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

Can pathophysiology causes cardiovascular disease, Q. Can Pathophysiology c...

Q. Can Pathophysiology causes cardiovascular disease? Cigarette use activates platelets, increases circulating fibrinogen, increases heart rate, and elevates blood pressure. It

The effect of light on the growth of stems, The effect of light on the grow...

The effect of light on the growth of stems (a)  Plant some seeds that grow rapidly like as oats, radish, bean or mustard seeds in two flower pots. When the seedlings are about

What are the advantages of panoramic x-ray, Advantages of Panoramic X-Ray ...

Advantages of Panoramic X-Ray  Opposing landmarks are easily identified  The vertical height of the bone initialy can be assessed  The procedure is performed with conveni

Respiratory system of the phylum annelida characterized, Q. How is the resp...

Q. How is the respiratory system of beings of the phylum Annelida characterized? Respiration in annelids can be branchial or cutaneous. Cutaneous respiration takes place due to

Centrifugal pump-type of blood pump, Centrifugal Pump: This is available ...

Centrifugal Pump: This is available for clinical perfusion from 1976 (Bio Medicus Pump). It is disposable, causes less blood trauma and reduces the risk of massive air embolism.

Write down a dna palindrome, Write a DNA palindrome or inverted repeat of a...

Write a DNA palindrome or inverted repeat of at least 10 nucleotides in length.

Was there molecular oxygen in the earths primitive atmospher, Was there mol...

Was there molecular oxygen in the earth's primitive atmosphere? How has that molecule become abundant? The presence of the molecular oxygen in the primitive atmosphere was prob

Explain feeding schedule in infancy, Explain Feeding Schedule in Infancy? ...

Explain Feeding Schedule in Infancy? 1) Milk feed 5-6 times/day. Continue breast-feeding. Exclusive breast-feeding up to 6 months even during illness. Follow demand feeding.

Explain the absorption of itraconazole capsules, Explain The absorption of ...

Explain The absorption of itraconazole capsules It is decreased with concurrent use of drugs that reduce gastric acidity, such as antacids, H2-receptor blockers, proton pump in

Define requirements for underwater weighing method, Define Requirements for...

Define Requirements for underwater weighing method? • The equipment required to perform hydrostatic measurements is bulky and maintenance intense. • A large tank of water, usu

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