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Chapter 13 – Meiosis and Sexual Life Cycles
Chapter 13 – Meiosis and Sexual Life Cycles

... During prophase I of meiosis, replicated homologous chromosomes line up and become physically connected along their lengths by a zipperlike protein complex, the synaptonemal complex, in a process called synapsis. Genetic rearrangement between nonsister chromatids called crossing over also occurs. On ...
Slide 1 - Faculty Web Pages
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... 2.) Determine genotypes for heterozygous parent and cross-progeny, based on the phenotypes. You should already know the genotype of the homozygous parent Do the genotypes give chromosome information? 3.) Write down chromosome from homozygous test-cross parent that crossprogeny inherited. Now you are ...
The Meaning of Sex: Genes and Gender
The Meaning of Sex: Genes and Gender

... 21. Student question: Can a nematode get Down syndrome? 22. Student question: How can Turner syndrome have effects if X inactivation occurs? 23. Student question: What happens in XXX nematodes? 24. Student question: What actually kills when there is no dosage compensation? 25. Student question: How ...
hered master 4..hered 285 .. Page78
hered master 4..hered 285 .. Page78

... Genotype 193 had 21 chromosomes of which eight belonged to the Lm genome, seven to Fp and six to Fg/Fg1 (Fig. 1a). Genotype 219 also had 21 chromosomes: seven Lm, six Fp and eight Fg/Fg1 (Fig. 1b). Recombinants involving all three genomes were observed (an example of each combination is illustrated ...
CHAPTER 13 MEIOSIS AND SEXUAL LIFE CYCLES
CHAPTER 13 MEIOSIS AND SEXUAL LIFE CYCLES

... During prophase I of meiosis, replicated homologous chromosomes line up and become physically connected along their lengths by a zipperlike protein complex, the synaptonemal complex, in a process called synapsis. Genetic rearrangement between nonsister chromatids called crossing over also occurs. On ...
Low chromosome number angiosperms
Low chromosome number angiosperms

... quences suggesting that B chromosomes did not arise directly from one of the A complement chromosomes. By fluorescence in situ hybridization Donald et al. (1995) revealed the presence of an rRNA gene cluster on both the A and B chromosomes of B. dichromosomatica. An highly methylated tandem repeats ...
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... peer-reviewed) is the author/funder. It is made available under a CC-BY-NC-ND 4.0 International license. ...
Remarkably Little Variation in Proteins Encoded
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... may be due to higher variance in reproductive success among men than among women,8 which would further reduce the effective population size of Y chromosomes. The results reported here shed new light on an important question: how representative or typical is the sequenced human Y chromosome? Previou ...
Bewildering Bs: an impression of the 1st B-Chromosome
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... Another intriguing point that was raised is why are there so few organisms with many different types of Bs? This does not seem to result solely from a lack of study. From a selective point of view, it may be that there is a narrow niche for a B to exist in a species and hence strong selection for a ...
1. Interpreting rich epigenomic datasets
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genetic control of pigment differentiation in somatic cells
genetic control of pigment differentiation in somatic cells

... but often the powerful tool of genetic analysis is left unused. One facet of this problem which might be particularly susceptible to analysis by use of genetic techniques is implicit in the title of this paper: the genetic control of pigment differentiation. By the term "genetic control" it is meant ...
Genome-Wide Gene Expression Effects of Sex Chromosome
Genome-Wide Gene Expression Effects of Sex Chromosome

... and histone modifications established during oogenesis and spermatogenesis (Sha 2008). In mammals, gynogenetic offspring are inviable (McGrath and Solter 1984; Thomson and Solter 1988), indicating that a balanced contribution of chromosomes of paternal and maternal origin is required for development ...
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... by the function of the Ph1 gene (Riley and Chapman 1958), located on chromosome 5B(5BL), and the Ph2 gene on chromosome 3DS and 3AS (Mello-Sampayo 1971). The Chinese Spring ph1b (CSph1b) mutant genotype (Sears 1977), which lacks the Ph1 locus, has been successfully used for the introgression of alie ...
Gender in plants: sex chromosomes are emerging from the fog
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... Although most plants have flowers with both male and female sex organs, there are several thousands of plant species where male or female flowers form on different individuals. Surprisingly, the presence of well-established sex chromosomes in these dioecious plants is rare. The best-described exampl ...
Slide 1
Slide 1

... - Gene Pool: sum total of alleles held by individuals in a population - Genetic structure: Gene array and Genotypic array - Gene/Allele Frequency: % of alleles at a locus of a particular type - Gene Array: % of all alleles at a locus: must sum to 1. - Genotypic Frequency: % of individuals with a par ...
Why haplotype analysis is not critical in genome wide association studies Derek Gordon
Why haplotype analysis is not critical in genome wide association studies Derek Gordon

... Example – Alzheimer’s Disease One of the most well-documented and replicated results of a risk locus for late onset Alzheimer’s Disease (AD) is the APOE gene on Chromosome 19. There are three alleles at this locus, labeled ε2, ε3, and ε4. The last (ε4) is the risk allele for the AD. ...
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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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