Chapter 7:

The Microscope and Cell Theory

Try these websites for fun!

• http://learn.genetics.utah.edu/content/begin/cells/insideacell/

• http://www.sheppardsoftware.com/health/anatomy/cell/cell_game.htm

Cell Theory

• Term “cell” was coined in 1665 by Robert Hooke when he looked at a slice of dried cork.

• Cell Theory1. All living things are made

of cells.

2. Cells are the smallest “living” unit

3. All cells came from previously existing cells.

Then

Now

2 main types of cells

• Prokaryotic– Lack membrane

enclosed organelles

– Lack a nucleus– Only Unicellular– Bacteria

• Eukaryotic – Have membrane

bound organelles– Have a nucleus– Can be unicellular or

multicellular– Plant and Animal Cells– 10 Times Larger than

Prokaryote Cells.

What each cell has:• Prokaryote

– DNA– Plasma Membrane– Ribosomes– Cell Wall– Cytoplasm– Cilia/flagella

• Eukaryote– Nucleus w/ DNA– Plasma membrane– Ribosomes– Cell wall (plant)– Cytoplasm– Endoplasmic Reticulum– Mitochondria– Golgi apparatus– Large vacuole (plant)– Chloroplast (plant)– Lysosome (animal)– Cilia/flagella (animal)

Microscopes

• In the 1600’s the first microscope was invented.

• Microscopes magnify objects

• Two main types of microscopes– Compound light microscope

• Multiply lenses to find out magnification

• Magnifies about 1500 times

– Electron microscope• Uses a beam of electrons to magnify

structures• Up to 500,000 times magnified!!!!

Anton van Leeuwenhoek

Microscope parts

tube

stage clips

Light/mirror

base

diaphragm

eye piece

10x objective

40x objective

100x objective

fine adjustment

rough adjustment

stage

armnosepiece

Plasma (cell) Membrane

• Physical & chemical boundary of all cells

• A double layer called the phospholipid bilayer. – It is selectively permeable (semipermeable)

meaning only certain things are let in and out• Gate-keeper of cell

Function of Proteins in Membrane

1. Transport Proteins- move large things in and out of cell

Ribosomes • Sites of protein synthesis

– Proteins are the main product produced by the cell

• Not considered a membrane-bound organelle so they are found in prokaryotes and eukaryotes

• Control center of cell (controls all cellular activites)– Contains DNA – Contains nucleolus where

ribosomes are made

Nucleus

Nucleolus

• Located inside of the nucleus

• Contains RNA and proteins

• Makes ribosomes

Nuclear membrane/ Nuclear envelope

• The double-layered membrane enclosing the nucleus of a cell.

Endoplasmic reticulum• Transport system of cell (transports materials)

– Rough Endoplasmic reticulum (RER) has ribosomes

– Smooth Endoplasmic reticulum (SER) for lipid synthesis and storage

Golgi Apparatus• Involved in packaging and secretion of proteins

– The cellular post office– Also called golgi body

Mitochondria

• Where energy for the cell is made (ATP)

• Site of cellular respiration

Adenosine Tri Phosphate (ATP)

Lysosomes• Found in animal cells

– Digest and recycle worn out cell parts– Destroy foreign invaders

Plant cell only• Large vacuoles for storage of

water and sugars

• Cell wall made of cellulose for support and protection

• Chloroplasts– Where photosynthesis happens

(glucose is made from water, CO2, & sunlight)

– Give green color

Two organelles have their own DNA

• Mitochondria and Chloroplasts have their own DNA because they were probably once free-living bacteria that were “eaten” by a larger cell and instead of being digested, they became part of that cell as an organelle