Human Chromosomal Disorders© Copyright NewPath Learning. All Rights Reserved. 94-4773Visit www.newpathlearning.com for Online Learning Resources.Chromosomal errors that occur during meiosis can lead to mutations in sex cells. If an error occurs in an egg or sperm, the person made from that cell will have the change in every cell of their body.Errors During SegregationErrors can occur when chromosomes segregate into the sex cells during meiosis resulting in egg or sperm with too many or too few chromosomes. As a result, fertilized eggs and the resulting embryos may have trisomy (an extra chromosome of a particular pair) in each cell or monosomy (one chromosome fewer in each cell). Genetic disorders that result from too many or too few chromosomes include: Errors During RecombinationOther errors in chromosomes that can occur during meiosis include duplication (extra genetic material), deletion (missing genetic material) and translocation (part of one chromosome becomes attached to another). The severity of the effects of these disorders depends on the size of the chromosome fragment involved and the genetic information contained in it.Turner syndrome is caused by a missing or incomplete X chromosome. People who have Turner syndrome develop as females. Because some of the genes on the X chromosome are involved in growth and sexual development females with this disorder are shorter than normal and have incompletely developed sexual characteristics.Down syndrome, also called “trisomy 21,” is a developmental disorder caused by an extra copy of chromosome 21. The extra chromosome causes problems with the way the body and brain develop.47, XXY (or XXY) is a genetic condition that primarily affects sexual development caused when someone has two X chromosomes and one Y chromosome. Males normally have one X chromosome and one Y chromosome (46, XY), and females normally have two X chromosomes (46, XX). 12367891011121314192021221516171845XXY extra XchromosomeKlinefelterSyndrome - Trisomy12367891011121314192021221516171845X (female)loss of 2nd XchromosomeTurnerSyndrome - MonosomyXX (female) XY (male)or12367891011121314192021221516171845DownSyndrome - Trisomy 21extra chromosomeduplicated genetic materialdeleted genetranslocatedgenetic materialABChromosomal errors that occur during meiosis can lead to mutations in sex cells. If an errrrooooooooorrrrrr occcccccccccccccccuuuuuuuuuuurrrrrrrrrrrrssssss iiiiiiinnnnnnnnnnn aaaaaaaaaaaannnnnnnnnnnnn egg or speeeeeeeeeeeerrrrrrrrrrrrmmmmmmmmmmmmmmmmmmmm,,,,,,,,, tttttttttttttthhhheeeeeeeeeeee person made from that cell will have the change in every cell of their body.Errors can occur when chromosomes segregate into the sex cells during meiosis ressssssssuuuuuuuuuuuuuuullllllllllllltttttttttttiiiiiiiiiiiing in eeeeeeeeeeegggggggggggggggggggggggggg ooorrrrrrrrrrr ssssssssssppppppppppppppppeeeerm wwwwwwwwwwwwiiiiiiiiiitttttttttthhhhhhhhh toooooo mmmmmmmmmmmmmmmmmaaaaaaaannnnnnnnnnnnnnyyyyyyyyyyyyy ooor too few chromosomes. As a result, fertilized eggs and the resulting embryos may have trisomy (((((((((((aaaaaaannnnnnnnnnnnn eeeeeeeeeexxxxxxxxxxxxtttttra cchhhhhhhhhhhhhhhhhrrrrrrrrrrroooooooooooommmmmmmmmmmmoooooooooooooosssssssssssooooooooooome of a particular pair) in each cell or monosomy (one chromosome fewer in each cell). Genetic disorders that result from too many or too fewchromosomes include:Other errorrrrrrrrrrrrsssssssssssss innnnnnnn cccccccccchhhhhhhhhhhhhhhhrrrrrrrrrroooooooooooooommmmmmmmmmmmmooooooooooosomeeeeeeeeeesssssssssss ttttttttttthhhhhhhhatttttttttt cccccccccccaaaaaaaaaaaannnnnnnn occuuuuuuuuuuuurrrrrrrrrrr ddddddddddddduriiiiiiinnnnnnnnnnnnggggggggggggggggg mmmmeiosis include duplicatiiiiiiiooooooooooooooon (((((((((((eeeeeeeeeeeeeeeeexxxxxxxxxxxxxtttttttttttttttrrrrrrrrrrraaaaaaa gggggggggggggggeeeeeeeeeeneeeeeeeeeeetttttttttttiic materrrrrrrriiiiiiiiiiiaaaaaaaaaaaaalllllllll)))))))))),,,,,,,, dddddddddddeeeeeeeeeellllllllllleeeeeeeeeettttttion (((((((((((mmmmmmmmmmmmmmmiiiiiiiiissssssssssssinnnngggggggggggggggggg genetic material) and trannnnnnnnnnnnnssssssssslooccccccccccccccaaaaaaaaaaaaaaatttttttttttttttttttiiiiiiiiiiiiiiooooooooooooooonnnnnnnnnnnnnnnn ((((((((((pppppppppppppaaaaaaaaaarrrrrrrrrtttttt oooooofffffffffffff ooooooooooooonnnnnnnnnnnnnnne chrommmmmmmmmmmmmmoooooooooooooosssssssssssooooooommmmmmmmmmeeeeeeeeeee bbbbbbbbbbbbeecoooooommmmmmmmmmmmmmmes aaaaaaaaaatttttttttttached to anothhheeeeeeeeeeeeeerrrrrrrrrrrr))). TTTTTTTTTTTTThhhhhhhhhhhhhhhhhheeeeeeeeeeeeeee ssssssssssssssseeeeeeeeeeeeeevvvvvvvvvveeeeeeeeeeeeerrrrrrrrriiiiiiiiitttttttttyyyyyyyyyyyyyy oooooooooooooooffffffffffffff tttttttttttthhhhhhhhhhe eeeeeeeeeeefffffffffffffffffffffffffffffeeeeeeeeeeeeeeccccccccccts of thhhhhhhhhhhheeeeeeeeeeeesssssssssssseeeeeeeeeeee dddddddiiiiiiiiissssssssssssooooooooooorrrrrrrrrdddersssssssssssss dddddddddepends on the size of thhhhhhhhhhheeeeeeeeeeeeee chhhhhhhhhrrrrrrrrrrroooooommmmmmmmmmmmmmmmmmmooooooooooooooooossssssssssssoooooooooommmmmmmmmmmmmmeeeeeeeeeee fffffffffragmeennnnnnnnnntttttttttttt iiiiiiiiiiiinnnnnnnnnnnnvooooooooollllllllllvvvvvvvvvvvvveeeeeeeeeeeeeedddddd and tttttttthhhhhhhhhhhhhheeeeeeeeeee ggggggggggggggeneeeeeeeeeeeeetttttttttttttiiiiiiic information contained in it.Turner syndrome is caused by a missing or inccccooooooooooommmmmmmmmmmmmmpppppppppppllllllllllllleeeeeeeeetttttttttttteeeeeeeeeee XXXXXXXXXXXXX chromosome. People who have Turner syndrommmmmmmmeeeeeeeeeee ddddddddddddeeeeeeeeeeeevvvvvvvvvvvvvveeeeeeeeeeeeelllllllllllooooooooooopppppppppppp as females. Because some of the genes on thhhhhhheeeeeeeeeeeeee XXXXXXXXXXXXXXXX cccccchromosome are involved in growth and sexual developpppppppppppppppmmmmmmmmmmmmmmmeeeeeeeeeeeeeeennnnnnnnnnnnnnnt femmmmmmmmmmmmmmmmaaaaaaaaaaalllllllllllleeeeees with this disorder are shorter than normal andddddddddddd hhhhhhhhhhhhhhhaaaaaaaaaaaavvvvvvvvvvvvvve innnnnccccccccccooooooooooooooommmmmmmmmmmmmmmmppppppppleteeeeeeeeeeeellllllllyyyyyyyyyyyyy developed sexual characteristics.Down syndrome, alsooooooooo cccccccccccaaaaaaaaaaaaaaalllllllllllllllledddddddd ““““““ttttttttttttttttrrrrrrrrrrriiiiiiiiiissssssssomy 21,” is a developpppppmmmmmmmmmmmmmmmmmmmeeeeeeeeeeeeennnnnnnnntttttaaaaaaaaaalllllllllllll disorder caused byyyyyyy an extrrraaaaaaaaaaaaa ccccccccccooooooooooooopppppppppppppy ooooooooooooffffffffffff ccccccccccccccchhhhhhhhhhhromosome 21. The exxxxxxtttttttttttrrrrrrrrrrrraaaaaaaaaaa chromosome caaaaaaaaaaaauuuuuuuuuuusess ppppppppppppppppprrrrrrrrrroooooooblems wwwwwwwwwwwwiiiiiiiiiiiiitttttttttttthhhhhhhhhhhhhhh thhhhheeeee wwwwwwwwwwwwwwwaaaaaaaaaaaayyyyyyy the body and brrrrrrrrrrrraaain develop.47, XXY (or XXY) is a genetic condition that primarily affffffffffffeeeeeeeeeeeeeeectssssssssssssss sexual development caused when someone has two X chromosomes and one Y chromosome. Males normally hhhhhhhhhaaaaaaaaaavvvvvvvvvvvvveeeeeeeeeeeeeee one X chromosome and one Y chromosome (46, XY), and females normally have two X chromosomes (46, XX). 12333367898898989899899989881011123331313131131313133314192021212112121222121221151551555551511116171844544444XXY extraXchromosomeKKKKKKKKKKKKKKlllllllllllineeeeeffffffffffffeeeeeeeeeeellllllllttttttttttteeeeeeeeeeeerrrrrrrrSynddddddddddddddddrrrrrrrrroooooooommmmmmmmmmeeeeeeeeeeee - Trisooommmmmmmmmmmmmyyyyyyyyyyyyy121222221212212123776676777767777778910111213131313313133314111191112021221516171845X (female)ffloss of 2ndXchromosomeTurnerSyndrome - MonosomyXX (female)ffXY (male)or12367891011121314192021221516171845DownSyndrome - Trisomy 21extra chromosomeduplicated ggenetic materialdeleted genetranslocatedgenetic materialAB
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