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Case Study Learning via Simulations of Molecular Biology Techniques
Case Study Learning via Simulations of Molecular Biology Techniques

... The disease is multifactorial and inheritance patterns are complex. Some forms of familial Alzheimer disease appear to be inherited as autosomal dominant traits, while others are recessive. Spontaneous Alzheimer disease also can occur in the absence of inherited factors. Mutations in at least four g ...
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Understanding Genetics: Punnett Squares
Understanding Genetics: Punnett Squares

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Electrokinetic Stretching of Tethered DNA
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FREE Sample Here
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... Ans: Meselson and Stahl grew bacteria in the presence of 15N, or “heavy” nitrogen. They rapidly replaced the 15N media with 14N, or light nitrogen. DNA was extracted at various time intervals during the growth of the bacteria, representing different stages of replication (generations). They examined ...
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Enzyme Mechanisms - Illinois Institute of Technology
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Designing a single-molecule biophysics tool for characterizing DNA

... Two common assays for in vivo and in vitro quantification of DNA damage work via electrophoresis. DNA is negatively charged and so will migrate through a porous medium when a potential difference is applied. In electrophoresis the distance travelled by a particular fragment depends on both its molec ...
DNA sequence representation by trianders and determinative
DNA sequence representation by trianders and determinative

... nucleotides have an inner abstract characteristic, the determinative degree, which reflects genetic code phenomenological properties and is adjusted to nucleotides physical properties. We consider each codon position independently, which gives three separate walks characterized by different angles a ...
here
here

... mostly very similar. In order for this to happen, the complementary base pairings that occur in prokaryotes and eukaryotes must also be very similar. This means that the structure of the DNA (in terms of the complementary base pairs) of eukaryotes and prokaryotes are very similar. ...
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Nucleosome



A nucleosome is a basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around eight histone protein cores. This structure is often compared to thread wrapped around a spool.Nucleosomes form the fundamental repeating units of eukaryotic chromatin, which is used to pack the large eukaryotic genomes into the nucleus while still ensuring appropriate access to it (in mammalian cells approximately 2 m of linear DNA have to be packed into a nucleus of roughly 10 µm diameter). Nucleosomes are folded through a series of successively higher order structures to eventually form a chromosome; this both compacts DNA and creates an added layer of regulatory control, which ensures correct gene expression. Nucleosomes are thought to carry epigenetically inherited information in the form of covalent modifications of their core histones.Nucleosomes were observed as particles in the electron microscope by Don and Ada Olins and their existence and structure (as histone octamers surrounded by approximately 200 base pairs of DNA) were proposed by Roger Kornberg. The role of the nucleosome as a general gene repressor was demonstrated by Lorch et al. in vitro and by Han and Grunstein in vivo.The nucleosome core particle consists of approximately 147 base pairs of DNA wrapped in 1.67 left-handed superhelical turns around a histone octamer consisting of 2 copies each of the core histones H2A, H2B, H3, and H4. Core particles are connected by stretches of ""linker DNA"", which can be up to about 80 bp long. Technically, a nucleosome is defined as the core particle plus one of these linker regions; however the word is often synonymous with the core particle. Genome-wide nucleosome positioning maps are now available for many model organisms including mouse liver and brain.Linker histones such as H1 and its isoforms are involved in chromatin compaction and sit at the base of the nucleosome near the DNA entry and exit binding to the linker region of the DNA. Non-condensed nucleosomes without the linker histone resemble ""beads on a string of DNA"" under an electron microscope.In contrast to most eukaryotic cells, mature sperm cells largely use protamines to package their genomic DNA, most likely to achieve an even higher packaging ratio. Histone equivalents and a simplified chromatin structure have also been found in Archea, suggesting that eukaryotes are not the only organisms that use nucleosomes.
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