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Blood Cells - Microscope Image
All living things are made up of cells. They can be unicellular (formed by only one cell) or multicellular (formed by several cells).
Main characteristics of the animal cell
The cell is the smallest unit of the living being. In the human body there are different types of cells, and each type plays a specific role in maintaining life in the body.
Almost all cells have common characteristics regarding their shape, such as: plasma membrane, cytoplasm and nucleus. Remember that these characteristics are present in both animal and plant cells.
The plasma membrane is the cell's envelope, it is through it that the cell takes its shape and selects the substances that will enter or leave its interior (everything that enters or leaves the cell must cross this membrane).
The cytoplasm is composed of a fluid part where many chemical reactions take place that are necessary for the life of the cell. It encompasses everything in the cell from the plasma membrane to the nucleus, including the organelles (cell organs).
The organelles present in the cytoplasm of a eukaryotic (animal) cell are:
- Lysosomes: act in the digestion of organic substances.
- Smooth endoplasmic reticulum: has the functions of lipid synthesis, besides transporting and storing substances.
- Rough endoplasmic reticulum: Synthesizes proteins.
- Centrioles: act in the process of cell division in addition to causing flagella and cilia.
- Golgi Complex: Performs cellular secretion, besides forming the acrosome and lysosome.
- Ribosomes: make protein synthesis.
- Peroxisomes: they process oxidative reactions, acting in the process of cellular detoxification.
- Mitochondria: perform cellular respiration. They are present in almost all eukaryotes.
The nucleus controls the functions of cells, it has a double envelope and nuclear pores that control what goes from within it to the cytoplasm or vice versa. The vast majority of cells in the body have only one nucleus; however, there are cells that do not have it (this is the case with red blood cells) and there are still cells that have several (musculoskeletal cells).
Approximately 75 trillion cells form an adult human being.
- The area of biology that studies cells is known as cytology.
- Because they are extremely small, we can not observe the cells with the naked eye. This requires a powerful microscope, such as the electron microscope.
- The term eukaryote originates in the Greek language in which I means true and karyon means core.