From molecules to the first cell, Biology

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.

2287_molecule to 1st cell.jpg

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.


Posted Date: 12/8/2012 7:48:16 AM | Location : United States

Related Discussions:- From molecules to the first cell, Assignment Help, Ask Question on From molecules to the first cell, Get Answer, Expert's Help, From molecules to the first cell Discussions

Write discussion on From molecules to the first cell
Your posts are moderated
Related Questions
Which are the subproducts of the photochemical stage that are essential for the chemical stage of photosynthesis? The chemical stage of photosynthesis depends on NADPH and ATP

Q. What is the relationship between enzyme and vitamins cofactors? Many vitamins are enzyme cofactors that cannot be synthesized by the organism and must be acquired from the d

Aeolian Wind transported materials constitute this category. This can be further divided into dunes or loess. Dunes are found in thr& types of situations. Fitly, these may occu

What is the relation among fecundation and the end of the meiotic process during oogenesis? The oocyte II only completes the second meiotic division (interrupted at metaphase) i

Define volumetric flasks - Nutritional Biochemistry A volumetric flask is used to make up a solution of fixed volume very accurately. It is calibrated to contain a particular v

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Is the transportation of gases in tracheophytes made through the vascular tissues? The Carbon dioxide and The Oxygen are not transported through the xylem or phloem. These gase

Oxygen is a major component of all living organisms. All the organisms and plants required oxygen for aerobic respiration which they absorb from environment. Only plants release ox

Q. Can Diseases be etiological factor for diabetes? Diseases: In aging, a very important cause of diabetes could be an underlying disease. Diabetes occurs secondary lo some ot

Air pollution affects both living and non-living matter. The effects can be classified as.