What is the step that happens in prophase II?
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the chromosomes group together.
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Mitosis\n\nThe beginning of mitosis is called prophase. In early prophase, the centrosomes move toward opposite poles of the cell, organizing the spindle microtubules between them. The sister chromatids become visible in the nucleus as they condense. \n\nIn late prophase, the nuclear membrane breaks down and some of the spindle microtubules attach to the sister chromatids. The microtubules pull the chromatid pairs to the midline of the cell, or metaphase plate.\n\n•••\n\nThe chromatids remain lined up between the poles of the cell during metaphase.\n\n•••\n\nAnaphase begins when the pairs of sister chromatids separate. The separated chromatids are now called chromosomes, and move toward the poles of the cell.\n\n•••\n\nThe chromosomes arrive at the poles in telophase, and new nuclear membranes form around them.\n\n•••\n\nDivision of the cytoplasmic components is called cytokinesis. \n\nIn animal cells, cytokinesis occurs when a ring of actin and myosin filaments constricts the plasma membrane at the equator. Eventually, the parent cell is divided into two cells.\n\nAnimal Cytokinesis Movie (500K)\n\n\n\nIn plant cells, a number of small vesicles fuse at the metaphase plate to form the cell plate. Over time, the cell plate reaches across the cell and joins with the plasma membrane.\n\n•••\n\nThe process of mitosis and cytokinesis creates two separate cells, each with an identical set of chromosomes. After cytokinesis, the daughter cells will enter interphase.
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gametophye (haploid)--*mitosis*-->gametes (haploid)--*fertilization-->zygote (diploid)--*mitosis*-->sporophyte (diploid)--*meiosis*-->spores (haploid)\n\nand then you're back to gametophyte again...This is "alternation of generations," it's cyclical. *denote a process*
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telophase...it's basically the reverse of prophase.
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ur question should be under biology but still, mitosis is the process of when the cells split to create 4 indentical cells during mitosis, one copy of the dna is distributed into each of the tow daughter cells mitosis id divided into 4 interphases: prophase, metaphase, anaphase, and telophase. in prophase, the chromatin in the nucleus condenses to form chorosomes. structures celled spindle fibers form a bridge between the ends of the cell. the nuclear membrane breaks down. in metaphase, the chromosomes line up across the center of the cell. each chromosome attaches to a spindle fiber at its centromere, which still holds the chromatids together. in anaphase, the centromeres split. the two chromatids separate. one chromatid moves along the spindle fiber to one end of the cell. the other chromatid moves to the opposite end. the cell becomes stretched out as the opposite ends pull apart. in telophase, the chromosomes begin to stretch out and lose their rodlike appearance. this occurs in the two regions at the ends of the cell. a new nuclear membrane forms around each region of chromosomes. o yeah and btw mitosis is on stage of the cell cycle there are like 2 before it and 1 after it
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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.
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It is called mitosis and the stage where you could see pairs of doublestranded chromos. would be in Prophase.
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remember the phases in meiosis (in order) :Prophase, Metaphase, anaphase, telephase (pmat)\nMitosis\nI  INTRODUCTION \n\nMitosis, process in which a cell’s nucleus replicates and divides in preparation for division of the cell. Mitosis results in two cells that are genetically identical, a necessary condition for the normal functioning of virtually all cells. Mitosis is vital for growth; for repair and replacement of damaged or worn out cells; and for asexual reproduction, or reproduction without eggs and sperm.\n\nAll multicellular animals, plants, fungi, and protists, which begin life as single cells, carry out mitosis to develop into complex organisms containing billions of cells. Mitosis continues in full-grown organisms as a means of maintaining the organism—replacing dying skin cells, for example, or repairing damaged muscle cells. In the cells of the adult human body, mitosis occurs about 25 million times per second. Multicellular organisms such as sea stars, sea anemones, fungi, and certain plants rely on mitosis for asexual reproduction at particular stages in their life cycles, and mitosis is the sole mode of reproduction for many single-celled organisms.\n\nII  INTERPHASE \n\nThe life cycle of eukaryotic cells, or cells containing a nucleus, is a continuous process typically divided into three phases for ease of understanding: interphase, mitosis, and cytokinesis. Interphase includes three stages, referred to as G1, S and G2. In G1, a newly formed cell synthesizes materials needed for cell growth. In the S stage, deoxyribonucleic acid (DNA), the genetic material of the cell, is replicated. At this stage, DNA consists of long, thin strands called chromatin. As each strand is replicated, it is linked to its duplicate by a structure known as a centromere. When the S stage is complete, the cell enters a brief stage known as G2, when specialized enzymes correct any errors in the newly synthesized DNA, and proteins involved with the next phase, mitosis, are synthesized. \n\nIII  MITOSIS \n\nMitosis occurs in four steps. In prophase the replicated, linked DNA strands slowly wrap around proteins that in turn coil and condense into two short, thick, rodlike structures called chromatids, attached by the centromere. Two structures called centrioles, both located on one side of the nucleus, separate and move toward opposite poles of the cell. As the centrioles move apart, they begin to radiate thin, hollow, proteins called microtubules. The microtubules arrange themselves in the shape of a football, or spindle, that spans the cell, with the widest part at the center of the cell and the narrower ends at opposite poles. As the spindle forms, the nuclear membrane breaks down into tiny sacs or vesicles that are dispersed in the cytoplasm. Final disintegration of the membrane marks the beginning of metaphase. \n\nIn metaphase, the spindle fibers attach to the chromatids near the centromeres, and tug and push the chromatids so that they line up in the equatorial plane of the cell halfway between the poles. Like two individuals standing back to back at the equator, one chromatid faces one pole of the cell, and its linked partner faces the opposite pole. This precise orientation is necessary in order for the next step, anaphase, to occur. Anaphase begins when the centromeres split, separating the identical chromatids into single chromosomes, which then move along the spindle fibers to opposite poles of the cell. \n\nAs these two identical groups of single chromosomes gather at opposite poles of the cell, telophase begins. A new nuclear membrane forms around each new group of chromosomes. The spindle fibers break down and the newly formed chromosomes begin to unwind. If viewed under a light microscope, the chromosomes appear to fade away. They exist, however, in the form of chromatin, the extended, thin strands of DNA too fine to be seen except with electron microscopes. Mitosis accomplishes replication and division of the nucleus,
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DNA replication or DNA synthesis, it is the process of copying a double-stranded DNA strand. Since DNA strands are antiparallel and complementary, each strand can serve as a template for the reproduction of the opposite strand. The template strand is preserved as a whole piece and the new strand is assembled from nucleotide triphosphates. This process is called semiconservative replication. Ideally, the two resulting strands are identical, although in reality there are always errors, though proofreading and error-checking mechanisms exist to ensure a very high level of fidelity.\n\nIn a cell, this step is obligatory prior to cell division. Prokaryotes persistently replicate their DNA and creating a whole, new chromosome is a limiting step in cell division. In eukaryotes, timings are highly regulated and this occurs during the S phase of the cell cycle, preceding mitosis or meiosis I. \n\n\nIf you were to decide to physically “snip” a eukaryotic cell into two halves, it is certain that all of the components you need to allow each half to live and survive would be present in each half – each new cell, EXCEPT for the genetic material, the DNA in the chromosomes. It is a virtual certainty that any attempt to simply physically partition a cell that way would fail to give each new cell the correct genetic complement. That is why a cell undergoes mitosis when it divides asexually, the process of mitosis is essential, it causes each new cell to have a complete set of all of the chromosomes needed to survive and reproduce.
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Yes. At Metaphase the chromosomes line up on a central axis, then during Anaphase, they separate
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Stages of Interphase\n\n    * G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.\n\n    * S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.\n\n    * G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.\n\n    * In the latter part of interphase, the cell still has nucleoli present.\n\n    * The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin.\n\n    * In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus.
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This may seem like a silly suggestion, but try representing the elements mentioned in your textbook (which I'm sure has some illustrations) with pieces of paper, matches, beans or something like that, so you can understand the events and the outcome. \nNow, if you _really_ want an explanation, here it comes (I've ommited the names of the phases, they'll be in your textbook).\n\nMeiosis includes 2 cell divisions with different characteristics. \nWe start with a diploid (2 n) cell, in which DNA duplication has occurred so that each DNA strand is double. These strands do not yet appear as chromosomes (condensed bodies); in fact, the chromatin strands have to be "relaxed" in order to duplicate. \n\n***Meiosis I: (in which the nº of chromosomes decreases to half)\n1. The chromatin (DNA strands) starts to condense and appears as small dense dots (the chromosomes) within the cell nucleus. These chromosomes will each have 2 "arms" (they look like an X or a V) because the DNA in each has been duplicated.\n2. Now all these chromosomes align in homologous pairs, with the aid of a transparent structure formed by tiny intracellular fibers (the spindle) that has formed and will help them to move in orderly fashion within the nucleus.\n3. While they keep condensing, each homologous chromosome contacts its "brother", and they exchange some fragments of their DNA ("crossing over"). Usually only one "arm" of each  chromosome participates in crossing over. \n4. In the meantime, the nuclear membrane is disintegrating...\n5. The pairs of homologues, still united, align at the middle (equator) of the spindle... \n6... and then each pair of homologues is divided, one chromosome of each pair goes toward each "pole" of the spindle. \n7. New nuclear membranes form around the 2 groups of chromosomes. Each of these groups will only have ONE of each pair of homologues. Essentially the information in each new nucleus is the same, BUT has some differences because, as you recall, there has been crossing over i.e. partial exchange of DNA between homologues. \n8. The original cell with the 2 nuclei divides and forms 2 cells, with half the nº of chromosomes of the original cell (haploid or n). Each of the chromosomes still has a duplicate DNA strand.\n\n... the cell takes a short break (you can take a break too!)... but the chromatin does not duplicate this time (it's already done that)\n\n***Meiosis II: (in which each double DNA strand becomes single again, this phase is similar to a normal mitosis).\n1. The chromatin condenses again, so that it appears as chromosomes.\n2. This time the spindle aligns the center of each chromosome at its equator.\n3. The central part of the chromosome is duplicated and the sister "arms" (chromatids) separate, each migrating to opposite poles.\n4. Now you have two groups of chromosomes, each group still has the haploid (n) nº of chromosomes (the same amount with which they started this 2nd meiosis) but now, each chromosome has a single DNA strand. \nA new nuclear membrane forms around each of these groups of chromosomes.\n5. The rest of the cell divides.\n\nSo, to sum up: you started with ONE diploid cell. You end with FOUR haploid cells. In animals, this process only happens during the production of gametes. \nIf we're talking about the formation of female gametes, then only ONE of the 4 resulting cells will become an ovule (and that only after more maturation), the other 3 cells form "polar bodies".\nIn contrast, when it's spermatozoids being produced, all FOUR resulting cells will become spermatozoids. \nThat's one of the reasons sperm is cheaper than ovules! There's just more of them in the entire animal kingdom.\n\nNow, what is the purpose of this extremely complicated (the above is a very simplified version) process? The result will be cells that have half the chromosomes of the normal body cells. These cells
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mitosis is not the 2nd part of meiosis. \ncrossing over does not happen in mitosis basically because there is no need to do so. \ncrossing over occurs in the 1st part of meiosis  when the 2 pairs of homologous chromosomes come together in the prophase part of meiosis--one pair of chromosomes from each parent. that is where the exhcange of genes occur in order to add variation between the 4 daughter cells.\nin mitosis, the homologous chromosomes do not come together. the DNA simply copies itself and will eventually lead to the split into 2 identical daughter cells.
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During prophase. But it actually doesn't happen in all organisms. Yeast for example has a nuclear duplication and division without ever breaking down the nuclear membrane.
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The beginning of somatic cell division or mitosis is called prophase. In early prophase, the centrosomes move toward opposite poles of the cell, organizing the spindle microtubules between them. The sister chromatids become visible in the nucleus as they condense.In late prophase, the nuclear membrane breaks down and some of the spindle microtubules attach to the sister chromatids. The microtubules pull the chromatid pairs to the midline of the cell, or metaphase plate.The chromatids remain lined up between the poles of the cell during metaphase.Anaphase begins when the pairs of sister chromatids separate. The separated chromatids are now called chromosomes, and move toward the poles of the cell.The chromosomes arrive at the poles in telophase, and new nuclear membranes form around them.Division of the cytoplasmic components is called cytokinesis.In animal cells, cytokinesis occurs when a ring of actin and myosin filaments constricts the plasma membrane at the equator. Eventually, the parent cell is divided into two cells.Meiosis I-Prophase I-In the leptotene stage, the cell's genetic material, which is normally in a loosely arranged pile known as chromatin, condenses into visible threadlike structures. Along the thread, centromeres are visible as small beads of tightly coiled chromatin. Recall that centromeres are connection sites between sister chromatids, which are not yet distinguishable. As the chromatin becomes progressively ordered and visible, homologous chromosomes find each other and bind together. In this process, called synapsis, a protein structure called the synaptonemal complex attaches the homologous chromosomes tightly together all along their lengths.The zygotene stage sees the completion of synapsis. The paired homologous chromosomes are said to be bivalent. They may also be referred to as a tetrad, a reference to the four sister chromatids. During this stage, one percent of DNA that wasn't replicated during S phase is replicated. The significance of this cleanup act is unclear.The pachytene stage heralds crossing over. Nonsister chromatids of homologous chromosomes exchange segments of genetic information. Because the chromosomes cannot be distinguished in the synaptonemal complex, the actual act of crossing over is not perceivable through the microscope.During the diplotene stage, the synaptonemal complex degrades. Homologous chromosomes fall apart and begin to repel each other. The chromosomes themselves uncoil a bit, allowing some transcription of DNA. They are held together by virtue of recombination nodules, betraying the sites of previous crossing over, the chiasmata.Chromosomes recondense during the diakinesis stage. Sites of crossing over entangle together, effectively overlapping, making chiasmata clearly visible. In general, every chromosome will have crossed over at least once. The nucleoli disappears and the nuclear membrane disintegrates into vesicles.During these stages, centrioles are migrating to the two poles of the cell. These centrioles, which were duplicated during interphase, function as microtubule coordinating centers. Centrioles sprout microtubules, essentially cellular ropes and poles, during crossing over. They invade the nuclear membrane after it disintegrates, attaching to the chromosomes at the kinetochore. The kinetochore functions as a motor, pulling the chromosome along the attached microtubule toward the originating centriole, like a train on a track. There are two kinetochores on each tetrad, one for each centrosome. Prophase I is the longest phase in meiosis.Microtubules that attach to the kinetochores are known as kinetochore microtubules. Other microtubules will interact with microtubules from the opposite centriole. These are called nonkinetochore microtubules.Metaphase I-As kinetochore microtubules from both centrioles attach to their respective kinetochores, the homologous chromosomes align equidistant above and below an imaginary equatorial plane, due to cont
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Mitosis and meiosis are sometimes called the two "nuclear division" processes
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none\n\n\nyou start with one pair of homologous chromosomes in prophase I of meiosis I.  at metaphase I, these homologues line up across the metaphase plate, and at anaphase, they seperate so that one homologue goes to one pole, and the other homologue goes to the other pole.  after cytokinesis at the end of telophase I, you have one homologue in each cell...that homologue then goes through meiosis II, and at metaphase II, that homologue lines up at the metaphase plate with each sister chromatid facing each pole, and the chromosome is "pulled apart".  Anaphase II pulls the sister chromatids to each pole, and cytokinesis splits the one cell into two....two cells, each containing one sister chromatid of a homologous pair. (although in some text books this is refered to as a single homologue)