Biology Unit 1

Prokaryotic and Eukaryotic Cells:

• Prokaryotic have no nucleus.
  
• Instead, the DNA strands just float about in the cytoplasm.
• They have a cell membrane but no mitochondria or ribosomes.
• There are no organelles (sub-cellular structures) whatsoever.
• Eukaryotic cells have a nucleus containing the DNA.
• The nucleolus creates the ribosomes. They synthesise the proteins the cells need.
• The endoplasmic reticulum is where the ribosomes attach. It is a passageway for the proteins synthesised by the ribosomes. It can be rough or smooth, depending on whether there are ribosomes attached to it.
• They also have mitochondria, for anaerobic respiration.