The Plant Cell


There are several important organelles in a plant cell.  
 

    


The nucleus is often the largest organelle in a plant cell.  
It is enclosed by a double membrane called the "nuclear envelope".  
 The nucleus serves to protect DNA information and is perforated with holes called nuclear pores. 
Inside the nucleus is a special structure called the nucleolus.   The nucleolus is responsible for assembling ribosomes.

      Ribosomes are composed of proteins and ribosomal RNA. 
They are found in four areas of the plant cell: the cytoplasm, the surface of the endoplasmic reticulum, the mitochondria, and on chloroplasts.

There are two main types of ribosomes: free ribosomes and attached ribosomes.

Attached ribosomes are attached to the endoplasmic reticulum and serve as sites for protein synthesis.  Proteins synthesized on these ribosomes will be exported from the cell, moved into other organelles of the endomembrane system, or incorporated into membranes.

Protein synthesis also occurs on free ribosomes

Plant cells are unique because of their chloroplasts and their cell walls.

Chloroplasts process energy for the plant cell.  The endosymbiotic theory explains the origin of chloroplasts in the plant cell. 

Vacuoles found in eukaryotes are organelles filled with aqueous solutions containing various dissolved substances. 
Vacuoles are used for the storage of waste and food.  They are also useful for maintaining cell structure and water balance.

        The cytoskeleton is a series of intracellular proteins that aid in
                  the support, shape, and movement of the cell.  

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