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

What is the ranges of tolerance and performance optima, What is the ranges ...

What is the ranges of tolerance and performance optima? Ranges of Tolerance and Performance Optima :   When it comes to physical factors or resources, most species are able to

Meiosis, Why is it necessary to have the second division in meiosis even th...

Why is it necessary to have the second division in meiosis even though cells have already been reduced to haploid number after the first division?

Care of psychoemotional aspects of patient in icu, Care of Psychoemotional ...

Care of Psychoemotional Aspects ICU area is an area which is cut off from outside world. Modem ICUs are built in such a way that the sensory deprivation is reduced. Ta

To study whether bacteria grow best where it is moist or dry, To study whet...

To study whether bacteria grow best where it is moist or dry Use 2 sterile dishes. Inoculate each one by touching a sterile transmit needle to a bacteria colony rowing in anoth

How are ecological interactions classified, Q. How are ecological interacti...

Q. How are ecological interactions classified? Ecological interactions are classified as interspecific or intraspecific interactions and as harmonious or inharmonious interacti

Mosaic endosperm - variants of endosperm, Mosaic Endosperm - Variants of En...

Mosaic Endosperm - Variants of Endosperm In some plants patches of two different colors appear in the tissues of the endosperm providing a mosaic design. In maize, red and whi

The two regulation systems of glycogen metabolism, Mention the two regulati...

Mention the two regulation systems of glycogen metabolism. There is a hormonal regulation system functioning  in the muscle and liver which regulates  the glycogen metabolism.

What is probing depth, What is Probing depth Probing depths can be infl...

What is Probing depth Probing depths can be influenced by the tissue type- shallow depths are associated with a keratinized collar, whereas deeper depths are associated with mo

Determine the evaluation of the bone, Evaluation of the bone Evaluation...

Evaluation of the bone Evaluation of the bone -implant interface needs to be done by the following: Failures in Implant Dentistry 1) Implant mobility and discomfort 2)

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