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LP - Columbia University
LP - Columbia University

... B. What do you see in a normal squash or karyotype? (Any of the topics below that are not covered in this lecture will be discussed next time.) 1. Can see number of chromosomes, size and shape (determined by position of centromere) for each chromosome and can identify each individual chromosome by b ...
Chapter 10 Meiosis
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... – Nonsister chromatids exchange segments in a process called crossing over – Because alleles for the same trait can vary, new combinations of genes in each chromosome can result; this is one source of genetic variation – After crossing over, the nonsister chromaids begin to partially separate but re ...
Sex-chromosome evolution: recent progress and the
Sex-chromosome evolution: recent progress and the

... there are recently evolved sex chromosomes (neo-sex chromosomes) formed by fusions or translocations involving autosomes, giving systems such as Z 1Z2W/ Z1Z1Z2Z2 and XY1Y2/XX, to name just two examples. Some plants, invertebrates and, as recently discovered, the platypus and echidnas (the monotreme ...
Slide 1
Slide 1

... Abnormal numbers of sex chromosomes do not usually affect survival  The following table lists the most common human sex chromosome abnormalities. In general, – a single Y chromosome is enough to produce “maleness,” even in combination with several X chromosomes, and – the absence of a Y chromosome ...
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... Law of Independent Assortment: Alleles of different genes separate independently during gamete formation. Therefore, traits pass to offspring independently of each other. – = The parent makes an equal number of each of the four kind of gametes. A gamete with an allele from one gene does not force it ...
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CHAPTER 10

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The information in this document is meant to cover topic 4 and topic
The information in this document is meant to cover topic 4 and topic

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Mendel's genetics - Klahowya Secondary School
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... Homozygous means having the same alleles (e.g. bb), while heterozygous means having different alleles (e.g. Bb). A genotype is the person’s genetic makeup, for example if they had blue eyes, their genotype would be bb. A phonotype is how this is actually seen as a characteristic, or which alleles ar ...
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Sex-Linked/Codominant/Incomplete Dominant Quiz
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... Do not write on this quiz! Only fill out your answer sheet. Writing on this quiz will result in a loss of 5% on your final score. 1. What is the difference between genotype and phenotype? a. Genotype is the physical characteristics; phenotype is the genetic make-up. b. Genotype is the genetic make-u ...
Red Biology guide 235
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... (A warm-up, so skip this one if you are used to showing X and Y segregation using demonstration chromosomes, and determining probabilities of segregation outcomes.) A person with this condition is XY. The recessive mutation that causes AIS is on the X chromosome. Show all the relevant chromosomes pa ...
TechniquesPresentationQuestion
TechniquesPresentationQuestion

... Thus, relative cross-linking frequencies will be monotone decreasing as fragments become farther apart on the chromosome, which is roughly what we see in the fetal brain cells, especially when compared to the fetal liver cells. 3) This statement is true because the relative cross-linking frequencies ...
Examples of connected symbols:
Examples of connected symbols:

... than the X chromosome and appears to contain only a few genes. ...
Heredity
Heredity

... A sex-linked trait is a trait whose allele is located on the sex chromosome. Males have only 1 X chromosome. So, a male who carries a recessive allele on the x chromosome will exhibit the sex linked trait. ...
Genes and Cleft Lip and Palate
Genes and Cleft Lip and Palate

... distressing for the person or their family to discover a wide variety of things that can go wrong in association with the syndrome. It is important to realise that no person with a syndrome has every feature: the list of features seen might be compiled from the summed experience of many people with ...
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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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