Eukaryotes & Prokaryotes

• Plant and animal cells are both eukaryotic cells
• Eukaryotic cells vary in size, usually between 10 and 100 µm
• A defining feature of eukaryotic cells is that their genetic material (DNA) is enclosed within a nucleus
• there are two distinct types of cell – eukaryotic and prokaryotic

  
• Animal and plant cells are both eukaryotic cells as their genetic material is packaged in a nucleus

  
• Bacterial cells are a type of prokaryotic cell
• A defining feature of prokaryotic cells is that their genetic material is not enclosed within a nucleus, it is found as a single loop of DNA within the cytoplasm
• • Additional smaller, circular pieces of DNA called plasmids may also be present
• • The cell membranes of all prokaryotic cells are surrounded by a cell wall (usually made from a substance called peptidoglycan)
• • Prokaryotic cells are much smaller in comparison to eukaryotic cells, with many measuring ~ 1 µm in size
• Prokaryotic cells do not have a nucleus, and are much smaller than eukaryotic cells

  
• Prokaryotic cells table

  
• • Cells are very small and require a microscope to be seen
• • Scientists measure the size of cells in micrometers (µm)
• • 1 µm is equivalent to 0.001 mm, or 1 x 10-3 mm (or alternatively 1 millionth of a metre,  1 x 10-6 mm)
• Need to know how to convert

  
• many subcellular structures in eukaryotic cells are the same size as or bigger than prokaryotic cells!

  
• • Differences in size can be described as differences in order of magnitude, essentially the difference in size calculated by a factor of 10
• Size of cells table