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Apr 2, 2013 · Cell Biochemistry & Function; Drug Development Research; ... The present study describes the synthesis of three substituted 1-(1-phenylcyclohexyl)piperidines, (3-MeO ...
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Cell Biochemistry & Function; Drug Development Research;...
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Drug Testing and Analysis is a specialist journal covering...
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- Overview
- Introduction
- Stages of the cell cycle
- Interphase
- M phase
- Cell cycle exit and G0
- How long does the cell cycle take?
The cell cycle is composed of interphase (G₁, S, and G₂ phases), followed by the mitotic phase (mitosis and cytokinesis), and G₀ phase.
Have you ever watched a caterpillar turn into a butterfly? If so, you’re probably familiar with the idea of a life cycle. Butterflies go through some fairly spectacular life cycle transitions—turning from something that looks like a worm into a pupa, and finally into a glorious creature that floats on the breeze. Other organisms, from humans to plants to bacteria, also have a life cycle: a series of developmental steps that an individual goes through from the time it is born until the time it reproduces.
The cell cycle can be thought of as the life cycle of a cell. In other words, it is the series of growth and development steps a cell undergoes between its “birth”—formation by the division of a mother cell—and reproduction—division to make two new daughter cells.
To divide, a cell must complete several important tasks: it must grow, copy its genetic material (DNA), and physically split into two daughter cells. Cells perform these tasks in an organized, predictable series of steps that make up the cell cycle. The cell cycle is a cycle, rather than a linear pathway, because at the end of each go-round, the two daughter cells can start the exact same process over again from the beginning.
In eukaryotic cells, or cells with a nucleus, the stages of the cell cycle are divided into two major phases: interphase and the mitotic (M) phase.
•During interphase, the cell grows and makes a copy of its DNA.
•During the mitotic (M) phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells.
Let’s enter the cell cycle just as a cell forms, by division of its mother cell. What must this newborn cell do next if it wants to go on and divide itself? Preparation for division happens in three steps:
•G1 phase. During G1 phase, also called the first gap phase, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps.
[Do cells always grow before they divide?]
•S phase. In S phase, the cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome. The centrosomes help separate DNA during M phase.
•G2 phase. During the second gap phase, or G2 phase, the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis. G2 phase ends when mitosis begins.
The G1 , S, and G2 phases together are known as interphase. The prefix inter- means between, reflecting that interphase takes place between one mitotic (M) phase and the next.
During the mitotic (M) phase, the cell divides its copied DNA and cytoplasm to make two new cells. M phase involves two distinct division-related processes: mitosis and cytokinesis.
In mitosis, the nuclear DNA of the cell condenses into visible chromosomes and is pulled apart by the mitotic spindle, a specialized structure made out of microtubules. Mitosis takes place in four stages: prophase (sometimes divided into early prophase and prometaphase), metaphase, anaphase, and telophase. You can learn more about these stages in the video on mitosis.
In cytokinesis, the cytoplasm of the cell is split in two, making two new cells. Cytokinesis usually begins just as mitosis is ending, with a little overlap. Importantly, cytokinesis takes place differently in animal and plant cells.
•In animals, cell division occurs when a band of cytoskeletal fibers called the contractile ring contracts inward and pinches the cell in two, a process called contractile cytokinesis. The indentation produced as the ring contracts inward is called the cleavage furrow. Animal cells can be pinched in two because they’re relatively soft and squishy.
What happens to the two daughter cells produced in one round of the cell cycle? This depends on what type of cells they are. Some types of cells divide rapidly, and in these cases, the daughter cells may immediately undergo another round of cell division. For instance, many cell types in an early embryo divide rapidly, and so do cells in a tumor.
Other types of cells divide slowly or not at all. These cells may exit the G1 phase and enter a resting state called G0 phase. In G0 , a cell is not actively preparing to divide, it’s just doing its job. For instance, it might conduct signals as a neuron (like the one in the drawing below) or store carbohydrates as a liver cell. G0 is a permanent state for some cells, while others may re-start division if they get the right signals.
Different cells take different lengths of time to complete the cell cycle. A typical human cell might take about 24 hours to divide, but fast-cycling mammalian cells, like the ones that line the intestine, can complete a cycle every 9-10 hours when they're grown in culture1,2 .
Different types of cells also split their time between cell cycle phases in different ways. In early frog embryos, for example, cells spend almost no time in G1 and G2 and instead rapidly cycle between S and M phases—resulting in the division of one big cell, the zygote, into many smaller cells2,3 . Click here to see a cool, sped-up video of dividing frog embryos.
Jan 1, 2016 · The first arylcyclohexamine to be described was 1-(1-phenylcyclohexyl) amine, in 1907, almost 50 years before the synthesis of PCP . Other analogues reported in the early 1950s included N-ethyl-1-phenylcyclohexylamine (PCE) and 1-(1-phenylcyclohexyl)morpholine (PCMo). While many were not explored further by their initial investigators, chemists ...
Learning Objectives. The cell cycle is an ordered series of events involving cell growth and cell division that produces two new daughter cells. Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages of growth, DNA replication, and division that produce two genetically identical cells.
Various 1-arylcyclohexylamines were synthesized for evaluation as central nervous system depressants and tested for cataleptoid activity and antitonic extensor properties. Various 1-arylcyclohexylamines were synthesized for evaluation as central nervous system depressants. The compounds were prepared by several procedures. 1-(1-Phenylcyclohexyl)piperidine, the first compound of this type ...
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Jul 30, 2022 · Just as the cell’s genome describes its full complement of DNA, a cell’s proteome is its full complement of proteins. Protein synthesis begins with genes. A gene is a functional segment of DNA that provides the genetic information necessary to build a protein. Each particular gene provides the code necessary to construct a particular protein.
The formation of all metabolites requires microsomal enzymes, but VII and the previously described N-(5-hydroxypentyl)-1-phenylcyclohexylamine, VI, also require soluble enzymes. Quantitative or semiquantitative data show that VI and VIII appear and disappear with time, whereas VII seems to be a terminal metabolite.
