Cells What is a cell Smallest unit of

Cells

What is a cell? • Smallest unit of life that can carry out all the functions of a living thing. • Various sizes and shapes • Organism (living thing) can be unicellular or multicellular

Skin Cell Root cell Plant Cell Red Blood cell Nerve Cell

Discovery of the Cell • Anton van Leeuwenhoek (1674) - looked at cells in pond water using the first microscope • Robert Hooke (1665) looked at cork and named the “cell”

• 1838 – Schleiden – all plants are made of cells • 1839 – Schwann – all animals are made of cells Therefore the basic unit of life is a cell

1855 – Virchow – all cells come from pre-existing cells His ideas led to… Modern Cell Theory • Cells are the basic units of structure and function in all life. • All organisms are made of one or more cells. • All cells come from pre-existing cells.

A cell is made of… • Organelles – cell parts – Organelles are made of molecules • Molecules are made of atoms

Levels of Organization (CTOSO) • cell – basic unit of structure of all life • tissue - groups of similar cells • organs - groups of tissues working together • systems - groups of organs working together • Organism – groups of organ systems working together

Types of Cells Prokaryotic • Simple cell • No membrane bound organelles • DNA not contained in nucleus • Small cells • Ex – bacteria • Prokaryotic – Simple cell – No membrane-bound organelles – DNA not contained in nucleus – Small cells – Ex - bacteria

Types of Cells • Eukaryotic – Complex cell – Membrane-bound organelles – DNA contained in nucleus – Larger cells – Ex – most other organisms