Structure and function of cells. What is the relationship between cell structure and function

"Structure determines function" is one of the basic principles of biology, if a cell has a certain structure, it should have the corresponding physiological function of that structure.

If a cell is found to have a certain function, it can also reflect what structure the cell should have and the characteristics of that structure.

For example, plasma cells can secrete antibodies in large quantities, so it can be assumed that the organelles related to secreted proteins in plasma cells, such as ribosomes, endoplasmic reticulum, and Golgi apparatus, are more developed than other normal cells, but it cannot be assumed that cells do not have relevant functions if they do not have a certain structure.

Because prokaryotic cells have a simple structure, do not have a well-developed biofilm system, and do not have a variety of organelles, but prokaryotic cells contain chemicals related to specific functions, so they appear to have related functions even if they do not have a specific structure.

For example, E. coli does not contain endoplasmic reticulum and Golgi apparatus, but it can still process proteins because its cytoplasmic matrix contains enzymes needed to process proteins.

The structure of a cell is a cell wall, a cell membrane, a cytoplasm, and a nucleus. Function: The cell wall plays a supporting and protective role for the cell. The nucleus is the site where genetic material is stored and replicated, and is the control center for cellular heritability and cellular metabolic activity.

1.The structure and function of cell membranes and the three ways in which substances enter and leave the cell are the focus of the teaching. Learning the structure and function of cell membranes has a great impact on the learning of subsequent chapters.

Knowledge of cell membranes is fundamental to learning about water metabolism, mineral metabolism, photosynthesis and respiration, and animal metabolism in plants. The structural characteristics and functional properties of cell membranes are closely related to the material exchange, energy conversion, information transmission, and hormone regulation of cells.

2.Among the seven organelles mentioned in the textbook, mitochondria and chloroplasts should be the focus. These two organelles are closely related to cellular energy conversion. Knowledge of mitochondrial and chloroplast structure and function is fundamental to learning about respiration and photosynthesis.

Microstructure: The structure of a cell that can be observed in a normal light microscope.

Submicroscopic structure: Various microstructures in cells that cannot be clearly resolved can be observed under an ordinary light microscope.

Prokaryotic cells: Cells are small and do not have a formed nucleus. The material that makes up the nucleus is concentrated in the nuclear region, there are no chromosomes, DNA does not bind to proteins, there is no nuclear membrane, no nucleolus; Organelles have only ribosomes; There is a cell wall with a different composition than eukaryotic cells.

Eukaryotic cells: Cells are larger, have a true nucleus, have a certain number of chromosomes, have a nuclear membrane, have nucleolus, and generally have a variety of organelles.

1.The cell wall is a membranous structure wrapped around the cell membrane, with a thickness of 10 80 nanometers (nm), and its composition is complex, which varies from different bacteria, and the main components are peptidoglycan, whose main function is to maintain the intrinsic morphology of the cell and maintain the osmotic pressure inside and outside the cell.

2.Compared with eukaryotic cell membranes, the cell membrane contains cholesterol but has the functions of transport, biosynthesis, secretion and respiration of intracellular and extracellular substances.

3.The cytoplasm is located in the protoplasm inside the cell and contains a variety of important structures such as nucleoproteosomes and plasmids.

4.The nucleoplasm is formed by the aggregation of DNA and RNA, the genetic material of the bacteria in the cytoplasm, and does not have a complete nuclear structure, so it is also called nucleoide.

The above is what is the relationship between cell structure and function that I have sorted out for you.

The structure and function of the cell are as follows:

The structure of a cell mainly consists of three parts: the cell membrane, the cytoplasm, and the nucleus.

When cells are observed under an electron microscope, they can be distinguished into membrane-phase structures and non-membrane-phase structures. The cell membrane is a thin film on the surface of the cell, its thickness is about nanometers, and the chemical composition of the cell membrane is mainly lipids, proteins, and a certain amount of sugars. Under the electron microscope, the cell membrane can be seen that its structure is divided into three layers, the inner and outer layers are dark and dark, and the middle layer is light.

Also, cytoplasm is the part between the cell membrane and the nucleus, including the organelles and the matrix.

Function] 1. The boundary of the cell membrane-system.

A cell is an independent system, and the cell membrane is the boundary of this system, which is mainly composed of phospholipid bilayers and proteins, as well as a small amount of sugars.

1.Separates cells from the outside environment.

This function clearly divides the cell into extracellular and intracellular, ensuring the relative stability of the internal environment of the cell.

2.Controls the movement of substances in and out of cells.

It is impossible for cells to absorb external substances indiscriminately, so it has such a function, which enables cells to selectively absorb and eliminate substances, and at the same time, it also relatively protects cells from being invaded by harmful substances and causing diseases.

3.Communicate information between cells.

With this function, cells can cooperate with each other to support the life activities of animals and plants.

Second, the division of labor and cooperation within the organelle-system.

With a stable internal environment, production needs to begin, and just as a factory cannot be responsible for all its operating processes, there is also a division of labor within the cell, and different organelles have different functions.

Cells are made up of a nucleus and cytoplasm and have a membrane on their surface. Cells are the basic structural and functional units of living organisms. Cells are so small that they can only be seen under a microscope and come in a variety of shapes.

1.Cell membranes

The inside of the cell wall is clinging to a very thin membrane called the cell membrane. This thin film is made up of protein molecules and phospholipid bilayers, through which small molecules such as water and oxygen can pass freely, while certain ions and macromolecules cannot pass freely. Therefore, in addition to protecting the inside of the cell, it also has the role of controlling the movement of substances in and out of the cell

Neither allow useful substances to leak out of the cell at will, nor allow harmful substances to easily enter the cell. In addition, it enables the exchange of information between cells.

2.Cytoplasm

The thick, transparent substance encased in the cell membrane is called cytoplasm. In the cytoplasm, some refractive particles can also be seen, most of these particles have a certain structure and function, similar to various organs of organisms, so they are called organelles. For example, in the mesophyll cells of green plants, many green particles can be seen, which is an organelle called chloroplast.

Photosynthesis of green plants takes place in chloroplasts. In the cytoplasm, one or several vacuoles are often also seen, which are filled with fluid, called cell sap. In mature plant cells, vacuoles merge into one large vacuole, which accounts for most of the volume of the entire cell.

The cytoplasm is squeezed into one layer. The cell membrane as well as the cytoplasm between the vacuolar membrane and the two membranes is called the protoplasmic layer.

3.Nucleus

The cytoplasm contains a nearly spherical nucleus and is made up of a more viscous substance. The nucleus is usually located at the core of the cell, and the nucleus of mature plant cells is often pushed to the edge of the cell by vacuoles.

The function of the nucleus is to preserve genetic material, control biochemical synthesis and cell metabolism, determine the performance of cell or body traits, and pass genetic material from cell (or individual) generation to generation. However, the nucleus does not function in isolation, but interacts with the cytoplasm and interdepends to show the life process of cell unity. The nucleus controls the cytoplasm; Cytoplasm also plays an important role in cell differentiation, development, and genetics.