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

Protein case study, DK is a year old female who was born after a normal pre...

DK is a year old female who was born after a normal pregnancy and delivery.  At 17 months of age DK showed signs of speech delay, increased lethargy and vomiting up to four times p

What is vaso-constriction, a) What is 'vaso-constriction'? b) W...

a) What is 'vaso-constriction'? b) What are the effects of vaso-constriction in the skin?   a) Vaso-constriction is the reduce in diameter of small arterioles an

Show overall management of diabetes, Q. Show overall management of diabetes...

Q. Show overall management of diabetes? Diabetes as we all know is a disease with ever increasing prevalence in' our country. It can be described as a disease characterized by

What are the benefits of migration, What are the Benefits of migration ...

What are the Benefits of migration Eg: Need to leave Alaska due to harsh weather conditions (statement that birds are escaping NZ winter not acceptable). Longer day

What are the advantages of intra oral periapical radiographs, Advantages of...

Advantages of Intra Oral Periapical Radiographs a) It is a useful high yield modality for ruling out local bone or dental disease b)  It is of value in identifying critical

Explain growth of pluricellular organisms, Q How does mitosis participate i...

Q How does mitosis participate in the growth of pluricellular organisms? All pluricellular beings grow with the raise in quantity of their cells. This raise is produced by mito

Theoretical foundation of halsted reitan battery, Theoretical Foundation of...

Theoretical Foundation of Halsted Reitan battery There are really two theoretical bases for the Halsted Reitan battery, one contained in brain and intelligence and related writ

ASSINMENT, HISTORY ON CLASSIFICATION IN BIOLOGY

HISTORY ON CLASSIFICATION IN BIOLOGY

Explain heat preservation - method of food preservation, Explain Heat Prese...

Explain Heat Preservation - Method of Food Preservation? The process of heating was used centuries before its action was understood. Food is heated up or cooked. Heat kills mi

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