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Prophase: The two round objects above the nucleus are the centrosomes. The chromatin has condensed.
: Main article: Prophase Normally, the genetic material in the nucleus is in a loosely bundled coil called chromatin. At the onset of prophase, chromatin condenses together into a highly ordered structure called a chromosome. Since the genetic material has already been duplicated earlier in S phase, the replicated chromosomes have two sister chromatids, bound together at the centromere by the cohesion complex. Chromosomes are visible at high magnification through a light microscope. Close to the nucleus are structures called centrosomes, which are made of a pair of centriole. The centrosome is the coordinating center for the cell's microtubules. A cell inherits a single centrosome at cell division, which replicates before a new mitosis begins, giving a pair of centrosomes. The two centrosomes nucleate microtubules (which may be thought of as cellular ropes or poles) to form the spindle by polymerizing soluble tubulin. Molecular motor proteins then push the centrosomes along these microtubules to opposite side of the cell. Although centrosomes help organize microtubule assembly, they are not essential for the formation of the spindle, since they are absent from plants,[8] and centrosomes are not always used in meiosis.[10]
What else can I help you with?
How is prophase1 different in meiosis than in mitosis?
on prophase of mitosis the cylindrical shaped structure(centrioles) starts to move going to the both opposites sides as they move the fiber make-up structure starts to form(spindle). The spindles is the one who controls the movement of the choromosomes while it is in the process. note the chromosomes starts to become shorten ad thick that's why they r very easy to see. in prophase I of meiosis the choromoses condense and are seen to have splitinto two chromatids. One of its important features of the phrophase I of meiosis the paternal and maternal chromosomes come together in homologous pairs., well that's my answer i know its ryt... hope that i have helped you. -joan- The answer by joan simply states the processes that occur individually by mitosis and meiosis. The question is to discuss the 'Difference' instead of state the events that occur. In my understanding, prophase 1 of meiosis consists of 5 different stages - Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis. Now the question is which of these 5 stages differ from prophase of mitosis. I found that stages Leptotene (condensation of DNA) and Diakinesis (nuclear envelop fragments) are similar to that in prophase of mitosis. Thus, the difference has to lie in stages Zygotene (formation of bivalents and synaptonemal complex), Pachytene (crossing over at sites called chiasma) and Diplotene (separation of synaptonemal complex). Do improve on my answer. glenn
What is the significance of meiosis in the formation of haploid gametes and its role in genetic variability?
Here are a few points of that broad question:The process of meiosis creates haploid cells (containing a single chromosome set). It introduces a large amount of variablitilty in offspring through the following:Independant Assortment:During Metaphase I the homologous pairs (consisting of one maternal and one paternal chromosome) are situated at the metaphase plate. Each pair may orient its maternal or paternal homolog closer to either pole. Each of the pairs are positioned independantly, each side have a 50% chance of receiving either maternal or paternal chromosomes.The number of combinations that are possible for daughter cells formed by a diploid cell is 2n (n is the haploid number of an organism, for humans the haploid number is 23)Crossing Over:During Phrophase I homologous chromosomes pair loosely along their lengths and the exchange of two corresponding segments of two nonsister chromatids (one paternal and one maternal) occurs.Different arrangements of nonidentical sister chromatids druing meiosis II increase variability.*Products of meiosis allows for random fertilization*The fusion of a male gamete with a female gamete during fertilization will produce a zygote with any of about 70 TRILLION (223 X 223) diploid combinations.Neil A.Campbell, Jane B. Reece, Biology 8th edition, 2008. Pgs 254-259
Chromatin is found in what phase of the cell cycle?
Chromatin is found during the interphase of the cell cycle, which is divided into three stages: G1, S, and G2. Chromatin is the complex of DNA and proteins that makes up the chromosomes in a non-condensed form during interphase.
How many times does DNA replicate in meiosis?
1 time only which is done during the only interphase in meiosis.
What phase of mitosis do the cells contain one single strand of DNA?
Anaphase is the stage of mitosis wherein chromosomes are split and the sister chromatids move to the opposite poles of the cell. This stage accounts for approximately 1 percent of the cell cycle's duration.
What is swapping of genetic material between homologous chromosomes?
Swapping of genetic genetic material is when two chromosomes (maternal and paternal) with the same gene sequence exchange genes, this occurs during Phrophase 1 of meiosis by a process called crossing over. Hope this helps.
What are the major events in each of the phases of mitosis?
I like to think of this as a word game, here to help you. Interesting {Interphase} Purple {Phrophase} Monkeys {Metaphase} Ate {Anaphase} Tangerines {Telophase} Constantly! {Cytokinses} Now that we have this established, here is what happens. During INTERPHASE,- The cell grows, and DNA is coppied. During PHROPHASE,- The Chromosomes {DNA} become more and more visible {and from stringy to rod{like}. The centrioles move from opposite sides, spindle fibers form, and the Nuclear envolope dissapears. During METAPHASE,- Chromosomes line up in middle of the cell, and spindle fibers attach to chromosomes. {Center Centromere} During ANAPHASE,- Chromosomes split at the centromere, chromosomes pulled to the oppsite sides of a cell by spindle fibers, and cell streches out. During TELOPHASE- Chromosomes start to loose rod-like and become stringy, Nuclear envelopes form aroud chromosomes. Spindle dissolves. And Lastley....... During CYTOKINESIS- Cell membrane pinches around the middle of the cell {almost forming a kidney bean},and Cell splits into two identical daughter cells! ......{Then repeat to Interphase....}D Hope this helped! :D
What are the parts of the cells?
Cell wall (ONLY IN PLANT CELLS) Cell Membrane Nucleus Cytoplasm Chloroplast (ONLY IN PLANT CELLS) Mitochondrion (ONLY IN ANIMAL CELLS) Vacuole Ribosomes Lisosomes Endoplasmic Reticulum Golgi Bodies
How is prophase1 different in meiosis than in mitosis?
on prophase of mitosis the cylindrical shaped structure(centrioles) starts to move going to the both opposites sides as they move the fiber make-up structure starts to form(spindle). The spindles is the one who controls the movement of the choromosomes while it is in the process. note the chromosomes starts to become shorten ad thick that's why they r very easy to see. in prophase I of meiosis the choromoses condense and are seen to have splitinto two chromatids. One of its important features of the phrophase I of meiosis the paternal and maternal chromosomes come together in homologous pairs., well that's my answer i know its ryt... hope that i have helped you. -joan- The answer by joan simply states the processes that occur individually by mitosis and meiosis. The question is to discuss the 'Difference' instead of state the events that occur. In my understanding, prophase 1 of meiosis consists of 5 different stages - Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis. Now the question is which of these 5 stages differ from prophase of mitosis. I found that stages Leptotene (condensation of DNA) and Diakinesis (nuclear envelop fragments) are similar to that in prophase of mitosis. Thus, the difference has to lie in stages Zygotene (formation of bivalents and synaptonemal complex), Pachytene (crossing over at sites called chiasma) and Diplotene (separation of synaptonemal complex). Do improve on my answer. glenn
What is the significance of meiosis in the formation of haploid gametes and its role in genetic variability?
Here are a few points of that broad question:The process of meiosis creates haploid cells (containing a single chromosome set). It introduces a large amount of variablitilty in offspring through the following:Independant Assortment:During Metaphase I the homologous pairs (consisting of one maternal and one paternal chromosome) are situated at the metaphase plate. Each pair may orient its maternal or paternal homolog closer to either pole. Each of the pairs are positioned independantly, each side have a 50% chance of receiving either maternal or paternal chromosomes.The number of combinations that are possible for daughter cells formed by a diploid cell is 2n (n is the haploid number of an organism, for humans the haploid number is 23)Crossing Over:During Phrophase I homologous chromosomes pair loosely along their lengths and the exchange of two corresponding segments of two nonsister chromatids (one paternal and one maternal) occurs.Different arrangements of nonidentical sister chromatids druing meiosis II increase variability.*Products of meiosis allows for random fertilization*The fusion of a male gamete with a female gamete during fertilization will produce a zygote with any of about 70 TRILLION (223 X 223) diploid combinations.Neil A.Campbell, Jane B. Reece, Biology 8th edition, 2008. Pgs 254-259
