Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
From Molecules to the First Cell
The prebiotic conditions on the earth in all probability were volcanic eruptions, lightning and heavy rains. There was no trace of free oxygen or an ozone layer in the atmosphere to absorb ultraviolet radiations from the sun. It is assumed that organic molecules would have originated in such climatic conditions. This is described as their abiotic origin. Laboratory experiments from 1953 onwards prove that organic molecules like amino acids, proteins, nucleotides, nucleic acids, lipids and ATP can be formed in similar conditions on the earth. Stan1r.y Miller's experiment described below is one such experiment (Fig. shown below). It is possible that such organic molecules similar to those synthesised in Miller's experiment would have got accumulated at several places in high concentration, giving rise to a kind of liquid soup.
Scientists have three different speculatiohs about the composition of a protobiont. Some consider it'as an aggregate of electrically charged molecules with water around them acting as a boundary and this is called as coacervate model (Fig. shown below). This model was proposed by Alexander Oparin. Sidney Fox proposed another model for protobiont formation called protenoid microsphere model. According to this model when water free mixtures of amino acids are heated at high temperature, they pol.yinerise to form protein-like molecules, called proteinoids. These can persist only if cooled quickly. According to a third model called as the lipid bilayer model of Richard Goldacre, an abiotically synthesised phospholipid bilayer was formed around a central space containing organic molecules. All such models are without any experimental or theoretical evidence. However, the supporters of each model try to explain how some life-processes like osmosis and budding, can be camed out by such protobionts.
Mechanism of Enzyme Action The action of enzymes is to lower the activation energy or threshold of their substrates which. Therefore become activated and react with
"Height" is an example of a gene, but "Short" is an example of...
Explain Some Functions of Riboflavin? Protective role: Riboflavin protects the octodermal tissues and prevents lesions of the skin, eye and nervous system. Riboflavin amelior
Haustorial Behavior of Embryo Sac There are instances in which the entire embryo sac may grow beyond the ovular tissue. The central cell may also form multicellular projectio
Describe cardiac rewabilptation and its various effects ? A survival benefit cannot be attributed solely to exercise training because many studies involved multifunctional inte
Explain about the Weight cycling - energy balance? There are a number of obese people who keep losing and gaining weight a number of times in their lives. This is called the Yo
Meteorological Factors and Air Pollution Air pollution levels in a region are affected by wind, location, topography, precipitation and temperature inversions. Wind can carry
Q. What are diseases of the connective tissue? What are some of them? Diseases of the connective tissue are acquired or hereditary diseases numerous of autoimmune cause charact
Corpus Allatum and Juvenile Hormone The corpora allata are rounded glands attached to the posterior side of every corpus cardiacum making a compact body just behind the brain.
Unsaturated fatty acids Unsaturated fatty acids are liquid at room temperature and are characterized by having one or more double bonds. Fatty acids having two or more
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd