Cell Biology Review Materials, Medical Cell Biology Short Answer Questions

First chromatin is compressed sevenfold to become nucleosomes, then sixfold to become solenoids, then fortyfold to become supersolenoids, and five times to become chromatids.

1 Active transport Passive transport Osmotic water absorption Cytocytosis 2 Apoptosis refers to the autonomous and orderly death of cells controlled by genes in order to maintain the stability of the internal environment. Apoptosis is different from cell necrosis, apoptosis is not a passive process, but an active process, which involves the activation, expression and regulation of a series of genes.

3 The nucleus, nuclear membrane, and nucleolus disappear and chromosomes are synonymous.

4 I don't know this.

5 1.secretion of chemical signals for communication: endocrine, paracrine, autocrine, chemical synapse;

2.Contact-dependent communication: direct contact between cells, signaling molecules and receptors are the communication methods of transmembrane proteins of cells; 3.Gap ligation enables metabolic or electrical coupling.

1.For small molecule substances, there are active transport and passive transport. Passive transport is further divided into free diffusion and assisted diffusion, also known as dissimilated diffusion.

Among them, active transport requires a carrier and ATP to carry out, and the reverse concentration gradient is used: alien diffusion requires only a carrier but does not require ATP, free diffusion does not consume ATP or a carrier, and passive transport is a pro-concentration gradient.

For biological macromolecular substances, like proteins, glucose and the like transmembrane transport are endocytosis and exocytosis.

2.To put it simply, apoptosis refers to the programmed death of cells, in which cells are degraded by their own enzymes and "commit suicide" according to certain steps, and their dead cells are still a whole and are eventually engulfed by white blood cells. Cell necrosis, on the other hand, will cause the cell wall to rupture, and the contents will leak out, which will affect the surrounding cells.

And cell death is caused by external conditions. To put it bluntly, apoptosis is usually normal, while necrosis is abnormal.

3.The early stage I is divided into five sub-stages: the thin line stage, the line conjunction, the thick line stage, the double line stage and the terminal period.

Thin line phase: Chromosomes are thin lines that agglutinate on one side of the nucleus.

Merging phase: Homologous chromosomes begin to pair, SCs begin to form, and the remaining DNA is synthesized. Two chromosomes that are joined together under the light microscope are called bivalents.

Each pair of homologous chromosomes is duplicated and contains four chromatids, so it is also called a tetrad

Thick line phase: The period when chromosomes become shorter and bond closer, and this period occurs when the non-sister chromatids of homologous chromosomes are exchanged.

Doublet phase: Paired homologous chromosomes repel each other, begin to separate, cross-terminalize, and some loci are still connected. The oocytes of some animals stay during this period, forming the lampbrush chromosomes.

Terminal phase: almost complete end-to-end crossing, rupture of the nuclear envelope, and disintegration of the nucleolus. It is the best period for chromosome counting.

Autotrophic type: Like green plants, the nutritional method of using organic matter produced by itself to maintain life is called autotrophics, which is an important characteristic shared by all kinds of green plants. Such as photosynthesis in plants, chemical synthesis of nitrifying bacteria.

2. Heterotrophic type: the nutritional mode that cannot directly synthesize inorganic matter into organic matter, and must ingest ready-made organic matter to maintain life, is called heterotrophic type. Heterotrophic includes three modes: symbiotic, parasitic, and saprophytic.

5.through signaling molecules;

Adhesion or ligation of surface molecules between adjacent cells;

Through the adhesion of cells to the extracellular matrix.

Of the three ways, the first does not require direct contact with the cell and relies entirely on the contact between the ligand and the receptor to transmit the information, while the latter two require contact through the cell.