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.

1714_protobionts.jpg

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
Q. Can you explain Salmonellosis Salmonellosis is a common food bome disease all over the world. There are approximately 1600 different strains (sero types) of Salmonell

What are the chemical elements that form most of living biological matter? The elements are:- a)  oxygen (O), b)  carbon (C), c)  hydrogen (H) and d) Nitrogen (N).

Amantadine Treatment with oral amantadine or rimantadine begun within 48 hours after the onset of illness decreases the duration of fever and symptoms by about 1 day. Whether t

Floristic Composition - Qualitative Characters One of the important qualitative characteristics of a community is its floristic composition. This broadly refers to the kind o

Autophagic intracellular digestion is the cellular internal digestion of waste and residual materials. In general it is completed by lysosomes. Autophagic intracellular digestio


FUNCTIONS OF SKELETON - 1.      Support. 2.      To give shape to the body. 3.      Protection of different organs. 4.       Site for muscle attachment. 5.       He

Reversible airways obstructive disease, advanced heart block, or episodic decompensation.  Vasodilators Agents that dilate arteriolar smooth muscle and lower peripheral vascu

The biosphere is composed of all living organism. This sphere includes all the microorganism, plants and animals of earth. In fact biosphere involves interaction of living beings w

Phases of Karyokinesis: Karyokinesis can further be divided into prophase, metaphase, anaphase and telophase. 1-Prophase: (pro= before) Chromatin: During Interphase (non