LESSON 1: Prokaryotic and Eukaryotic Cells LEARNING OUTCOMES By the end of the lesson, you should be able to:  Describe the structure of prokaryotic and eukaryotic and the differences between them.  Identify structures in prokaryotic and eukaryotic cells in light micrographs.  Describe specialised parts of cells and their functions.

Cell Theory  The cell theory states: 1. All living organisms are made up of cells and their products. 2. All cells come from the division of pre- existing cells. 3. The cell is the smallest living organisational unit.

Cell Types  There are 2 main types of cells – prokaryotes and eukaryotes.  All cell types have specialised features that enable them to fulfill their functions efficiently.

Prokaryotes  Are small in size.  Lack membrane bound organelles.  Do not have a distinct nucleus.  Contain a circular DNA chromosome found in the nucleoid.  The cytoplasm contains ribosomes but no other organelles (the presence of the ribosomes allows prokaryotes to synthesise proteins).  Prokaryotic cells include bacteria and cyanobacteria.

Eukaryotes  Are larger in size.  Have membrane bound organelles.  DNA is present as linear chromosomes in a membrane bound nucleus.  Contain a variety of organelles in the cytoplasm each with a particular function.  Eukaryotic cells include animal, plant, fungi and protista cells.  To make it easier we think in terms of “typical” cells (although none really are). We also split eukaryotic cells into 2 smaller groups – plant cells and animal cells.

The differences between plant and animal cells Plant cells:  Have a large central vacuole.  Have a thick cellulose cell wall outside the plasma membrane.  Lack centrioles.  Have chloroplasts in cells where photosynthesis occurs (not all plant cells have chloroplasts) Animal cells:  Have smaller vacuoles (usually referred to as vesicles).  Lack a cell wall outside the plasma membrane.  Have centrioles.  Do not have chloroplasts.