Cytology

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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Chromosomal Aberration: Structural and Numerical

What is Chromosomal Aberration? Any type of change in the structure and number of chromosomes due to certain irregularities during cell division is known as chromosomal aberration. Broadly such aberrations are divided into two major groups. Structural aberration Numerical aberration Again, structural aberrations are of 4 types. Such as: Deletion …

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Solenoid Model: The Second Level of Packing

In the nucleosome model of chromosome, we have discussed about the fundamental organizational unit of chromosome termed as nucleosome. That article gave us a simplistic idea about how the repeated nucleosomes are arranged. The figure in the right hand side clarifies that the nucleosome model provides us with the insight …

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Nucleosome Model of Chromosomes

Let’s kick off this discussion with a simple calculation about the length of DNA in a single diploid human cell. We know according to Watson and Crick model of double helix DNA, each two base pairs has a distance of 3.4 A. There are approximately 6.4 billion base pairs (bp) …

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Programmed Cell Death

The acronym of PCD is Programmed Cell Death. The death of a cell in any form, mediated by an intracellular program is called programmed cell death. PCD is carried out in a biological process, which gives advantage during an organism’s life cycle. History The concept of PCD was used by …

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