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Chromosomes are very large DNA strands that contain many genes. During mitosis (cell division), the chromosomes are condensed and called metaphasic chromosomes. They are the only state in which DNA is visible with an optical microscope. In eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it is wrapped around histones (structural proteins, Fig. 1), and is called chromatin; prokaryotes do not possess histones. In its relaxed state, the DNA can be accessed for transcription, regulation, and duplication. Chromosomes were discovered by [Karl von Naegli]? in 1842. In 1910, [Thomas Hunt Morgan]? proved chromosomes to be the carriers of genes. |
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Chromosomes are very large DNA strands that contain many genes. During mitosis (cell division), the chromosomes are condensed and called metaphasic chromosomes. They are the only state in which DNA is visible with an optical microscope. In eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it is wrapped around histones (structural proteins, Fig. 1), and is called chromatin; prokaryotes do not possess histones. In its relaxed state, the DNA can be accessed for transcription, regulation, and duplication. Chromosomes were discovered by [Karl von Naegli]? in 1842. In 1910, [Thomas Hunt Morgan]? proved chromosomes to be the carriers of genes. |
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In the early stages of mitosis, the chromatin strands become more and more condensed. They cease to function as accessible genetic material and become a compact transport form. Eventually, the two matching chromatids? (condensed chromatin strands) become a chromosome, linked at the centromere. Long microtubules are attached at the centromere and two opposite ends of the cell. During mitosis, the microtubules pull the chromatids apart, so that each daughter cell inherits one set of chromatids. Once the cells have divided, the chromatids are uncoiled and can function again as chromatin. In spite of their appearance, chromosomes are well structured (Fig. 2). For example, genes with similar functions are often close together in the chromosome, but not in the linear DNA. The short arm of a chromosome can be extended by a [satellite chromosome]? that contains codes for ribosomal RNA. |
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In the early stages of mitosis, the chromatin strands become more and more condensed. They cease to function as accessible genetic material and become a compact transport form. Eventually, the two matching chromatids? (condensed chromatin strands) become a chromosome, linked at the centromere. Long microtubules are attached at the centromere and two opposite ends of the cell. During mitosis, the microtubules pull the chromatids apart, so that each daughter cell inherits one set of chromatids. Once the cells have divided, the chromatids are uncoiled and can function again as chromatin. In spite of their appearance, chromosomes are well structured (Fig. 2). For example, genes with similar functions are often close together in the chromosome, but not in the linear DNA. The short arm of a chromosome can be extended by a [satellite chromosome]? that contains codes for ribosomal RNA. |
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**[Klinefelter syndrome]? (XXX or XXY). Men with Klinefelter syndrome are usually sterile. They tend to have longer arms and legs and tend to be taller than their peers. Other common symptoms are lack of emotion, fatigue, apathy and an increased tendency to develop psychiatric disorders. |
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**Klinefelters Syndrome (XXX or XXY). Men with Klinefelter syndrome are usually sterile. They tend to have longer arms and legs and tend to be taller than their peers. Other common symptoms are lack of emotion, fatigue, apathy and an increased tendency to develop psychiatric disorders. |
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You can find a detailed graphical display of all human chromosomes and the diseases annotated at the correct spot at [1]. |
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