Chromosomes are located inside the nucleus as well. The substance of chromosomes is called
chromatin, which is made from deoxyribonucleic acid (DNA) strands and proteins. The DNA is arranged in a double helix.
CENTRIOLES Centrioles are structures made from nine bundles of three microtubules each. They are rodshaped and paired up to make the centrosome. Centrioles are crucial to cell division; they make the mitotic spindles that separate during act of cell division and pull the divided chromosomes to opposite sides of the cell. Centrioles are similar to basal bodies, which are at the base of each flagellum and cilium in those cells that have them.
RIBOSOMES Ribosomes are active in the process of making proteins. They act as the protein-making factories inside the cell. Each ribosome is made from a large and small subunit. Collectively, the
ribosomes are found on rough endoplasmic reticulum or together form polyribosomes within the cytoplasm. Some ribosomes are found free-floating in the cytoplasm unattached to anything. They make use of ribonucleic acid (RNA), which is sent from the nucleus to allow for protein synthesis in the ribosomes themselves.
MITOCHONDRIA Mitochondria are important organelles in that they generate the ATP, which is the universal form of energy used by all cells in the body. The fuel used to make ATP is primarily glucose, which goes through a series of reactions called glycolysis and the Krebs cycle in order to make ATP from ADP and phosphate. Mitochondria are roughly oval in shape and are membranebound with cristae that form small shelves or infoldings within the structure. It is within the mitochondrion that the Krebs cycle takes place. Cells that are highly metabolically active contain a lot of mitochondria. There is a small amount of genetic material within the mitochondria as well. 12
