The Cell and Nuclear Anatomy
The cell is the basic organizational unit of all living things. There are many different types of cells, but cells are unique to each type of organism. The one thing that all cells have in common is a membrane, which is like a semi-permeable plastic bag. The membrane is composed of phospholipids and has some transport holes, which are proteins that help certain molecules and ions move in and out of the cell. The cell is filled with a fluid called cytoplasm or cytosol.
Within the cell are a variety of organelles, groups of complex molecules that help a cell survive, each with its own unique membrane that has a different chemical makeup from the cell membrane. The larger the cell, the more organelles it will need to live.
Cell Structural Organization
All cells contain DNA and RNA and can synthesize proteins. Cells are the basic structural units of all organisms. Each cell consists of nucleic acids, cytoplasm, and a cell membrane. Specialized organelles, like mitochondria and chloroplasts, have specific functions within the cell. Different types of cells can have different functions. When many cells of the same type are grouped together, they are collectively called tissue. Tissues are grouped together in organs. Organs are grouped together in systems.
Nuclear Parts of a Cell
Nucleus (pl. nuclei): This is a small structure that contains the chromosomes and regulates the DNA of a cell. The nucleus is the defining structure of eukaryotic cells, and all eukaryotic cells have a nucleus, which contains genetic material. The nucleus contains a nuclear envelope, nucleoplasm, nucleolus, nuclear pores, chromatin, and ribosomes.
Chromosomes: These are highly condensed, threadlike rods of DNA. Short for deoxyribonucleic acid, DNA is the genetic material that stores information about the plant or animal.
Chromatin: This consists of the DNA and protein that make up chromosomes.
Nucleolus: This structure contained within the nucleus consists of protein, is small, round, does not have a membrane, is involved in protein synthesis, and synthesizes and stores RNA (ribonucleic acid).
Nuclear envelope: This encloses the structures of the nucleus. It consists of inner and outer membranes made of lipids.
Nuclear pores: These are involved in the exchange of material between the nucleus and the cytoplasm.
Nucleoplasm: This is the liquid within the nucleus, and is similar to cytoplasm.
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