Ribosomes are present on all cells, but are very small and unlikely to be seen with a standard light microscope; at best, they may look like tiny grains, but their structure will not be discernible. Ribosomes are found both free in the cytoplasm and embedded on the surface of the rough endoplasmic reticulum. They are involved in protein synthesis.
Vesicles are generally small, and often are clear, so are not likely to be visible under the light microscope. They are involved in the transport of materials, both within the cell and across the cell membrane.
Cytoplasm is present in all cells, but you can't really see it, you actually look through it to see the other parts of the cell. It is a clear watery fluid, and provides support and transport within the cell.
The cytoskeleton is a network of fibers and tubes that provides internal support and shape to the cell.These are very fine and usually are not visible unless the cell is in the midst of mitosis.
Peroxisomes and lysosomes are very tiny membrane sacs filled with enzymes that help the cell break down materials. Peroxisomes break down toxins and lysosomes break down things the cell has ingested. Both are quite tiny and probably not visible with a standard light microscope.
Usually, only the cell's nucleus is visible through a light microscope. In plant cells, the cell wall and vacuole may also be visible. However, there are many cell parts (also called organelles) that are too small to be seen through a light microscope. Three examples of these organelles are...
ribosomes - synthesize protein for the cell
endoplasmic reticulum - transport protein throughout the cell
mitochondria - produce energy for the cell
These cell parts can be viewed using a more powerful type of microscope called an electron microscope .