Used blood leaves the breasts through the veins and is pumped back to the heart and lungs to be refreshed. Lymph must also be refreshed and recycled. Lymph drains away from your breasts through the lymphatic system, which is made up of lymphatic channels and lymph nodes.
exists and is an alternate of . Chromosomes are located in the nucleus of a cell in eukaryotes. In prokaryotes (which lack a cell nucleus) chromosomes are circular in shape usually found attached to the plasmid membrane. Smaller circular DNA known as plasmids are also found in the prokaryotic cells and are thought of as smaller versions of chromosomes.
What is a chromosome? In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure. Chromosomes are not visible in the cellâs nucleusânot even under a microscopeâwhen the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. Most of what researchers know about chromosomes was learned by observing chromosomes during cell division.