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The Nucleus
The nucleus is the largest organelle of the cell, it is spherical in shape and is approximately 10μm in diameter. The nucleus is the control center of a cell directing its activities. A nuclear membrane surrounds the nucleus and separates it from the cytoplasm. The nucleus has a grainy appearance this is because the DNA molecules extend throughout the nuclear chromatin. The nucleus contains two important types of structures, chromosomes and nucleoli. Most of the cell’s DNA is found within the nucleus.
Nucleoli produce the RNA needed to make ribosomes. The nuclei membrane has pores, which can allow molecules such as messenger RNA to pass from the nucleus and into the cytoplasm where they can pass to the ribosomes so they can be interpreted.
Nucleic acid also within a nucleus contains all the information to make a copy of the cell as well as the information that controls the cell’s activities. The nucleus also contains centrioles, these are spindle like fibres that the chromosomes line up along during cell division.