Nitrogenase is the enzyme used by some organisms to fix atmospheric nitrogen gas. It is only known family of enzymes which accomplishes this process.

Nitrogenase is the enzyme used by some organisms to fix atmospheric nitrogen gas. It is only known family of enzymes which accomplishes this process. Dinitrogen has a triple bond between nitrogen aoms. Nitrogenase thus breaks the triple bond by getting electron donors for each of the three bonds, and bonds the nitrogen to hydrogen atoms. The process is complex because each bond Is broken individually. Nitrogenase requires both the MoFe protein and ATP which supplies the energy. Nitrogenase bonds each atom of nitrogen to three atoms of hydrogen to form ammonia or NH3 each time nitrogenase associates with a second protin and each cycle transfers one electron from an electron donor which is enough to break one of the nitrogen chemical bonds. The enzyme is composed of the heterotetrameric MoFe protein that is transiently associated with the homodimeric Fe protein. Nitrogenase is supplied reducing power when it associates with the reduced, nucleotide-bound homodimeric Fe rotein.

 Azospirillum, a bacterium, growing on root surface of several tropical grasses, also fixed nitrogen. This combination where the nitrogen fixing micr

Ø Azospirillum, a bacterium, growing on root surface of several tropical grasses, also fixed nitrogen. This combination where the nitrogen fixing microbe does not penetrate deep into the host tissues is known as associate symbiosis.

Ø The first species of Rhizobium, R. Leguminosarum was identified in 1889, and all further species were placed in the genus Rhizobium

Ø Anammox – acronym for anaerobic ammonium oxidation- is the latest addition to the knowledge on the nitrogen cycle. In this biological process, nitrite and ammonium are converted directly into dinitrogen gas. This process makes up a mojor proportion of dinitrogen gas produced in the oceans.

Ø Although by far the majority of nitrogen – fixing plants are in the legume family Fabaceae, there are a few non-leguminous plants that can also fix nitrogen. These plants, referred to as actinorhizal plants, consist of 22 genera of woody shrubs or trees scattered in 8 plant families.

The RNA world hypothesis is a theory which proposes that a world filled with RNA based life existed before the current DNA based life, RNA which can s

The phrase “RNA world” was first used by walter gilbert in 1986. however the idea of independent RNA life is older and can be found in carl Woese’s The Genetic Code.The RNA world hypothesis is a theory which proposes that a world filled with RNA based life existed before the current DNA based life, RNA which can store information like DNA and catalyze reactions like proteins may have supported cellular or pre cellular life. Some theories as to the biogenetic origin of life state RNA based catalysis and information storage as the first step in the evolution of cellular life.

Chromatography: Chromatography is employed for identification, purification and for separation of the constituents of a mixture present in very small

Chromatography: Chromatography is employed for identification, purification and for separation of the constituents of a mixture present in very small amounts।

Crystallisation: Crystallisation is used to purify the compound when the compound and the impurities differ in their solubilities in a particular solvent।

Differential extraction: Differential extraction is used for extracting a compound if it is present in very small amount in an aqueous solution।

Paper chromatography: The analysis of unknown substances by the flow of solvent in a filter paper is known as paper chromatography।

Steam distillation: Steam distillation is used for separating/ purifying liquids which are immiscible with water, volatile in steam and have high vapour pressure।

Sublimation: Sublimation process is used for those compounds which are easily sublimed off.

GM crops are grown commercially or in field trails I over 40 countries and 6 continents. In 2000, about 109.2 million acres were planted with transgen

GM crops are grown commercially or in field trails I over 40 countries and 6 continents. In 2000, about 109.2 million acres were planted with transgenic crops, the principal ones being herbicide and insecticide-resistant soybeans, com cotton, and canola. Other crops grown commercially or field-tested are sweet potato resistant to a virus that could decimate most of the African harvest rice with increased iron and vitamins that may alleviate chronic malnutrition in Asian countries, and a variety of plants able to survive weather extremes.

On the horizon are bananas that produce human vaccines against infectious diseases such as hepatitis B; fish that mature more quickly fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties.

Although biotechnology and genetic modification commonly are used interchangeably. GM is a special set of technologies that alter the genetic makeup o

Although biotechnology and genetic modification commonly are used interchangeably. GM is a special set of technologies that alter the genetic makeup of such living organisms as animals plants, or bacteria. Biotechnology, a more general term, refers to using living organisms or their components, such as enzymes, to make products that include wine, cheese , beer, and yogurt.

Combining genes from different organisms is known as recombinant DNA technology, and the resulting organism is said to be genetically modified, “genetically engineered” or transgenic.” GM products include medicines and vaccines, foods and food ingredients, feeds and fibers.

Locating genes for important traits-such as those conferring in sect resistance or desired nutrients is one of the most limiting steps in the process. However, genome sequencing and discovery programs for hundreds of different organisms are generating detailed maps along with data analyzing technologies to understand and use them.

Since it is evident that control crosses that can be performed in pea plant or some other organisms, are not possible in case of human beings, study o

The idea that disorders are inherited has been prevailing in the human society since long. This was based on the heritability of certain characteristic features in families. After the rediscovery of Mendel’s work the practice of analyzing inheritance pattern of traits in human beings began. Since it is evident that control crosses that can be performed in pea plant or some other organisms, are not possible in case of human beings, study of the family history about inheritance of a particular trait provides an alternative.

Such an analysis of traits in several of generations of a family is called the pedigree analysis. In the pedigree analysis the inheritance of a particular trait is represented in the family tree over generations. In human genetics, pedigree study provides a strong tool, which is utilized to trace the inheritance of a specific trait abnormality or disease.

This inborn error of metabolism is also inherited as the autosomal recessive trait. The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney.

Uncondensed DNA can be transcribed but the condensed DNA heterochromatin cant be transcribed

• Uncondensed DNA can be transcribed but the condensed DNA heterochromatin cant be transcribed
• Histone interacts with DNA by salt bridges
• Plants in general have large sized chromosomes in comparison to animal, further the monocot plant have larger chromosome than the dicotyledons.
• Chromatid and chromonema are two names for the same structure. A chromonema represents a chromatid in the early stages of condensation.
• Chromosomes are stained with basic stains Orcein, Giemsa and Acetocarmin.

Mendelian crosses and ratios. A cross in which only one pair of contrasting characters is considered known as monohybrid cross. The progeny in F2 gen

Mendelian crosses and ratios.

A cross in which only one pair of contrasting characters is considered known as monohybrid cross. The progeny in F₂ generation appears in the phenotypic ratio of 3:1

If more than two pairs of contrasting characters are considered then such cross is called dihybrid cross. The progeny in F₂ generation appears in the phenotypic ratio of 9:3:3:1

Modern human evolved later, perhaps as little as 200,000 years ago. Their origins were in the Africa 100,000 years ago they began to move out of Afric

Modern human evolved later, perhaps as little as 200,000 years ago. Their origins were in the Africa 100,000 years ago they began to move out of Africa. These people eventually spread across the globe. As their territories expanded, the earlier human species that lived in Europe and Asia, gradually became extinct.

Charles Darwin was an English naturalist whose theory of evolution is one of the greatest contributions ever made to science. Darwin stated this theory in his book The Origin of Species. In another book called The Descent of Man he applied his theory to the evolution of man from a primitive monkey like animal.

Arica is the cradle of human race. Anthropologists have unearthed the oldest human skeletons in East Africa in places such as Hadar, Olduvai, Laetoli. One of the best preserved human remnants is a female skeleton found at Hadar in Ethiopia. Anthropologists assembled about 40% of the young girl that was given the nick name “LUCY”. Lucy was dated between 3.6 and 3 million years ago and belongs the Australopethicus category.

Hominin – the group consisting of modern human, extinct human species and all our immediate ancestors including members of the genera Homo, Australopithecus, Paranthropus and Ardipithecus.

A cryptic species complex is a group of species that satisfy the scientific definition of species that is , they are reproductively isolated from each

A cryptic species complex is a group of species that satisfy the scientific definition of species that is , they are reproductively isolated from each other but are not morphologically distinguishable. The individual species within the complex can only be separated using non-morphological data such as from DNA sequence analysis, bioacoustics, or thorough life history studies. They can, but need not be, parapatric, quite often are sympatric, and sometimes allopatric.

Examples :- Gray-cheeked Thrush and Bicknell’s Thrush.

Horizontal gene transfer or lateral gene transfer: In some organisms like bacteria, variation may result from horizontal gene transfer.

Horizontal gene transfer or lateral gene transfer:

In some organisms like bacteria, variation may result from horizontal gene transfer. This is a process in which an organism transfers genetic material to another cell that is not its offspring. By contrast, vertical transfer occurs when an organism receives genetic material from its ancestor, its parent or a species from which it evolved. Horizontal gene transfer is a significant phenomenon. Artificial horizontal gene transfer is a form of genetic engineering.

The phenomenon appears to have had some significance for unicellular eukaryotes as well. There is some evidence that even higher plants and animals have been affected. Horizontal gene transfer is common among bacteria, even very distantly related ones.

This process is thought to be a significant cause of increased drug resistance, when one bacterial cell acquires resistance, it can quickly transfer the resistance genes to many species.

There are majorly three processes for horizontal gene transfer in bacteria, transduction, transformation and conjugation. Horizontal gene transfer is a potential confounding factor in inferring phylogenetic tress based on the sequence of one gene. For example, given two distantly related bacteria that have exchanged a gene, a phylogenetic tree including those species will show them to be closely related because that gene is the same, even though most other genes have substantially diverged.

The RNA world hypothesis is a theory which proposes that world filled with RNA based life predates current DNA based life.

The RNA world hypothesis is a theory which proposes that world filled with RNA based life predates current DNA based life. RNA, which can store information like DNA and catalyse reactions like proteins, may have supported cellular or pre-cellular life. The RNA world hypothesis is supported by RNA’s ability to store, transmit andduplicate genetic information, as DNA does. RNA can also act as a ribozyme and enzyme made of ribonucleic acid. Because it can reproduce on its own, performing the tasks of both DNA and proteins enzymes, RNA is believed to have once been capable of independent life.

Our present atmosphere consists of 78% nitrogen, 21% molecular Oxygen and 1% of other gases, such as Carbon Dioxide, Argon and water Vapour. An atmosp

• Our present atmosphere consists of 78% nitrogen, 21% molecular Oxygen and 1% of other gases, such as Carbon Dioxide, Argon and water Vapour. An atmosphere containing free oxygen would be fatal to all origin of life schemes.
• While oxygen is necessary for life, free oxygen would oxidize and thus destroy all organic molecules required for the origin of life. Thus, in spite of much evidence that the Earth has always had a significant quantity of free Oxygen in the Earth’s early atmosphere. However, this would also be fatal to an evolutionary origin of life.
• If there were no Oxygen there would be no protective layer of Ozone surrounding the earth. Ozone is produced by radiation from the sun on the Oxygen in the atmosphere, converting the diatomic Oxygen we breathe to triatomic Oxygen which is Ozone. Thus, if there were no Oxygen there would be no Ozone.