscope magnify an object by bending the light that passes through them.
• Convex lens—curved lens. Center is thicker than edges.
Magnification
• Compound microscopes—use more than one lens, so magnify more than simple microscopes.
• Total magnification is equal to the magnifications of the two lenses multiplied together.
Resolution—is the ability to clearly distinguish the individual parts of an
object. It helps the image look “sharper”, “more clear” or “being able to see fine
detail”
ELECTRON MICROSCOPES– Hooke, Leeuwenhoek and others all
used light microscopes.
– 1930s electron microscope was invented.
• Use a beam of electrons instead of light to examine a specimen.
• Resolution is much better than light microscopes.
• Continue to learn about the structure and function of cell
