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Saturday, April 6, 2013

Uniparental Disomy and Karotypes

Day 29: Uniparental Disomy

On our 29th day of MARCHING into TRISOMY AWARENESS we are going to share a little bit about UNIPARENTAL DISOMY. Uniparental disomy (UPD) occurs when a person receives two copies of a chromosome, or of part of a chromosome, from one parent and no copies from the other parent. UPD can be the result of heterodisomy, in which a pair of non-identical chromosomes are inherited from one parent or isodisomy, in which a single chromosome from one parent is duplicated. Because it may lead to the duplication of lethal recessive genes, isodisomy is potentially dangerous, while heterodisomy is essentially benign. This can also be the result of a TRISOMY CELL RESCUE (also known as trisomy rescue or trisomy zygote rescue) a genetic phenomenon in which a fertilized ovum containing three copies of a chromosome loses one of these chromosomes to form a normal, diploid chromosome complement. If both of the retained chromosomes came from the same parent, then uniparental disomy results. Share because you care...we did ♥

Day 30: Karotypes

On our 30th day of MARCHING into TRISOMY AWARENESS we are going to share a little bit about KAROTYPES A karyotype (Greek karyon = kernel, seed or nucleus) is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism. Karyotypes describe the number of chromosomes, and what they look like under a light microscope. Attention is paid to their length, the position of the centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics.The preparation and study of karyotypes is part of cytogenetics. The study of whole sets of chromosomes is sometimes known as karyology. The chromosomes are depicted (by rearranging a microphotograph) in a standard format known as a karyogram or idiogram: in pairs, ordered by size and position of centromere for chromosomes of the same size.The study of karyotypes is important for cell biology and genetics, and the results may be used in evolutionary biology and medicine. Karyotypes can be used for many purposes; such as to study chromosomal aberrations, cellular function, taxonomic relationships, and to gather information about past evolutionary events. The normal human karyotypes contain 22 pairs of autosomal chromosomes and one pair of sex chromosomes. Normal karyotypes for females contain two X chromosomes and are denoted 46,XX; males have both an X and a Y chromosome denoted 46,XY. Any variation from the standard karyotype may lead to developmental abnormalities. Share because you care...WE DID ♥

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