The Discovery of CellsThe invention of the microscope led to the first

observations of cells.

Anton Van Leeuwenhoek (1632-1723) is considered the “father of microscopy.

• Robert Hooke (1635-1703) observed cork under a microscope.

• The tiny chambers which made up the cork reminded him of the rooms in a monastery.

• These rooms were called cells.

How big is a cell?

• The smallest cells are only about

0.2 micrometers wide! ( 0.0002mm)

Larger cells such as Ameba can be 1000 micrometers.

Or, even larger…the yolks of bird eggs!

Average cell size is only about 5-50 micrometers.

(0.005 mm - 0.05mm)

• Cells must carry out 5 essential functions to survive

• These processes include• Obtaining Energy (intake and storage of nutrients )

• Growth

• Waste removal

• Reproduction

• Response to stimuli

The Cell Theory

• There are 3 main parts to the cell theory:1. All living things are made up of one or more cells

2. The cell is the basic unit of life

3. All living cells come from pre-existing cells

Prokaryote vs Eukaryote

Types of Cells

Prokaryotic Cells

• First cell type on earth

• Cell type of Bacteria and Archaea

• No membrane bound nucleus

• Nucleoid = region of DNA concentration

• Organelles not bound by membranes

Eukaryotic Cells• Nucleus bound by membrane

• Include fungi, protists, plant, and animal cells

• Possess many organelles

Prokaryote/Eukaryote Handout

Endosymbiotic Theory

Variation

• Cells come in numerous shapes and sizes. Their shape is usually somehow related to their function.

• Some organisms like plankton, amoeba and bacteria are composed of a single cell.

• Other, more complex organisms, are composed of huge numbers of different cells. Humans are made up of about 300 trillion cells.

Blood Cells(Red, Platelet and White)

Macrophage killing bacteria

Nerve Cell

Human Cheek Cell

Elodea (plant) Cells

Bacteria Cells

Sperm and Egg Cells

Paramecium(single celled organism)

Amoeba(single celled organism)

Cell Parts and Functions

• Cells are composed of a number of parts each with specific functions.

• Some of the internal parts of the cell are called “organelles”.

• An organelle is defined as a membrane-bound compartment in a cell.

The Cell Membrane

• “The gatekeeper of the cell”

• A thin, outer covering of the cell.

• Controls what goes in and out of cell.

Cytoplasm

• Jelly-like fluid in the cell.

• Suspends the cell’s organelles.

• Composed mostly of water.

The Nucleus

• The “control center” of the cell.

• Directs all cellular activities including movement, growth and other life functions.

• Location of the DNA (the genetic material).

Vacuoles

• Large, membrane bound storage structures.

• In plant cells vacuoles are extremely large and also help to support the plant.

• Called VESICLES in animal cells.

The Cell Wall

• Present around plant cells ONLY. (And some bacteria.)

• Protects and supports plant cell.

Chloroplast

• Found ONLY in plant cells.

• Location of PHOTOSYNTHESIS(the transformation of light energy into chemical energy).

Centrioles

• Centrioles are ONLYpresent in animal cells.

• Centrioles aid in animal cell division.

Mitochondria

• Mitochondria are the powerhouse of the cell.

• They are the site of cellular respiration which makes useable energy for cells.

Ribosomes

• The organelle where proteins are assembled.

• Often located on the endoplasmic reticulum.

Rough Endoplasmic Reticulum

• Ribosomes attach to make proteins.

• Packages new proteins.

Smooth Endoplasmic Reticulum

• Produces certain chemicals in cells.

• Produce vesicles which contain newly produced proteins.

Golgi Apparatus

• Modifies, stores, packages and distributes proteins.

• Forms vesicles.

• Time to work on your visual dictionary