what is balanced robertsonian translocation ?
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A Robertsonian translocation in balanced form results in no excess or deficit of genetic material and causes no health difficulties. In unbalanced forms, Robertsonian translocations cause chromosomal deletions or addition and result in syndromes of multiple malformations, including trisomy 13 (Patau syndrome) and trisomy 21 (Down syndrome).
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Here is a good treatment on it:\n\nhttp://qhr.sagepub.com/cgi/reprint/13/7/893.pdf
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A look at http://en.wikipedia.org/wiki/Transmutation\nshould answer your ?
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I believe you are asking about a transposition? They are related because a transposition is when the order of alleles a chromosome gets changed around during meiosis and mitosis, possibly causing a mutation. This type mutation can be caused by sister cromatids not being able to find a match because of the transposition.
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Transformation\nNucleotides\nBase
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In prophase 1 the DNA condensates, attaches to the nuclear envelope and crossing over occurs (not necessarily).  Then the chromosomes migrate into metaphase positioning.\n\nIn metaphase 1 the DNA tetrads align and get ready to segregate.\n\nThat's the big difference.\n\nCheers.
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click here:http://rds.yahoo.com/_ylt=A0geus1fYEtFnSMBRr1XNyoA;_ylu=X3oDMTE2ZGhvZmh2BGNvbG8DZQRsA1dTMQRwb3MDMQRzZWMDc3IEdnRpZANERlg1XzMw/SIG=12otu01pa/EXP=1162654175/**http%3a//www.chm.bris.ac.uk/webprojects2001/loveridge/index-page8.html
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I can't speak for people who hold the creationist world view, but as far as biology is concerned, the change you are thinking of is probably the "change in allele frequency over time." This change is called Evolution. \n\nStrictly speaking though, division is change, and so is movement. Just not a change in the ability of the cell to undergo its functions. Just like my computer would be the same computer if I moved it to a different room. If I changed the code on the computer though, I would consider that a change.
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They share just about everything - size, morphology (metacentric, submetacentric or acrocentric) and banding pattern at metaphase (see http://members.aol.com/chrominfo/geninfo.htm for a nice quick explanation of these things).\n\nWhat will not be shared will be minute variations in the exact sequence of the DNA, given that half of the sequence will orginate from the mother and half from the father. These genetic differences account for phenotypic (physical) differences following expression of all the genes and contribute to the fact that your parents are not identical.
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the ploidy no is 2n\nbut the dna amount is double. it changes in the metaphase or late prophase
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A. You have co-dominance in a heterozygous match, so the off spring ratio would not be the normal heterozygous, but would come out as a homozygous cross.\n\nB. Call your recessive allele, a. If you did the cross with a non-recessive you would have 1/4 homozygous,aa, progeny. Lethals, when homozygous, will die. You can see that messes with the Mendelian ratio.
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There is no crossing over during prophase 2! It's a fact. That answers your question pretty nicely.
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From your question, I kind of get the impression that you or someone you know is carrying a fetus with the chromosomal abnormality you mentioned.  In that case, the doctor who diagnosed the condition should also have discussed the implications of the abnormality with the child's parents.  If you're asking because this is something you're having to deal with, you doctor or genetic counselor should be able to provide far more information than I can.\n\nPresumably the fetus is missing the long arm of only one copy of chromosome 20.  Were both copies effected, the fetus would likely self-abort in the early stages of the pregancy.  Missing a copy of a chromosome is known as monosomy, and is generally followed by a number indicating which chromosome is effected.  When only part of one copy of the chromosome is missing, it's called a partial monosome.  So a child missing part of chromosome 20 is said to have partial monosomy 20.\n\nThere seems to be very little information available about how partial monosomy 20 would effect a child.  It is quite possible that the child would either self-abort (i.e. miscarry) in the early stages of fetal development, or would be still-born.  If the child were born live, he or she would probably have pronounced physiological and developmental abnormalities.  \n\nChildren with many different chromosomal abnormalities are likely to have mental retardation (and potentially other psycological and behavioral difficulties), deformities of internal organs (ex. heart defects), and a markedly abnormal physical apearance.  But they can still be happy, loving children, and grow to become productive members of society.
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http://www.webmd.com/hw/raising_a_family/tp22217.asp\nhttp://www.orthoseek.com/articles/congenmt.html\ngo to this website
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Any process resulting in the breakage of chromosomes or the loss or rearrangement of pieces of chromosomes
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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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Nondisjunction.  \n\nNondisjunction occurs when homologous chromosomes fail to separate during meiosis.  This results in two cell with two copies of the chromosome (when it should one have one) and two cells with none (remember that meoisis produces four haploid cells).  If the cell with the extra copy fertilizes/is fertilized by a normal haploid gamete, the result will be a trisomy.  If a cell that's missing its copy of the chromosome combines with a normal haploid cell, there result is monosomy.\n\nThe other three choices (inversion, translocation, and crossing-over) involve changes in sequence, rather than chromosome structure or number.