What Are the Different Parts of Human Cell Structure?
Like other systems, cells also have borders, there are several components of division of labor and cooperation, and information centers regulate cell metabolism and inheritance. The structure of the cell is complex and delicate, and various structural components coordinate and coordinate, so that life activities can self-regulate in a changing environment and proceed in a highly orderly manner.
- In fact, viruses are a large area, and it also includes a branch-subviruses (such as prions are a type of subviruses). Subviruses are organisms with simpler structures than viruses. But from a macro perspective, subviruses are also classified in the field of virology. Therefore, except for viruses, other organisms are composed of cells, including eukaryotic and prokaryotic.
- Looking at the cells of a plant under an optical microscope, you can see that its structure is divided into the following four parts:
- Cell wall: Located in the outermost layer of plant cells, it is a thin transparent wall. It is mainly composed of cellulose and pectin, with large pores and free passage of material molecules. The cell wall supports and protects the cells.
- Cell membrane: The inner side of the cell wall is closely adhered to a very thin film called a cell membrane. This film is composed of protein molecules and lipid molecules. Small molecules such as water and oxygen can pass freely, while certain ions and macromolecules cannot pass freely. Therefore, in addition to protecting the interior of cells, It also has the function of controlling the ingress and egress of cells: neither allow useful substances to leak out of the cells arbitrarily, nor allow harmful substances to easily enter the cells.
- Cell membranes are not easily distinguishable under a light microscope. Observation with an electron microscope shows that the cell membrane is mainly composed of protein molecules and lipid molecules. In the middle of the cell membrane is a bilayer of phospholipids, which is the basic skeleton of the cell membrane. On the outside and inside of the phospholipid bilayer, there are many spherical protein molecules, which are embedded in the phospholipid molecular layer at different depths (Figure 3-1-2) or cover the surface of the phospholipid molecular layer. Most of these phospholipid molecules and protein molecules can flow, it can be said that the cell membrane has a certain fluidity. This structural feature of the cell membrane is very important for it to perform various physiological functions.
- Cytoplasm: A thick, transparent substance surrounded by a cell membrane, called a cytoplasmic matrix. Refractive particles can also be seen in the cytoplasm. Most of these particles have a certain structure and function, similar to various organs of the organism, so they are called organelles. For example, in the mesophyll cells of green plants, many green particles can be seen. This is an organelle called a chloroplast . Photosynthesis of green plants occurs in the chloroplast. In the cytoplasm, one or several vacuoles can often be seen , which are filled with liquid, called cytosol . In mature plant cells, the vacuoles merge into a central vacuole, which takes up most of the entire cell's volume.
- The cytoplasm is not frozen and stationary, but slowly moving. In cells with only one central vacuole, the cytoplasm often circulates around the vacuole, which promotes the transport of intracellular materials and strengthens the interconnections between organelles. Cytoplasmic motion is a life phenomenon that consumes energy. The more vigorous a cell's life activity is, the faster the cytoplasm flows, and conversely, the slower it is. After a cell dies, its cytoplasmic flow stops.
- In addition to chloroplasts, there are some organelles in plant cells, which have different structures and perform different functions, and jointly complete the life activities of cells. The structure of these organelles needs to be observed with an electron microscope. The cell structure observed under the electron microscope is called submicrostructure.
- Mitochondria: It is linear and granular, hence the name. In mitochondria, there are many kinds of particles related to respiration, that is, a variety of respiratory enzymes. It is the place where cells perform respiration. Through respiration, organic matter is oxidized and decomposed, and energy is released.
- Comparison of animal and plant cells 
- Endoplasmic reticulum: The endoplasmic reticulum is a reticular duct system consisting of membranes in the cytoplasm. It is connected to the cell membrane and plays an important role in the synthesis and transportation of intracellular proteins and other substances.
- Ribosomes: Ribosomes are granular bodies that mostly exist on the outer surface of the endoplasmic reticulum membrane and are an important base for protein synthesis.
- Centrosome: Centrosome exists in animal cells and some lower plant cells. Because it is located close to the nucleus, it is called centrosome. Centrosome is closely related to mitosis of cells.
- Nucleus: The cytoplasm contains an approximately spherical nucleus, which is composed of a more viscous substance. The nucleus is usually located in the center of the cell. The nucleus of a mature plant cell is often pushed to the edge of the cell by a central vacuole. There is a substance in the nucleus, which is easily stained with magenta and hematoxylin and other basic dyes, called chromatin. The genetic material used by organisms for seeding and succession is chromatin. When cells undergo mitosis, chromatin changes into chromosomes.
- DNA is a macromolecule of organic matter, also called DNA, which is the genetic material of organisms. During mitosis, the chromosome replicates, and the DNA is copied into two copies, which are evenly distributed to the two daughter cells, so that the number of chromosomes in the offspring is constant, thereby ensuring the stability of the genetic characteristics of the offspring.
- In short, both plants and animals are made of cells. Cells are the basic unit of the structure and function of an organism.