during a mitotically active cell cycle, when does DNA replication occur?
478358
In the S phase, which is between the G1 and G2 Phase
866207
the cell dividing force lol. theres no such force. it's a spontaneous occurence
339071
Mitosis, also called karyokinesis, is division of the nucleus and its chromosomes.  It is followed by division of the cytoplasm known as cytokinesis.  Both mitosis and cytokinesis are parts of the life of a cell called the Cell Cycle.  Most of the life of a cell is spent in a non-dividing phase called Interphase.  Interphase includes G1 stage in which the newly divided cells grow in size, S stage in which the number of chromosomes is doubled and appear as chromatin, and G2 stage where the cell makes the enzymes & other cellular materials needed for mitosis.\n\nMitosis has 4 major stages --- Prophase, Metaphase, Anaphase, and Telophase. When a living organism needs new cells to repair damage, grow, or just maintain its condition, cells undergo mitosis.\n\nDuring Prophase, the DNA and proteins start to condense. The two centrioles move toward the opposite end of the cell in animals or microtubules are assembled in plants to form a spindle. The nuclear envelope and nucleolus also start to break up.\n\n\nProphase\n\nDuring Metaphase, the spindle apparatus attaches to sister chromatids of each chromosome. All the chromosomes are line up at the equator of the spindle. They are now in their most tightly condensed form.\n\n\nMetaphase\n\nDuring Anaphase, the spindle fibers attached to the two sister chromatids of each chromosome contract and separate chromosomes which move to opposite poles of the cell.\n\n\nAnaphase\nIn Telophase, as the 2 new cells pinch in half (animal cells) or a cell plate forms (plant cells), the chromosomes become less condensed again and reappear as chromatin. New membrane forms nuclear envelopes and the nucleolus is reformed.
258433
mitosis is asexual reproduction, cells divide and reproduce replicating their own DNA exactly\n\nmeiosis is sexual reproduction, new cells contain only half of their original DNA, and half from a different parent source
886886
yes [by mitosis];\nsometimes; \nsometimes, depending on the genes affected\n\nlearn about DNA and MITOSIS @:\n\nhttp://en.wikipedia.org/wiki/Dna\nhttp://en.wikipedia.org/wiki/Mitosis
918391
When cells prepare for mitosis their DNA strands twist together more and shorten enough to be seen under a microscope.  During normal interphase the DNA is unraveled and working, so the strands appear longer and thinner.  Most microscope cannot allow you to see these thin strands.
765843
There is a very cool way to demonstrate the S phase of the cell cycle.  There is a chemical compound BrdU (Bromodioxy uridine) that can act as a replacement for genetic thymadine.  If you inject the animal undergoing S phase with Brdu, it will be incorporated into the replicated DNA.  You can then label that chemical with either Immunofluorescence or Immunohistochemical reagents that will either make the label visible because it fluoresces under specific light conditions or will stain a dark color and be visible in a light microscope.
800985
When cells want to reproduce, they douplicate thier dna, then each identicle set of dna move to separate ends of the cell and the cell begins to pinch together in the middle to divide the cytoplasm (the stuff that fills the cells) in two, creating two identicle cells to the original cell, each with their own set of dna. This process is called mitosis.
142630
S phase is the period of synthesis.  Mitosis is the nuclear division phase. If mitosis occur before DNA duplication during  anaphase or nuclear division results imbalance chromosome number. There is also some regulatory mechanism that copletion of DNA synthesis stimulates the mitosis to occur.
506224
Both involve prophase, metaphase, anaphase and telophase. Both involve cytokinesis, and lastly DNA is replicated just before cells enter either mitosis or meiosis.
454835
that mitosis or meiosis occured.
773929
(for animal cells..)\n1. non-kinetochore microtubules lengthen. this elongates the cell even more than before.\n2. pairs of sister chromosomes attach at opposite ends of the cell.\n3. new nuclear envelopes form around the two sets of dna at the opposite ends of the cell.\n4. cytokinesis (division of cytoplasm) occurs and the plasma membrane re-forms around the two daughter cells.
912340
There is only one DNA replication, as the ending 4 cells all have only half the number of chromosomes (haploid number)
128363
Could be one of two things:\n\n1) a portion of the DNA is replicated so that it can be towed out of the nucleus and used to direct cellular activities.\n\n2) the entire strand of DNA is replicated at the beginning of cellular division, with one copy going to each new cell.
233562
mitosis:the process in cell division by which the nucleus divides, typically consisting of four stages: prophase, metaphase, anaphase and telophase.\n\nmeiosis: (genetics) cell division that produces reproductive cells in sexually reproducing organisms; the nucleus divides into four nuclei each containing half the chromosome number (leading to gametes in animals and spores in plants) \n\nosmosis:Transmission of fluids from one cell into another; foundation of metabolism, led by the concentration of salt within a cell. Water can penetrate cell membranes, and strives to, where the concentration of salt is highest, in order to equalize the salt concentration in the body.
1098076
A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. During either process, the word "chromosome" indicates a pair of two exactly identical ("sister") chromatids joined at the central point of each chromatid, called the centromere.\n\nA chromosome, by definition, has exactly one centromere. Thus when sister chromatids are pulled apart by the mitotic spindle during anaphase -- that is, when the centromere joining two sister chromatids splits into two centromeres -- then each sister chromatid becomes an independent chromosome.\n\nIn non-gametic, non-dividing human cells, there are 23 pairs of chromosomes, thus 46 chromatids. When it is ready for mitotic cell division, each chromosome will replicate itself during the synthesis phase within its life cycle, making a total of 92 chromatids before dividing, producing two cells each with 46 (remember, since the term "chromosome" is redefined,but still the number of chromosomes remains 46 despite the replication).\n\nIn gametic cell division (meiosis),the cell replicates once but divides twice so that 23 chromosomes are left in each of four egg or sperm cells. (23 chromosomes are each needed from the male and female to combine and make 46 chromosomes for the zygote.)\n\nA common mistake among students is that they think that chromatids always exist; chromatids ONLY exist when a chromosome replicates itself.
264517
Meiosis, as the name implies is a reduction division. That is at the end of it the chromosome number is reduced to half the original number; from diploid to haploid.\nThus, it can occur only in diploid cells, haploid can never undergo meiosis.\nIt occurs during gamete formation, spore formation or zygote germination. It is the nature’s mechanism by means of which the chromosome number and the quantity of DNA remains constant from one generation to the next.\n What happens before meiosis? – Chromosome duplication occurs before the cell begins to divide; the DNA content of the nucleus doubles.\nWhat is produced after the first division? – Two daughter nuclei are produced at the end of it. The chromosome number is reduced to half in each one of them; i.e. they are, now, haploid. But the DNA content is not exactly halved. \nWhat is produced after the second division? - The second meiotic division is the same as mitosis. From two daughter nuclei in the earlier phase four daughter nuclei are produced. The chromosome number is already reduced, now the DNA quantity is also reduced to half of that present in the original parental cell.\nThus the four cells at the end of meiosis are haploid and DNA is also half of the original parental cell. Thus the products are different than the one at the end of mitosis. Besides, the genes are also different and not identical on all the four cells.  \n What can go wrong? – Many things can go wrong and it will be difficult to explain them here.\n1) Chromosome pairs may fail to separate properly, leading to chromosomal imbalance in the resulting cell. This in turn can produce genetic defects or variations in the next generation.