Introduction to Cells Biology A/Cells

The Discovery Cells were first discovered in 1665 when Robert Hooke observed a slice of cork under a microscope. Hooke thought the small divisions looked like the monastery cells that monks lived in.

The Discovery Anton van Leeuwenhoek was the first to observe micro- organisms in 1674, when he observed a drop of water under a microscope.

The Discovery Continues… The combined work of a number of other scientists finally led to the development of the cell theory.

The Cell Theory All living things are made of cells. Cells are the basic units of structure and function in living things. New cells are only produced by other cells.

Micro-organisms We will discuss 3 main types of micro-organisms: 1. Viruses 2. Bacteria 3. Protists

Bacteria Bacteria are microscopic, single-celled organisms. Bacteria are prokaryotes which means that their DNA is not contained inside the protective coating of a nucleus.

Viruses Viruses are the simplest and smallest micro-organisms. They contain a small amount of DNA (genetic material) and a protective coat called a capsid. Viruses reproduce by attaching to another cell and overriding normal cell functioning so that the cell produces new viruses.

2 Categories of Cells Prokaryotic Cells Eukaryotic Cells

Prokaryotic Cells Do not contain a nucleus Are smaller and simpler than eukaryotic cells Example: Bacteria

Eukaryotic Cells Have a nucleus Are larger and more complex than prokaryotic cells Contain specialized structures called organelles Examples: Plant cells Animal cells

Protists Protists are generally larger than viruses and bacteria, but they are still microscopic. Protists are eukaryotes, which means their DNA is contained in a protective nucleus.