PACKET 4: Introduction to Eukaryotic Cells http://www.thetech.org/genetics/

I. Discoveries: By using lenses and primitive microscopes, early scientists discovered that all living things are made up of cells (1600-1850’s). Names to identify with microscopes & the discovery of cells: Hooke –He was given credit for naming the cell after looking at the cell walls of dead plant cells (cork). Leeuwenhoek–He used the microscope to look at tiny living organisms in pond water Many give him credit for inventing the microscope. Brown–discovered that most cells had a common dark structure in the middle (which we now call the nucleus). Scheliden–stated that all plants are made of cells. Schwann–discovered that all animals are also made of cells. Virchow–concluded that all cells come from the division of pre-existing cells.

All living things are composed of cells (1 or more) These discoveries were put together into one central idea called the cell theory, which states: All living things are composed of cells (1 or more) Cells are the basic unit of structure and function of an organism. All cells come from pre-existing cells.

II. Hierarchy of Life: atoms* combine together to make  compounds* combine together to make  organelles* combine together to make  cells combine together to make  tissues may combine together to make  organs may combine together to make  organ systems may combine together to make  organism *Atoms and compounds are not living, but must be combined to form a living cell or organism of many cells, such as a human.

Prokaryotic Cells are very simple All cells can be divided into one of two categories based upon their complexity: Prokaryotic Cells are very simple Eukaryotic Cells are complex

Prokaryotic Cells are very simple Do not have a nucleus … but they still have DNA Do not have membrane bound organelles Usually small and unicellular (meaning they are made up of a single cell) Example: Bacteria

Eukaryotic Cells are complex Have a nucleus (it holds & protects the DNA) Have membrane bound organelles Can be both unicellular and multicellular (are made of many cells). Example: Cells of Plants or Animals

DNA (genetic material) Despite the different size and shape of cells, there are certain structures that are common to all cells. Cell membrane *add ribosomes to this list Cytoplasm DNA (genetic material)