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Classic Layout

Polysaccharides: The Long Chain of Simple Sugars

Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide unit bound together by glycosidic linkage. Example: starch, glycogen, cellulose, chitin etc. Characteristics of polysaccharide On hydrolysis, they yield monosaccharide units which are usually similar. D glucose is the commonest component of polysaccharide. They have high molecular weight. They …

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Disaccharides: Bonding of Two Simple Sugars

A disaccharide, also called double sugar, is the sugar formed when two monosaccharides (simple sugars) are joined by a glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose, and maltose. Disaccharides are one of the four chemical groupings of carbohydrates (monosaccharides, disaccharides, oligosaccharides, and polysaccharides). The most common …

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Transposable Genetic Elements

Transposons were first discovered in corn (maize) during the 1940s and ’50s by American scientist Barbara McClintock, whose work won her the Nobel Prize for Physiology or Medicine in 1983. The colourful pattern on maize ears have an important scientific significance. Modern research have shown that the stripes and spots …

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DNA Replication in Eukaryotes: Linear Replication

DNA replication in eukaryotes is a complex and unique process involving many enzymes and thousands of ORI at a single time. Unlike the prokaryotic DNA, it involves a linear mode of replication. Why does linear DNA replication involve  multiple origins at a time? The large linear chromosomes in eukaryotic cell …

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Replication in Circular DNA: Theta Model

Following Meselson and Stahl’s work, investigators confirmed that other organisms also use semiconservative replication. There are, however, several different ways that semiconservative replication can take place, differing principally in the nature of the template DNA—whether it is linear or circular—and in the number of replication forks. Replicon and Origin of …

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Translation: mRNA to Protein

Translation takes place on ribosomes; indeed, ribosomes can be thought of as moving protein-synthesizing machines. A ribosome attaches near the 5′ end of an mRNA strand and moves toward the 3′ end, translating the codons as it goes. Synthesis begins at the amino end of the protein, and the protein …

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Post-transcriptional Modification

The process of transcription is very similar in prokaryotes and eukaryotes, but there are major differences in the relation between the transcript and the mRNA used for polypeptide synthesis in eukaryotes. In prokaryotes, the immediate product of transcription (the primary transcript) is mRNA; by contrast, the primary transcript (also called …

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