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The connexon complexes stretches across the cell membrane and when two adjacent cell connexons interact, they form a complete gap junction channel. [9] [10] Connexon pores vary in size, polarity and therefore can be specific depending on the connexin proteins that constitute each individual connexon.
In eukaryotic cells (cells that package their DNA within a nucleus), chromosomes consist of very long linear double-stranded DNA molecules. During the S-phase of each cell cycle ( Figure 1 ), all of the DNA in a cell is duplicated in order to provide one copy to each of the daughter cells after the next cell division.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. It is not found in all cell types. Some cells, such as the conducting cells in xylem , possess a secondary wall containing lignin , which strengthens and waterproofs the wall.
During cytokinesis in animal cells, a contractile ring made up of actin filaments forms, and this ring pinches to divide the cell into two daughter cells. [6] The cells are able to separate due to the formation of a cleavage furrow, which pinches in a centripetal fashion (from the outside of the cell towards the center of the cell). [6]
After the successful completion of the G 2 checkpoint, the final checkpoint in interphase, the cell proceeds to prophase, or in plants to preprophase, which is the first stage of mitosis. G 0 phase is viewed as either an extended G 1 phase where the cell is neither dividing nor preparing to divide, or as a distinct quiescent stage which occurs ...
Germ cells, or gametes, undergo meiosis, while somatic cells will undergo mitosis. After the cell proceeds successfully through the M phase, it may then undergo cell division through cytokinesis. The control of each checkpoint is controlled by cyclin and cyclin-dependent kinases. The progression of interphase is the result of the increased ...
As shown in the figure to the right, the periplasmic space in gram-negative or diderm bacteria is located between the inner and outer membrane of the cell. The periplasm contains peptidoglycan and the membranes that enclose the periplasmic space contain many integral membrane proteins, which can participate in cell signaling.