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The main mechanism of action of the cell cycle checkpoints is through the regulation of the activities of a family of protein kinases known as the cyclin-dependent kinases (CDKs), which bind to different classes of regulator proteins known as cyclins, with specific cyclin-CDK complexes being formed and activated at different phases of the cell ...
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.
They can also be converted into glucose. [4] This glucose can then be converted to triglycerides and stored in fat cells. [5] Proteins can be broken down by enzymes known as peptidases or can break down as a result of denaturation. Proteins can denature in environmental conditions the protein is not made for. [6]
The protons return to the mitochondrial matrix through the protein ATP synthase. The energy is used in order to rotate ATP synthase which facilitates the passage of a proton, producing ATP. A pH difference between the matrix and intermembrane space creates an electrochemical gradient by which ATP synthase can pass a proton into the matrix ...
Proteolysis of the zymogen yields an active protein; for example, when trypsinogen is cleaved to form trypsin, a slight rearrangement of the protein structure that completes the active site of the protease occurs, thereby activating the protein. Proteolysis can, therefore, be a method of regulating biological processes by turning inactive ...
The cell on the left is going through mitosis and its chromosomes have condensed. Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis (transcription) occur.
For example, Cdk, or cyclin dependent kinase, is a major control switch for the cell cycle and it allows the cell to move from G1 to S or G2 to M by adding phosphate to protein substrates. Such multi-component (involving multiple inter-linked proteins) switches have been shown to generate decisive, robust (and potentially irreversible ...
In eukaryotes, these redox reactions are catalyzed by a series of protein complexes within the inner membrane of the cell's mitochondria, whereas, in prokaryotes, these proteins are located in the cell's outer membrane. These linked sets of proteins are called the electron transport chain. In eukaryotes, five main protein complexes are involved ...