From molecules to the first cell, Biology

Assignment Help:

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


Related Discussions:- From molecules to the first cell

How is fecundation done in insects, Q. How is fecundation done in insects (...

Q. How is fecundation done in insects (internal or external)? Is there copulation between insects? Fecundation in insects is internal, with copulation.

Illustrate goal of modern dentistry, Q. Illustrate goal of modern dentistry...

Q. Illustrate goal of modern dentistry? The goal of modern dentistry is to restore the patient to normal contour, comfort, function, esthetics, speech and health regardless of

What does the formula dpd = sf - tp mean, What does the formula DPD = SF - ...

What does the formula DPD = SF - TP mean? DPD is the abbreviation of diffusion pressure shortage, SF (suction force) is the vacuolar osmotic pressure and TP is the turgor press

How does the Cornea work, How does the Cornea work, I heard that it is like...

How does the Cornea work, I heard that it is like a motor, however i''m not too sure... because a motor is in vehicle and has piston, and the Cornea is in our eyes and... Well does

Response to wounding, Response to Wounding Wounding of tomato plants b...

Response to Wounding Wounding of tomato plants by mechanical injury or chewing by insects releases a factor that triggers accumulation of two proteinase inhibitors-throughout

Define protein as an energy source, Define Protein as an energy source? ...

Define Protein as an energy source? Proteins contribute to the body's energy need. If diet does not furnish enough calories from carbohydrates and fats, proteins are catabolize

What is signifying by suction force of the plant cell, Q. What is signifyin...

Q. What is signifying by suction force of the plant cell? Does the suction force facilitate or make difficult the entry of water into the cell? The suction force (SF) is the os

Tisues, digram or mammalian testis

digram or mammalian testis

Tissue culture, Note on production of haploid by tissue culture.

Note on production of haploid by tissue culture.

What are the dominate phenotype, There is a population of 100 frogs. 20 are...

There is a population of 100 frogs. 20 are heterozygotes, 30 are homozygous recessive, 25 are homozygous dominate. What is the frequency of the dominate allele? The recessive allel

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd