人类初级细胞可以告诉人体时间:献给史蒂文·A. 棕色 棕色 棕色 棕色

The cell cycle refers to the sequence of events occurring throughout a typical cell’s life. In eukaryotic cells, the somatic cell cycle has two stages: interphase and the mitotic phase. During interphase, the cell grows, performs its basic metabolic functions, copies its DNA, and prepares for mitotic cell division. Then, during mitosis and cytokinesis, the cell divides its nuclear and cytoplasmic materials, respectively. This generates two daughter cells that are identical to the original...

The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.

The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...

The cell cycle refers to the sequence of events occurring throughout a typical cell’s life. In eukaryotic cells, the somatic cell cycle has two stages: the interphase and the mitotic phase. During interphase, the cell grows, performs its basic metabolic functions, copies its DNA, and prepares for mitotic cell division. Then, during mitosis and cytokinesis, the cell divides its nuclear and cytoplasmic materials, respectively. This generates two daughter cells that are identical to the original...

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term "cell" based on the resemblance of the small subdivisions in the cork to the rooms that monks inhabited, called cells. About ten years later, Antonie van Leeuwenhoek became the first person to observe the living and moving cells under a microscope. In the century that followed, the theory that cells represented the basic unit of life developed.
Multicellular organisms...

The first thing a clinician sees is the skin, so the examination of the skin should be part of any thorough physical examination. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal if untreated. A couple of the more noticeable disorders, albinism and vitiligo, affect the appearance of the skin and its accessory organs.
Albinism
Albinism is a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily...