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Reverse Transcription Basics The process of creating DNA from an RNA template is known as reverse transcription. Reverse transcriptases, or RNA-dependent DNA polymerases, are the enzymes that propel this process.  Reverse transcriptases are found in retroviruses and prokaryotic and eukaryotic organisms in their natural states. When a viral particle enters a target cell's cytoplasm, reverse transcription starts. As a component of an as-yet-uncharacterized nucleoprotein complex, the viral RNA genome penetrates the cytoplasm. Through a complex set of steps, reverse transcription creates a linear DNA duplex in the cytoplasm. Although the DNA and its RNA template are colinear, the DNA has terminal duplications called long terminal repeats (LTRs) that are absent from viral RNA.  Current reverse transcription models suggest that in order to produce the LTRs, two specific template switches called "jumps" or strand-transfer reactions are needed. The two unique enzymatic activities...

Evolution of sex in algae : An overview  In plants, asexual and sexual reproduction are the two main modes of reproduction. Asexual reproduction does not entail sex and does not involve the fusing of any kind of cell or gamete. Spores are a unique form of cell that reproduces in this manner. Every one of these spores has the ability to grow into a new plant. In contrast, when two cells, or gametes, combine during sexual reproduction, a zygote is created that eventually grows into a new plant. Without fusing, individual gametes are normally unable to create new plants. Origin of sex:  The most primitive algae, such as those belonging to the Cyanophyceae (Myxophyceae) family, such as Gloeocapsa and Chroococcus, reproduce by fusion, whereas Oscillatoria, Nostoc, and Anabaena, among others, reproduce vegetatively through the division of a small group of cells known as hormogonia, which subsequently gives rise to new plants through additional division. Certain Cyanophyceae members ...

  Importance of cell wall in prokaryotic cell wall: A cell wall is defined as the non-living component, covering the outmost layer of a cell. Its composition varies according to the organism and is permeable in nature.   All prokaryotic cells have a stiff cell wall, located underneath the capsule (if there is one). This structure maintains the cell shape, protects the cell interior and prevents the cell from bursting when takes up the water.  The main function of the cell wall is to provide structural strength and support, and also provide a semi-permeable surface for molecules to pass in and out of the cell. The cell wall in bacteria is essential for survival as it helps to keep the contents of the cell intact. Antibiotics usually work on this principle by targeting the bacterial cell wall and causing lysis. This leads to the expulsion of cellular contents and the eventual death of the cell. Importance of cell wall in Eukaryotic cell wall:      A typi...

Retrovirus  - an overview Retroviruses are viruses whose genetic material is RNA. They are retroviruses that are members of the Retroviridae family. After infecting a cell, it uses reverse transcription to change the RNA therein into DNA. After that, the host cell's DNA is exposed to this viral DNA, and it begins to replicate there. The Human Immunodeficiency Virus (HIV), for instance. Structure of Retroviruses Meaning of a retrovirus: A class of RNA viruses that replicate by introducing a DNA copy of their genome into their host cell. The envelope protein complex is embedded in the lipid bilayer, which is composed of two concentric outer circles. Hexagonal proteins make up capsids. The RNA genome is replicated in a loop that is held together by nucleoproteins.   The principal parts of a virion are: Wallet Env genes encode glycoproteins and lipids that make up the retroviral envelope. It fulfills three crucial purposes: Envelope  Env genes encode glycoproteins and lipids ...

  Merits and Demerits of Numerical Taxonomy  The process of categorizing organisms using numerical techniques is known as numerical taxonomy. This method firmly clarifies as well as displays the degree of link among the species. Organisms are classified into taxa according to their similarities and differences.  Numerical Taxonomy is at present a very essential part of current systematics. Numerical Taxonomy is also known as Taximetrics; however, presently it is more commonly referred to as Phenetics. It is the Numerical evaluation of the similarities or affinities of taxonomic units, which are typically classified into taxa based on their affinities.  It is also known as Adansonian taxonomy or phenetics.  Robert Sokal and Peter Sneath defined numerical taxonomy.  It is a method of classifying organisms with the help of numerical methods.  In this type of taxonomy, each character is given equal weightage in creating new taxa.  The phenetic similar...