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  • regulation
  • In this thesis it is shown that by casting specific questions on the regulation and control of cell cycle transition points in the here extended framework of MCA, it is possible to derive consensus answers for subsets of mathematical models. (sun.ac.za)
  • ABSTRACT: We propose a protein interaction network for the regulation of DNA synthesis and mitosis that emphasizes the universality of the regulatory system among eukaryotic cells. (cellml.org)
  • The idiosyncrasies of cell cycle regulation in particular organisms can be attributed, we claim, to speci?c settings of rate constants in the dynamic network of chemical reactions. (cellml.org)
  • To support these claims, we convert the reaction mechanism into a set of governing kinetic equations and provide parameter values (specific to budding yeast, fission yeast, frog eggs, and mammalian cells) that account for many curious features of cell cycle regulation in these organisms. (cellml.org)
  • Our approach provides a theoretical framework in which to understand both the universality and particularity of cell cycle regulation, and to construct, in modular fashion, increasingly complex models of the networks controlling cell growth and division. (cellml.org)
  • The precise inheritance of genetic material in eukaryotes requires that initiation at each of the hundreds to thousands of replication origins be subject to exquisite regulation so that the DNA is duplicated exactly once per cell cycle. (grantome.com)
  • Specifically, we are interested in questions such as (i) what are the intracellular fluxes, (ii) what are the regulation mechanisms that a cell uses to control its metabolic fluxes, (iii) what are the principles underlying metabolism. (rug.nl)
  • In the last years, for example, we uncovered - first by computational predictions and later validated by experiments - that cells have mechanisms in place that sense metabolic flux and that are used for flux-dependent regulation. (rug.nl)
  • Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. (wikipedia.org)
  • Gene regulation may also serve as a substrate for evolutionary change, since control of the timing, location, and amount of gene expression can have a profound effect on the functions (actions) of the gene in a cell or in a multicellular organism. (wikipedia.org)
  • His research involves problems in cell and developmental biology, such as the dynamics and function of the cytoskeleton, the regulation of the cell cycle, and the process of signaling in embryos, as well as the evolution of the vertebrate body plan, and applying mathematical approaches to biology. (wikipedia.org)
  • 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 cycle. (wikipedia.org)
  • nuclei
  • However, this theory is controversial, and additional experimentation involving archaeal viruses is necessary, as they are probably the most evolutionarily similar to modern eukaryotic nuclei. (wikipedia.org)
  • Bacteria
  • Symbiosis between legumes and Rhizobium bacteria leads to the formation of root nodules where bacteria in the infected plant cells are converted into nitrogen-fixing bacteroids. (pnas.org)
  • In contrast, bacteroids in determinate nodules of the nongalegoid legumes lotus and bean are comparable to free-living bacteria in their genomic DNA content, cell size, and viability. (pnas.org)
  • The bacteria within the nodule cells gain the ability to fix nitrogen gas by means of their nitrogenase enzyme complex and supply the host plant with the reduced nitrogen for plant growth. (pnas.org)
  • Components of the citric acid cycle were derived from anaerobic bacteria, and the TCA cycle itself may have evolved more than once. (wikipedia.org)
  • organisms
  • The citric acid cycle (CAC) - also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle - is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into carbon dioxide and chemical energy in the form of adenosine triphosphate (ATP). (wikipedia.org)
  • All living organisms are products of repeated rounds of cell growth and division. (wikipedia.org)
  • Two research groups have produced several models of the cell cycle simulating several organisms. (wikipedia.org)
  • Biology
  • Marc W. Kirschner (born February 28, 1945) is an American cell biologist and biochemist and the founding chair of the Department of Systems Biology at Harvard Medical School. (wikipedia.org)
  • In 1993, he moved to Harvard Medical School, where he served as the chair of the new Department of Cell Biology for a decade. (wikipedia.org)
  • proliferation
  • Trichostatin A (TSA), isolated as a potent inducer of differentiation in murine erythroleukemia cells, caused reversible arrest of rat 3Y1 fibroblast proliferation in G1 and G2 phases without any inhibition of macromolecular synthesis. (springer.com)
  • Gelfant, S (1977) 'A new concept of tissue and tumor cell proliferation', Cancer Res. (springer.com)
  • It is hypothesized that the modern cell cycle, whereby mitosis, meiosis, and sex occur in all eukaryotes, evolved because of the balances struck by viruses, which characteristically follow a pattern of tradeoff between infecting as many hosts as possible and killing an individual host through viral proliferation. (wikipedia.org)
  • Nucleus
  • Viral eukaryogenesis is the hypothesis that the cell nucleus of eukaryotic life forms evolved from a large DNA virus in a form of endosymbiosis within a methanogenic archaeon. (wikipedia.org)
  • Further, the viral origins of the modern eukaryotic nucleus may have relied on multiple infections of archaeal cells carrying bacterial mitochondrial precursors with lysogenic viruses. (wikipedia.org)
  • The viral eukaryogenesis hypothesis depicts a model of eukaryotic evolution in which a virus, similar to a modern pox virus, evolved into a nucleus via gene acquisition from existing bacterial and archaeal species. (wikipedia.org)
  • control
  • The central question of this thesis focuses on quantifying the control in mathematical models of the G1/S transition by the individual cell cycle processes. (sun.ac.za)
  • The most important extension made it possible to follow and quantify, during a single cell cycle, the control properties of the individual system processes. (sun.ac.za)
  • Subsequently, these newly developed methods were used to determine the control by the individual processes of an important checkpoint in mammalian cells, the restriction point. (sun.ac.za)
  • Here is how the generic cell cycle control model looks like in the Model Builder. (vt.edu)
  • p34Cdc2 kinase family members are known to be essential for eukaryotic cell cycle control. (wikipedia.org)
  • Kirschner studies how cells divide, how they generate their shape, how they control their size, and how embryos develop. (wikipedia.org)
  • His lab is now a leader in using mathematical tools to analyze signaling pathways, cell size control, and the selectivity of drugs. (wikipedia.org)
  • Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell. (wikipedia.org)
  • He was awarded the 2001 Nobel Prize in Physiology or Medicine with Paul Nurse and Leland H. Hartwell for their discoveries of protein molecules that control the division of cells. (wikipedia.org)
  • Within the cell cycle, there is a stringent set of regulations known as the cell cycle control system that controls the timing and coordination of the phases to ensure a correct order of events. (wikipedia.org)
  • gene expression
  • In this hands-on activity students review the steps of eukaryotic gene expression and learn how this knowledge can be used to treat genetic disease. (hhmi.org)
  • Cellular Gene Expression Survey of PseudoRabies Virus (PRV) Infection of Human Embryonic Kidney Cells (HEK-293) , Veterinary Research. (irisa.fr)
  • meiosis
  • Meiosis is important to eukaryotes, such as plants, animals and fungi, because it is the method by which they produce sex cells. (reference.com)
  • The viral eukaryogenesis hypothesis points to the cell cycle of eukaryotes, particularly sex and meiosis, as evidence. (wikipedia.org)
  • Synthesis
  • DNA polymerases isolated from cells and artificial DNA primers can be used to initiate DNA synthesis at known sequences in a template DNA molecule. (wikipedia.org)
  • His PhD was supervised by Asher Korner and focused on haemoglobin synthesis in intact rabbit reticulocytes (immature red blood cells), and was awarded in 1968. (wikipedia.org)
  • The location provided a ready supply of surf clams and sea urchins amongst the reefs and fishing docks, and it was these invertebrates that were particularly useful for the study of the synthesis of proteins in embryogenesis, as the embryos were simply generated with the application of filtered sea water, and the transparency of the embryo cells was well suited to microscopic study. (wikipedia.org)
  • During G1 phase, the cell grows in size and synthesizes mRNA and proteins (Known as histones) that are required for DNA synthesis. (wikipedia.org)
  • In order for the cell to continue through the G1-pm, there must be a high amount of growth factors and a steady rate of protein synthesis, otherwise the cell will move into G0 phase. (wikipedia.org)
  • eukaryotes
  • This finding reveals a positive correlation in prokaryotes between DNA content and cell size, similar to that in eukaryotes. (pnas.org)
  • In the original paper it was also an RNA cell at the origin of eukaryotes, but eventually more complex, featuring RNA processing. (wikipedia.org)
  • mutations
  • This interactive focuses on the roles of germline and somatic cell mutations in human disease. (hhmi.org)
  • Interphase
  • Interphase ensures that the cell is the right size and has everything it needs to go through mitosis. (glogster.com)
  • Hunt found that cyclins begin to be synthesised after the eggs are fertilised and increase in levels during interphase, until they drop very quickly in the middle of mitosis in each cell division. (wikipedia.org)
  • In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. (wikipedia.org)
  • G1 phase ends when the cell moves into the S phase of interphase. (wikipedia.org)
  • G1 phase together with the S phase and G2 phase comprise the long growth period of the cell cycle called interphase that takes place before cell division in mitosis (M phase). (wikipedia.org)
  • checkpoints
  • The transition between these phases is regulated by so-called checkpoints, which are important to ensure proper functioning of the cell cycle. (sun.ac.za)
  • Explore the phases, checkpoints, and protein regulators of the cell cycle in this highly interactive Click and Learn and find out how mutated versions of these proteins can lead to the development of cancer. (hhmi.org)
  • progression of the cell
  • Some authors will say that the restriction point and the G1/S checkpoint are one and the same, but more recent studies have argued that there are two different points in the G1 phase that check the progression of the cell. (wikipedia.org)
  • transition
  • On the other hand, staurosporine, which we rediscovered as a new inhibitor of the cell cycle blocking Gl and G2, induced synchronous G2/M transition after release from the G2 arrest. (springer.com)
  • Such a checkpoint ensures that cells would have a critical mass at the G1/S transition point. (sun.ac.za)
  • induce cell
  • Nod factors induce cell divisions in the root cortex and successive divisions lead to the formation of the nodule primordium. (pnas.org)
  • Other mechanisms may include the activity of HDIs to induce cell differentiation, thus acting to "mature" some of the de-differentiated cells found in tumors. (wikipedia.org)
  • arrest
  • Cells released from the G2-arrest by both drugs entered a new S phase without passage through M phase, resulting in the formation of proliferative tetraploid cells. (springer.com)
  • species
  • The evolution of sexual reproduction describes how sexually reproducing animals, plants, fungi and protists evolved from a common ancestor that was a single celled eukaryotic species. (wikipedia.org)
  • model
  • This CellML model represents the mammalian cell model taken from the original model code. (cellml.org)
  • In studies at UC San Francisco of the frog embryo as a model system of cell development, Kirschner identified the first inducer of embryonic differentiation, fibroblast growth factor (FGF), an early finding in the field of signal transduction. (wikipedia.org)
  • The complex network of biochemical reaction/transport processes and their spatial organization make the development of a predictive model of a living cell a grand challenge for the 21st century. (wikipedia.org)
  • this type of model is called a deterministic process (whereas a model describing a statistical distribution of protein concentrations in a population of cells is called a stochastic process). (wikipedia.org)
  • interactions
  • The importance of proteolytic degradation in eukaryotic cell cycle changed the view of cell division as a simple kinase cascade to a more complex process in which interactions among phosphorylation, ubiquitination, and proteolysis are necessary. (wikipedia.org)
  • bacterial cell
  • Plant factors present in nodules of galegoid legumes but absent from nodules of nongalegoid legumes block bacterial cell division and trigger endoreduplication cycles, thereby forcing the endosymbionts toward a terminally differentiated state. (pnas.org)
  • and another prokaryotic (bacterial) cell that, by endocytosis, became the modern mitochondrion or chloroplast. (wikipedia.org)
  • Oxidative Phosphorylation
  • The NADH generated by the citric acid cycle is fed into the oxidative phosphorylation (electron transport) pathway. (wikipedia.org)
  • The NADH and FADH2 generated by the citric acid cycle are, in turn, used by the oxidative phosphorylation pathway to generate energy-rich ATP. (wikipedia.org)
  • restriction point
  • The G1 checkpoint, also known as the restriction point in mammalian cells and the start point in yeast, is the point at which the cell becomes committed to entering the cell cycle. (wikipedia.org)
  • As the cell progresses through G1, depending on internal and external conditions, it can either delay G1, enter a quiescent state known as G0, or proceed past the restriction point. (wikipedia.org)
  • The restriction point (R) in the G1 phase is different from a checkpoint because it does not determine whether cell conditions are ideal to move on to the next phase, but it changes the course of the cell. (wikipedia.org)
  • After a vertebrate cell has been in the G1 phase for about three hours, the cell enters a restriction point in which it is decided whether the cell will move forward with the G1 phase or move into the dormant G0 phase. (wikipedia.org)
  • The first restriction point is growth-factor dependent and determines whether the cell moves into the G0 phase, while the second checkpoint is nutritionally-dependent and determines whether the cell moves into the S phase. (wikipedia.org)
  • dynamical
  • Traditionally, models for biological systems that show rich dynamic behavior, such as the cell cycle, are studied using dynamical systems analysis. (sun.ac.za)
  • Cell Collective is a modeling software that enables one to house dynamical biological data, build computational models, stimulate, break and recreate models. (wikipedia.org)
  • Cellular
  • Cellular respiration, with a series of steps and intracellular functions, is the method used by cells to release energy from chemical bonds of molecules, s. (reference.com)
  • differentiation
  • Here we demonstrate that differentiation of bacteroids in indeterminate nodules of Medicago and related legumes from the galegoid clade shows remarkable similarity to host cell differentiation. (pnas.org)
  • These postmitotic cells are unable to divide and enter the nodule differentiation program. (pnas.org)
  • division
  • ENGLISH ABSTRACT: The multiplication of cells proceeds through consecutive phases of growth and division (G1, S, G2 and M phases), in a process known as the cell cycle. (sun.ac.za)
  • This may be because of the cell division event which we are currently unable to express in CellML. (cellml.org)
  • In the case of determinate nodules, the initial cell division activity required for nodule primordium formation ceases rapidly and therefore the determinate nodules contain no meristem. (pnas.org)
  • Cyclins are proteins that play a key role in regulating the cell-division cycle. (wikipedia.org)
  • In humans, the normal physiological temperature is around 37 °C (98.6 °F). G1 phase is particularly important in the cell cycle because it determines whether a cell commits to division or to leaving the cell cycle. (wikipedia.org)
  • HeLa
  • Recent evidence (preprinted at BioRxiv) suggests widespread human protein phosphorylation on multiple non-canonical amino acids, including motifs containing phosphorylated histidine, aspartate, glutamate, arginine and lysine in HeLa cell extracts. (wikipedia.org)
  • endocytosis
  • Rhizobia are released from infection threads in the cytoplasm of postmitotic nondividing cells by endocytosis. (pnas.org)