Molecular biology signifies the intersection of biochemistry, genetics and cell biology. Even the molecular biology includes microbiology and virology. So molecular biology is frequently used as a catch-all, to describe a wide girth of interests.
Biogeography means the study of geographical distribution of species. The story of Darwin’s theory of natural selection begins in 1831, when he joined as an unpaid natur
alist on a five year navigational mapping expedition of the British Admiralry aboard the ship H. M. S. Beagle. During this voyage, Darwin observed and studied a wide variety of plants and animals on continents and islands of volcanic origin, the Galapagos islands, which lie on the equator about 900 kilometer off the West Coast of South America. There, he found giant tortoises, meter-long marine and land iguanas, many unusual plants, insects, lizards and sea shells. These is called evidence from bio geography.
The Galapagos islands consisted of twenty-two different islands that were only a few miles apart. Darwin noticed that the Galapagos islands have many endemic (native, found nowhere else) species of plants and animals. He was amazed to record that in the islands insect-eating warblers and woodpeckers were absent. Instead, various types of inches, a group of small black birds, which were originally seed-eating but have assumed insect-eating pattern, were present in the islands. These finches are often referred to as Darwin’s finches. He also observed that different geographical localities have similar habitats but house different species. The finches of different islands varied yet they were closely related to each other.
Why the plants and animal species of the islands are closely related to species of the nearest mainland or neighboring island? Why the islands contain more different species of finches than the entire South American continent? Darwin realized that such questions could be explained on the ground that from ancestral group, living in a particular geographical area, descendant populations could radiate into other areas, where the new environmental conditions brought about the suitable adaptation by evolution. He reasoned that after originating from a common ancestral seed-eating stock the finches radiated to different geographical areas and underwent profound adaptive changes, especially in the patterns of beak. Living in isolation for long period of time new kinds of finches emerged that could function and survive in the new habitats. Such an evolutionary process, giving rise to new species adapted to new habitats and ways of life, is called adaptive radiation.
Furthermore, Australia is the home to the great diversity of pouched mammals but relatively few placental mammals. Darwin explained that adaptive radiation gave rise to a variety of marsupials in Australia in the same process of adaptive radiation as found in the finches in the Galapagos Islands.
Natural selection can lead to similar adaptation for survival in the similar habitats. This form of evolutionary changes is called convergent or parallel evolution. For example, some of the marsupials of Australia resemble equivalent placental mammals that live in similar habitats of other continents. Australia separated from other continents more than 50 million years ago. Most likely, marsupials arrived in Australia before its separation from Antarctica and evolved in isolation earlier than placental mammals. Natural selection has favored changes that made the two groups more alike. In other words, their phenotypes have converged.
Furthermore, Australia is the home to the great diversity of pouched mammals but relatively few placental mammals. Darwin explained that adaptive radiation gave rise to a variety of marsupials in Australia in the same process of adaptive radiation as found in the finches in the Galapagos islands.
Natural selection can lead to similar adaptation for survival in the similar habitats. This form of evolutionary changes is called convergent or parallel evolution. For example, some of the marsupials of Australia resemble equivalent placental mammals that live in similar habitats of other continents. Australia separated from other continents more than 50 million years ago. Most likely, marsupials arrived in Australia before its separation from Antarctica and evolved in isolation earlier than placental mammals. Natural selection has favored changes that made the two groups more alike. In other words, their phenotypes have converged.
Harold C. lirey (1893•1981), an Astronomer, accorded the first adequate recognition of Opartn-Haldane’s view on the origin of life In 1952. Urey asked his student Stanely L. Miller, a biochemist, to replicate the primordial atmosphere as propounded by Opartn and Haldane. Miller (1953) made the first successful simulation experiment to assess the validity of the claim for origin of organic molecules in the primeval Earth condition. Miller sealed in a spark chamber a mixture of water H20, methane (CH4), ammonia (NH3) and hydrogen gas (h2). He made arrangement for insertion of two electrodes to provide electrical energy (Simulation of lightening) to the spark chamber. The spark chamber was connected to another flask with arrangement for boiling water (provision for evaporation). The other end of the spark chamber was connected to a trap by a tube that passed through a condenser (an arrangement for condensation and collection of aqueous solution, equivalent to rain and Haldane’s soup). The trap, in turn, was connected with the flask for boiling water (arrangement for circulation). The control apparatus contained every arrangement except that It was devoid of energy source.
Observation unveils that the diverse types of animals bear some common characters. For example, amphibians, reptiles and mammals have limbs for locomotion on land, fishes have fins for swimming in water, birds have wings for flying. A close scrutiny reveals that the limbs, fins and wings are fonned on the same basic structural plan. All such examples can be explained if we consider that the diverse groups of organisms share a common ancestor from whom they have diverged and fonned two different species. With the passage of time a single ancestral lineage (an evolutionary sequence. arranged in linear order from an ancestral group to a descendant group) has produced two or more lineage that diverged over time. Such process of change in biological system is called evolution. The world evolution means to unfold or unroll or to reveal hidden potentialities. In its broadest sense, evolution simply means an orderly ‘change’ from one condition to another. For Instance, the planets and stars change in between their birth and death. This is stellar evolution. The matters elements -change in time. This is Inorganic evolution. The changes in the properties of population of organisms or groups of such populations over the course of generations are considered as biological or organic evolution. It is a process of cumulative change of living populations and in the descendant populations of organisms. In other words, it is descent with modifications. In general, the diversities of life, including both the differences and similarities, and the characteristics of organisms, both adaptive and non-adaptive. These are the great themes of evolutionary biology. According to Theodosius Dobzhansky (I973), nothing in biology makes sense except in the light evolution.
Origin of life is inseparably linked with the origin of Earth. In fact, the history of life is a chronicle of a restless Earth. The Big Bang Theory proposes that the universe had an explosive beginning. Universe originated about 15 billion years ago by a bigbang (thermonuclearexplosion) of a dense entity. About 4.5 billion years ago, our solar system was probably created when the gaseous cloud called solar nebula started to collapse under the force of Its own gravity until it became a flattened spinning disc of atoms and particles. Its central region heated up and became a star. The Sun. Atoms and the dust grains orbiting the centre of the gaseous disc then aggregated into clumps {about the size of asteroids), These clumps finally swept up all particles and grew to the Planetary size. Such as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. These planets and the Asteroid belt between Mars and Jupiter to the solar system originated some 4.6 billion years ago. The Earth consisted of a solid phase, the lithosphere and a gaseous envelope surrounding it, the atmosphere. The liquid phase, the hydrosphere, appeared later when the Earth cooled down to a temperature below 100′ C.
Have we ever given a thought on why there are various organisms that simply differ by very few characteristics? We might have seen the spiders in our house, a few of them are thin while there are a few others that are large with feathered legs. Similarly, the birds that swim in the water have the webbed limbs while those that fly in the sky have wings and simple clawed limbs. These might sound extremely simple to us at the time, but years ago, they were the most noted differences that not many people had noted in the earlier times. Hence going through these variations in the times when not many people were aware about evolution and science, the theory of Evolution was given by Charles Darwin.
Every single organism on earth is made from the complex structures of various cell structures that altogether combine to form the various types of tissues and organs. Thus, we can say that all organisms are basically cellular organisms.
Cells are the most important part of our life. They are known to be the structural as well as the functional unit of life and so are the most essential units in our body without which our existence is not possible.
Cell biology, in the academic discipline is the study of cells which is also known as Cellular biology, or Cytology. The study of Cell biology includes the various topics such as
The word cell is derived from the Greek word, “Kytos” meaning “container”. It encloses inside its membrane all the cell organelles which play a very vital role in all the essential life processes occurring inside our body. Thus, cell biology, along with the study of the cell structure also entails the study of all the cell organelles with their functions and the vital roles in the life processes. It also includes the study of the various cell activities that are performed inside these cells and have a great influence on our health, body and life. These activities include the cell interactions, cell signaling, life cycle, cell division (mitosis and meiosis) and finally cell death. The study of all these activities and interactions is extremely important as a minor change in them can result into a notable change in our body. Thus, it gets very essential that we learn in details about their structure and the proper working in our body.
This very basic study of the most basic unit of our life is thus categorized into the various categories based on the type of cells, their similarities and the varied differences. Simply based on the study of the cell and the cellular activities which are included in cellular biology, other fields are also developed which are:
• Genetics
• Biochemistry
• Molecular biology
• Developmental biology
These fields have their basics in cell biology, but simply spread boundlessly due to their complexity and significance. Genetics, deals with the study of the genes and the genetic codes which are the inheritable matters in our body which are transmitted from generation to the next. Biochemistry is the study of the chemical processes that occur between the various cell products that have an influence on the working of the entire body. Molecular biology is similarly the study of biology that is performed in the molecular level of all the components. And finally the developmental biology is the basic study of the major processes occurring in our body that lead to the growth and the development of a new organism. But, to learn about any of these fields, you have to learn more about the basic, that is cell biology.
Many a times, when we see the beautiful things created by the nature around us, we force ourselves to think on how they came into existence. We all know the various theories that explain the existence of our planet earth and so on for the existence of all the smallest as well as the largest creations on the planet. A small particle of dust, itself has various small entities which altogether combine to form the particle. Thus, every particle itself is a combination of biology, chemistry and physics which together work to create the particle.
Structural biology, as the name suggests is a branch of that is also a part of biochemistry and biophysics. It is concerned with the study of the minute biological molecules that altogether form a larger functional base. For instance, we know that proteins are made from the combination of various amino acids which are further made from smaller elements like carbon, nitrogen, oxygen, hydrogen and sulphur. Thus, the structural biology deals largely with the in depth study of macromolecules, about their functioning and their importance in our life.
Structural biology is the study of macromolecules that are made from various organic molecules such as the proteins, carbohydrates, lipids, and the nucleic acids. These organic molecules are the monomers that combine together through the various chemical reactions to form the polymer of these monomers that are known as the macromolecules. The macromolecules play a very important part in our existence and thus need to be studied in depth. The study if structural biology includes the thorough study of the macromolecules those are responsible for the functioning of the cells that further give rise to the proper and the smooth functioning of our body organs. These macromolecules get coiled to form a three dimensional structure which we study as the protein structural biology and due to this structure of the macromolecules, they are able to function smoothly without having any mistakes or errors that could give a possible rise to mutations. The tertiary structure of a molecule largely depends on its basic structure that is called as the primary structure. Thus, to understand the functioning of any macromolecule it most primarily gets important to study the various structures of the molecules. The equipments like the advanced light microscopes along with the methods like the NMR, Electron microscopy, crystallography, etc. help the interested biologists to study the structure of all the macromolecules properly.
In this study of the structures of macromolecules and their other possible structures, bioinformatics proves to be a boon. Bioinformatics helps the biologists to study the various patterns and their probable structures for the different sequences which proves to be very beneficial to the various biologists. Thus, through structural biology you can now study the integral membrane proteins and their shapes to have a better understanding of the structure and the functioning of these macromolecules.