Composition of plant cell protoplasts

Cell membrane, cytoplasm and nucleus.

Plant cell is the basic unit of structure and function of plant life activities, which is composed of two parts: protoplast and cell wall.

Protoplasts are a general term for all substances in the cell wall, mainly composed of cytoplasm and nucleus, and there are several different organelles in the cytoplasm or nucleus, in addition to cell fluid and post-inclusions. Organelles are endoplasmic reticulum, plastid, mitochondria, Golgi apparatus, and ribosomes, among others.

The cell wall is a unique structure of plant cells, which has the function of protecting protoplasts and maintaining a certain shape of cells. The cell wall can be divided into the intercellular layer, the primary wall, and the secondary wall. The intercellular layer is shared by adjacent cells; The primary wall is located on the inner side of the intercellular layer and is produced during cell growth; The secondary wall is formed after the cell stops enlarging and is attached to the inner part of the primary wall, and some cells do not have a secondary wall.

The plant cell is the basic unit of structure and function of living organisms, the basic unit of life activities, and the basis of ontogeny and phylogeny of organisms.

Answer]:The preparation methods of plant protoplasts mainly include mechanical separation method and enzymatic hydrolysis separation method. In the mechanical separation method, the cells are slightly separated from the plasma wall in the hypertonic sugar solution, and after the protoplasm shrinks into a ball, the tissue is mechanically ground and the protoplast is released from the damaged cell wall.

Enzymatic hydrolysis and separation method is to digest the components of the cell wall by cellulase, hemicellulase, pectinase, etc. to obtain protoplasts.

Categories: Education Science >> Entrance Examination >> College Entrance Examination.

Analysis: Plastids are organelles unique to green plant cells and are easily visible under a light microscope. In juvenile cells, plastids that have not yet differentiated and matured are called preplastids.

As the cell grows, the preplasts can differentiate into mature plastids. Depending on their color and function, mature plastids are divided into three categories: chloroplasts, chromosomes, and white bodies.

1 Chloroplast Chloroplast is a chlorophyll-containing plastid, which is mainly found in the parenchyma tissue cells of the green part of the plant body, and is the site of photosynthesis of green plants, so it is an important plastid.

2 Chromosomes Chromogens are plastids that contain pigments. Chloroplasts are also chromoplasts, but it is customary to refer to chromoplasts other than chloroplasts as chromoligands or variegotles.

The colored body contains lutein and carotene and is red or orange-yellow in color. It is found in petals and fruits, and can be seen in tomato and pepper (red) pulp cells. The main function of chromosomes is to accumulate starches and lipids.

3 White body The white body does not contain visible pigments, which is also called chaotic Zheng refers to the colorless body. On the white body in the cells of the storage tissue, starch or protein often accumulates, forming starch and aleurone grains that are many times larger than its original volume, which become the storage material in the cell. When the white body accumulates starch, it first starts from one place to form a core called the umbilicus, and then continues to accumulate around the nucleus, forming a concentric ring pattern around the umbilicus.

Due to the strength of the sunshine and the temperature in a day, the starch grains often appear eccentric. If you look at potato starch grains, you can see:

Some cells have white bodies that contain colorless prochlorophyll, which can be converted into chlorophyll when exposed to light, and white bodies turn green, so some people think that white bodies can also become chloroplasts.

Plant cells are composed of four parts: cell wall, cell membrane, cytoplasm, and nucleus.

The cytoplasm of plant cells includes cytoplasmic matrix and organelles.

The organelles of plant cells include: endoplasmic reticulum, mitochondria, Golgi apparatus, ribosomes, lysosomes, chloroplasts, vacuoles.

1. Cell wall: supports the structure and morphology of cells and protects cells.

2. Cell membrane: It has a similar function to the cell membrane of animals, which is a semi-permeable membrane and has the function of exchanging substances and nutrients.

3. Cytoplasm: It provides substances and places for cell metabolism.

4. Nucleus: the place where genetic material is stored and replicated, and the control center of life activities.

Generally, it includes: cell wall, cell membrane, cytoplasm, and nucleus.

Among them, cytoplasm includes: cytoplasmic matrix and organelles.

Organelles include: endoplasmic reticulum, mitochondria, Golgi apparatus, ribosomes, lysosomes, chloroplasts, and vacuoles.

The structure of plant cells: the cell wall: it plays a supporting and protective role in the cell membrane and its internal structure; Cell membrane:

control the entry and exit of substances and other functions; Cytoplasm: a liquid and fluid substance that exists outside the nucleus within the cell membrane; The function of the nucleus is mainly to store and transmit genetic information.

1.Cell wall

The cell wall is one of the distinctive features of plant cells, surrounded by the outermost part of plant cells, its main function is to support and protect the cell membrane and its internal structure, and the component of the cell wall is cellulose, which is relatively "hard".

2.Cell membrane:

The cell membrane is an extremely thin membrane that clings to the cell wall and is difficult to observe with a light microscope under normal conditions. The chemical components of the cell membrane are proteins and lipids, and the cell membrane has the following functions:

control the entry and exit of substances; Receiving and transmitting external signals; Resist the invasion of germs, etc.

3.Cytoplasm

Cytoplasm is a liquid and flowing substance that exists outside the nucleus within the cell membrane. There are various structures within the cytoplasm;

Vacuoles: In young plant cells, vacuoles are small and scattered, in mature plant cells, there is only one large vacuole, which can account for less than 90% of the cell volume, the vacuole is filled with cell fluid, the main component of cell fluid is water, in addition to dissolving a variety of substances, such as sugar, organic acids, proteins, etc., some vacuoles also contain pigments, so that the cells show different colors. The functions of vacuoles are mainly osmoregulation, storage and digestion.

Chloroplast: A small green particle in the cytoplasm that is the site of photosynthesis in plants. Chloroplasts contain chlorophyll, so most of the cells containing chloroplasts are green, and some fruits can be transformed into chromosomes during the ripening process, making the fruit appear in various colors.

Mitochondria: are the sites of cellular respiration and are small and difficult to observe under an ordinary light microscope.

4.Nucleus

The nucleus is an important part of the cell, in young plant cells, the nucleus is larger, spherical, located in the cell, with the growth of the cell and the formation of vacuoles, the nucleus moves to the part close to the cell wall, which is hemispherical or round. The function of the nucleus is mainly to store and transmit genetic information.