animal cells under a light microscope

• the nucleus is the largest organelle inside the cell and measures about 10um in diameter. It is surrounded by the nuclear envelope which has pores. these pores allow materials to pass in and out. Inside is loosely coiled DNA called which is attached to proteins called histones. DNA contains the instructions for making proteins. When a cell divides, the chromatin condenses pulling the DNA into thread-like structures called chromosomes. The latter are only visible when a cell divides. a spherical structure called a nucleolus helps to make the ribosomes of the cell.
• outside the nucleus, a small circular structure called a centriole can sometimes be seen. this structure helps to form the spindle fibres when a cell divides.
• the cytoplasm quite often appears as a granular structure under the light microscope. it contains many different organelles some of which can be seen using a light microscope and special stains.
• sometimes rod shaped structures called mitochondria can be found. this is the site of aerobic respiration.
• another organelle, which modifies or changes proteins made in the cell can also be seen. this is called the Golgi body. such modified proteins are then released from the cell in vesicles.
• the outer part of the cell, which is partially permeable, is the plasma membrane. it controls what enters and leaves the cell