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The study of the cell cycle focuses on mechanisms that regulate the timing and frequency of DNA duplication and cell division. As a biological concept, the cell cycle is defined as the period between successive divisions of a cell. During this period, the contents of the cell must be accurately replicated. Microscopists had known about cell division for more than one hundred years, but not until the 1950s, through the pioneering work of Alma Howard and Stephen Pelc, did they become aware that DNA replication took place only at a specific phase of the cell cycle and that this phase was clearly separated from mitosis. Howard and Pelc's work in the broad bean, Vicia faba, revealed that the cell goes through many discrete phases before and after cell division. From this understanding, scientists then identified the four characteristic phases of the cell cycle: mitosis (M), gap 1 (G1), DNA synthesis (S), and gap 2 (G2). The study of these phases, the proteins that regulate them, and the complex biochemical interactions that stop or start DNA replication and cell division (cytokinesis) are the primary concerns of cell cycle biologists.
The most significant progress in this research field came with the demonstration that specific protein complexes involving cyclins were critical for regulating the passage of cells through the cell cycle. These early observations came from biological studies of the cells of rapidly dividing fertilized frog eggs as well as mutant yeast cells that could not divide. The observations suggested that regulation of the cell cycle is conserved throughout eukaryotes, which has since proved to be the case. The mechanism of division in bacteria differs from that of eukaryotes, and the control of their cell cycle is also somewhat different, although again it is linked with DNA replication.
Although the cell cycle is a highly integrated process, distinct areas of interest within this field of study have emerged. For instance, many genes and proteins that influence the passage from one phase of the cell cycle to another have been identified. When their expression is altered by mutation or aberrant regulation, they are usually classed as oncogenes. Other proteins act to hold the cell at distinct points in the cycle (checkpoints) and are known as tumor suppressor genes. Apart from those with a clearly regulatory role, many proteins have important functions in other aspects of the cell cycle; one is replication of DNA and organelles, which is a fascinating process that includes its own repair mechanisms and self-editing. Other fields focus primarily on the mechanical processes of cell cleavage into two daughter cells at the end of mitosis and on the condensation and decondensation of chromatin.
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I believe the best option would be letter C) Diphtheria is never allowed to talk to typhoid and visa versa.
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"Angela's Ashes" is a memoir written by Irish author Frank McCourt. The book is known to be filled with humor and anecdotes of McCourt's childhood.
At a certain point, Frank is hospitalized. But, due to his love of literature, he is constantly trying to communicate with Patricia. She is at the hospital too, and she has books with poems that delight Frank. When he is about to find out what happened to the Highwayman and his lover, the nurse comes in and yells, "I told ye there was to be no talking between rooms. Diphtheria is never allowed to talk to typhoid and visa versa." This line is quite humorous for the way it addresses people and diseases. It's as if people stopped being people and became the disease they had. Diseases don't talk; sick people do. But not to the nurse's eyes.
The sieve filters the sand and you get resources out of it.
Depends on what kind of essay, comment me back and tell what kind.
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https://quizlet.com/176236716/vma-laws-and-ethics-flash-cards/
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