Monthly Archives: October 2019

Cytotaxonomy: Study of Chromosome Behaviour

Chromosome behavious is an important factor that determine the pattern of variation and taxonomic distinctness.Pairing behavior and subsequent separation of chromosome occurs at meiosis. In reporting results of pairing studies, univalents are represented by I, bivalents by II, etc. Some taxonomic information can be gained from the study of mechanism …

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Cytotaxonomy: Study of Chromosome Structure

Study of chromosome structure is very important in cytotaxonomic studies. It includes chromosome size, shape and position of centromere (i.e. arm-length ratio of each chromosome in the genome) Chromosomal size and shape are also important as taxonomic criteria in taxonomy. For examples, The chromosomal ratio if Mediola and Trillium of …

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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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Chromosome Number: A Great Tool in Taxonomic Studies

Taxonomy – is the branch of biology that deals with identification, nomenclature and classification of an object. Cytology – is the branch of biology that deals with origin, structure and function of cell. So Cytotaxonomy presumably means the application of cytological data to taxonomy. More precisely we can say Cytotaxonomy …

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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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Genetic Code

The four bases in DNA – A, T, G, and C are sufficient to specify the 20 amino acids in proteins because each codon is three bases in length. Each sequence of three adjacent bases in mRNA is a codon that specifies a particular amino acid (or chain termination). The …

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Cronquist’s System of Classification

Arthur Cronquist was the Senior Curator of New York Botanic Garden and Adjunct Professor of Columbia University. He presented an elaborate interpretation of his concept of classification in The Evolution and Classification of Flowering Plants (1968), The further edition of his classification was published in “An Integrated System of Classification …

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Phylogenetic Classification of John Hutchinson

John Hutchinson was a British botanist associated with Royal Botanic Gardens, Kew, England. He developed and proposed his system based on Bentham and Hooker and also on Bessey. His phylogenetic system first appeared as “The Families of Flowering Plants in two volumes. The first volume contains Dicotyledons (published in 1926) …

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