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10 Cards in this Set
- Front
- Back
Maternal Effect |
The phenotype of the offspring depends solely on the GENOTYPE of the mother. Nurse cells provide egg with nutrients and other materials, and gene products are transferred in this process. If mother is Dd or DD, offspring phenotype is always D regardless of male genotype |
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Dosage Compensation |
The equalization of gene expression between the males and females of a species. Because sex chromosomes contain different numbers of genes, different species of organisms have developed different mechanisms to cope with this inequality. Replicating the actual gene is impossible; thus organisms instead equalize theexpression from each gene. In humans, the females (XX) silence the transcription of one X chromosome of each pair, and transcribe all information from the other, expressed X chromosome. Thus, human females have the same number of expressed X-linked genes as do human males (XY), both genders having essentially one X chromosome per cell, from which to transcribe and express genes. |
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X Inactivation |
X chromosome is inactivated through a compaction mechanism involving DNA methylation Occurs at random Ex. Calico cat |
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Lyon Hypothesis |
Dosage compensation in mammals is by inactivation of all but one X chromosome in cells with more than one X chromosome. The Barr body, visible in some female mammalian cells, is an inactivated X chromosome. |
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Snail coiling at the cellular level |
D gene products cause egg cleavage that promotes a right handed body plane and d gene products do the opposite |
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X-inactive specific transcript |
Expressed on inactive X chromosome |
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X-chromosomal controlling element |
Affects choice of X chromosome to be activated |
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Xist RNA |
coats chromosome and transforms it into a Barr body |
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Genomic imprinting |
A segment of DNA is marked, and that mark is retained and recognized throughout the life of the organism inheriting the marked DNA |
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Angelman syndrome |
Does not carry active copy of the AS gene, which is necessary for protein degradation. |