space enclosed by secondary walls

The primary wall and intercellular layer at the bottom of the pit cavity

Located in the outermost layer of the cell nucleus, it is composed of two parallel but discontinuous membranes, the inner and outer layers.

A filament-like structure composed of DNA, histones, non-histone proteins, and a small amount of RNA

Very obvious nodules in the nucleus, spherical in shape, without membrane coating, one or more

Protein-based grid structure system

chloroplast

chromatic body

white body

Observed under an electron microscope, mitochondria are wrapped by double membranes, namely the outer membrane and the inner membrane. The membrane is filled with matrix. There are many tubular or pleated structures formed by the inner membrane folding inward in the matrix, called (crista) (Fig. 1-15, Figure 1-16). The formation of greatly expands the surface area of ​​the inner membrane. Mitochondria are the place where cells carry out respiration, providing direct energy for cell life activities. Therefore, mitochondria are known as the "power factories" in cells.

It is an interconnected network structure composed of tubular or sac-like cavities surrounded by membranes. There are two types of endoplasmic reticulum: smooth endoplasmic reticulum and rough endoplasmic reticulum. Rough endoplasmic reticulum is mostly flat and neatly arranged. It is named after a large number of ribosomes distributed on the outer surface of the membrane. The endoplasmic reticulum and ribosomes form a complex functional structure, whose main function is to synthesize and transport proteins. The surface of the smooth endoplasmic reticulum has no ribosome binding and is mostly branched and tubular. It is the site of lipid synthesis.

It consists of flat vesicles stacked together and a large number of vesicles surrounding them (Figure 1-17). Cells with strong secretory activity, rich in Golgi apparatus

They are vesicles wrapped by a single membrane and contain a variety of acidic hydrolases, such as proteases, lipases, nucleases, etc. Therefore, their main function is to degrade biological macromolecules and decompose damaged or dysfunctional cellular structures in cells. fragments, allowing the materials that make up these structures to be reused by cells. Plant cells differentiate into vessels, sieve tubes, and fiber cells In the process, lysosomes are involved

It is a granular organelle coated by a single membrane with a diameter of about 0.5~1pm. Microbodies can be divided into two types: peroxisomes and glyoxylate cycle bodies. Peroxisomes are distributed in plant leaf cells and participate in the photorespiration process together with chloroplasts and mitochondria; the glyoxylate cycle exists in germinating seeds containing a large amount of fat. It plays an important role in converting fat into sugar.

Coated by a single membrane, the membrane is filled with fluid called cytosol. The vacuoles in young plant cells are small and numerous. As the cells grow, the vacuoles gradually grow larger and merge with each other, often forming a large central vacuole. Mature plant cells have a large central vacuole, which is another feature that distinguishes plant cells from animal cells. After the large central vacuole is formed, the rest of the cytoplasm, together with the nucleus, is squeezed into a thin layer close to the cell wall.

It is a granular structure, not wrapped by a membrane, with a diameter of 25nm. The main components are protein and RNA. Ribosomes exist in two states within cells: one type of ribosome is attached to the surface of the endoplasmic reticulum and forms a rough endoplasmic reticulum with it; the other type of ribosome is dispersed in the cytoplasmic matrix and is in a free state

microtubules

microfilament

intermediate fiber