Prokaryotic cells: cells that do not have a clear nucleus surrounded by a membrane, are small in size, have a simple structure, and are of primitive evolutionary status.

Eukaryotic cells: cells that contain a true nucleus (a nucleus surrounded by a nuclear membrane), have more than one chromosome, and are capable of undergoing mitosis.

Protoplasm: Protoplasm is the general term for the living matter within cells. Its main components are carbohydrates, proteins, nucleic acids, and lipids. Protoplasm differentiates to produce the cell membrane, cytoplasm, and nucleus, forming the protoplast, or cell, with its specific structural system. An animal cell is a protoplast. Plant cells are composed of a protoplast and a cell wall.

Plasmid: A genetic factor that can replicate autonomously outside the nucleus. It is a naked circular DNA molecule that can be lost from the cell without affecting the normal life of the cell. It is often used as a carrier of gene recombination and gene transfer in genetic engineering.

Viroids: A class of pathogenic agents smaller than any known virus that parasitize higher organisms (primarily plants). They lack a protein coat and consist only of free-living RNA molecules, though DNA forms also exist.

Cell culture: The process of removing tissues from the body and dispersing them (mechanically or by enzymatic digestion) into single cells, allowing them to survive, grow, reproduce, and be passed down through generations under artificial culture conditions, and observing their growth, reproduction, contact inhibition, aging and other life phenomena.

Cell fusion: The phenomenon of two or more cells fusing into a binucleate or multinucleate cell, usually mediated by inactivated viruses or chemicals, but also by electrical stimulation.

Monoclonal antibody: An antibody that targets only a certain antigenic determinant cluster and is obtained by cloning a single antibody-secreting B lymphocyte. It has the characteristics of strong specificity and can be produced on a large scale.

Cell Biology: Cell biology is the science that studies the basic laws of cell life activities. At three different levels: microscopic, submicroscopic, and molecular, it focuses on studying cell structure and function, cell proliferation, differentiation, aging, apoptosis, eukaryotic gene expression and regulation, and cell origin and evolution.

Liposome: An artificial membrane prepared based on the fact that phospholipid molecules can form a stable lipid bilayer membrane in the aqueous phase.

Cell coat: Animal cells have a carbohydrate-rich layer on their surface, called the cell coat. The cell coat is composed of oligosaccharide chains extending from the glycoproteins and glycolipids that make up the plasma membrane and is essentially part of the plasma membrane structure.

Gap junctions: Gap junctions are intercellular connections in animal cells via connexons. The term "gap" has two meanings: first, at gap junctions, there is a 2-3 nm gap between adjacent cell membranes; second, at the junction of gap junctions, the lipid bilayers are not directly connected, but rather two connexons dock to form a channel, allowing small molecules to flow directly from one cell to another through this gap channel.

Extracellular matrix: The extracellular matrix is ​​the most abundant in connective tissue, mainly secreted by fibroblasts, and occupies most of the extracellular space of connective tissue. It is a fine and intricate network structure composed of proteins and polysaccharides secreted by cells. It not only participates in the maintenance of tissue structure, but also has a full range of effects on basic life activities such as cell survival, morphology, function, metabolism, proliferation, differentiation, and migration. Extracellular matrix components can send signals to cells through specific receptors on their cell surfaces, and transmit signals to the cytoplasm and even the nucleus through the cytoskeleton or various signal transduction pathways, affecting gene expression and cell activity.

Cell communication: Information sent by one cell is transmitted through a medium to another cell, generating a corresponding response. Coordinating cell functions and controlling cell growth, division, differentiation, and apoptosis are essential for the development of multicellular organisms and the construction of tissues.

Cell recognition: The process by which cells selectively interact with extracellular signaling molecules (ligands) through surface receptors, leading to a series of physiological and biochemical changes within the cell, which ultimately manifest as biological effects on the cell as a whole.

Signaling pathway: Cells receive external signals and convert them into intracellular signals through a set of specific mechanisms, ultimately regulating the expression of specific genes and causing cellular responses. This series of reactions is called a cell signaling pathway.

Active transport: The method by which substances are transported across the membrane from low concentration to high concentration against the concentration gradient or electrochemical gradient. It requires energy from the cell and the participation of carrier proteins.

Passive transport: Substances are transported from high concentration to low concentration along the concentration gradient through free diffusion or facilitated diffusion. The power of transport comes from the concentration gradient of the transported substance and does not require energy from the cell.

Endocytosis: The plasma membrane is invaginated to form vesicles, which encapsulate substances outside the cell or on the surface of the plasma membrane and transport them into the cell (pinocytosis and phagocytosis).

Co-transfer: The process by which peptide chains are transferred to the endoplasmic reticulum while being synthesized is called co-transfer.

Post-translocation: The process of proteins being synthesized in the cytoplasmic matrix and then transferred to these organelles is called post-translocation.

Microsomes: spherical membrane vesicles formed by the self-fusion of fragmented endoplasmic reticulum during cell homogenization and differential centrifugation.

Signal spot: The signal spot is a three-dimensional surface structure formed by several signal peptides. These signal peptides gather together to form a spot that is recognized by phosphotransferase.

Signal peptide: It is the determining factor for protein entry into the endoplasmic reticulum. It is located at the N-terminus of the protein and is generally 16 to 26 amino acid residues long. It is usually removed after entering the endoplasmic reticulum.

Oxidative phosphorylation: The process by which electrons are transferred from NADH or FADH2 to oxygen to form water, accompanied by the phosphorylation of ADP to form ATP.

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