ultra structure of eukaryotic cells

• The nucleus is surrounded by a double membrane called the envelope containing pores which enable molecules to enter and leave the nucleus. The nucleus also contains chromatin and a nucleolus which is the site of ribosome production

  
• Rough endoplasmic reticulum (RER) which is a series of flattened sacs enclosed by a membrane with ribosomes on the surface. RER folds and processes proteins made on the ribosomes

  
• Smooth endoplasmic reticulum (SER) is a system of membrane bound sacs. SER produces and processes lipids

  
• Golgi apparatus is a series of fluid filled, falttened and curved sacs with vesicles surrounding the edges. Golgi Apparatus processes and packages proteins and lipids. The golgi apparatus also produces lysosomes.

  
• Mitochondria are usually oval shaped, bound by a double membrane called the envelope. The inner membrane is folded to form projections called cristae with matrix on the inside containing all the enzymes needed for respiration.

  
• Centrioles are hollow cylinders containing a ring of microtubules arranged at right angles to eachother. Centrioles are involved in cell division.

  
• Ribosomes are composed of two sub units and are the site of protein synthesis.

  
• Lysosome is a vesicle containing digestive enzymes bound by a single membrane.

  
• The cytoskeleton of the cell plays an important role in providing mechanical strength as well as aiding transport within cells and enabling cell movement.