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DeKalb County - Purdue University
DeKalb County - Purdue University

... h. It is the chromosome from which parent that determines the sex of the kit: ___________ 6. List the correct term for each definition: minute rod-like structures on which genes are located. It is one single molecule of DNA genes that suppress other genes with the same characteristics. This gene wil ...
Chapter 15 Study Questions
Chapter 15 Study Questions

... *condensed, inactive “X” (sex) chromosome (most genes are not expressed); condenses during embryonic development How many Barr bodies are there in each female somatic cell? ...
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7.1 Chromosomes and Phenotype
7.1 Chromosomes and Phenotype

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R 7.1
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... • Autosomal genes: There are two copies of each autosome, which means that there are two copies of each autosomal gene. However, the two copies of a gene may be different alleles. Both copies of a gene can affect phenotype. Much of what has been learned about human genes comes from studies of geneti ...
An Aside: X Inactivation in Female Mammals
An Aside: X Inactivation in Female Mammals

... If an entire organism has more than two complete chromosome sets it is POLYPLOID (triploid=3n, tetraploid=4n, etc.) Red viscacha rat from Argentina = 4n ...
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6.5 , 7.1

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Linked Genes - Deepwater.org
Linked Genes - Deepwater.org

... A male XhY or a female XhXh* would express the trait. * This is not always true for females, due to X-inactivation. A male could receive the trait from a mother that does not express the trait. But for a female to receive the trait, her father would have to be a hemophiliac. This is why sex-linked t ...
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... A. In humans XX is female and XY is male 1. The SRY gene has been shown to trigger the development into a male fetus at about 2 months old. 2. SRY probably regulates other genes 3. Some XX male and XY females exist with mutated SRY genes ...
Chapter 15: The Chromosomal Basis of Inheritance
Chapter 15: The Chromosomal Basis of Inheritance

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Chapter 10 PowerPoint - Bryn Mawr School Faculty Web Pages
Chapter 10 PowerPoint - Bryn Mawr School Faculty Web Pages

... meiosis, the genes that they contain are also independently assorted only if they are part of different chromosomes. Genes in the same chromosome are passed on together as a unit. Such genes are said to be linked. For example, the "A" and "B" alleles (in the illustration below) will both be passed o ...
Variation - Intermediate School Biology
Variation - Intermediate School Biology

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Beyond Dominant & Recessive Alleles

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BioSc 231 2001 Exam4
BioSc 231 2001 Exam4

... _____ A female Drosophila supposedly heterozygous for two recessive mutations cn and lz that are on the same arm of the X chromosome (cn lz/+ +) surprisingly expresses both these genes. The male progeny of the female will be A. all wild type B. all cn lz C. 1/2 cn lz and 1/2 wild type D. cn + E. + l ...
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Human Genes

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Autosomal & Chromosomal Disorders
Autosomal & Chromosomal Disorders

...  Most cases of DS are trisomy 21, however there are other types of DS (Mosaic and Translocation) .  Often DS is associated with some impairment of cognitive ability and physical growth as well as facial appearance.  The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, althoug ...
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Meiosis 1. What would happen if the chromosomes didn`t line up on

... In  the  end,  the  two  daughter  cells  would  have  uneven  amounts  of  chromosomes.  For  example,   one  cell  would  have  too  many  and  the  other  would  not  have  enough   2.   What  is  this  case  called?   Aneuploidy ...
TURNER SYNDROME - Aristotle University of Thessaloniki
TURNER SYNDROME - Aristotle University of Thessaloniki

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Mutation - World of Teaching
Mutation - World of Teaching

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Notes on Chromosomal Mutations

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Autosomal & Chromosomal Disorders

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Document
Document

... Males are hemizygous for X chromosome gene expression, and a mutation of MeCP2 will lead to a loss or partial inactivation of the MeCP2 function. The severe phenotype in males results in early lethality. Theory 2 for female bias: Theory 1 does not explain why there are some males with Rett syndrome, ...
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Skewed X-inactivation

Skewed X chromosome inactivation occurs when the inactivation of one X chromosome is favored over the other, leading to an uneven number of cells with each chromosome inactivated. It is usually defined as one allele being found on the active X chromosome in over 75% of cells, and extreme skewing is when over 90% of cells have inactivated the same X chromosome. It can be caused by primary nonrandom inactivation, either by chance due to a small cell pool or directed by genes, or caused by secondary nonrandom inactivation, which occurs by selection. Most females will have some levels of skewing. It is relatively common in adult females; around 35% of women have skewed ratio over 70:30, and 7% of women have an extreme skewed ratio of over 90:10. This is of medical significance due to the potential for the expression of disease genes present on the X chromosome that are normally not expressed due to random X inactivation. X chromosome inactivation occurs in females to provide dosage compensation between the sexes. If females kept both X chromosomes active they would have twice the number of active X genes than males, who only have one copy of the X chromosome. At approximately the time of implantation (see Implantation (human embryo), one of the two X chromosomes is randomly selected for inactivation. The cell undergoes transcriptional and epigenetic changes to ensure this inactivation is permanent. All progeny from these initial cells will maintain the inactivation of the same chromosome, resulting in a mosaic pattern of cells in females.
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