2.1 Discovery Of Cell And Cell Theory

2.1 Discovery Of Cell And Cell Theory
In early classes we have studied that all living organisms are composed of cells. The question arises here how did biologist come to know that, obviously through observations. These observations started with the discovery of magnifying glasses and later on with the development of microscope. (Latin word micro = small; skopion = to see). In 1610 Galileo, an Italian astronomer and physicist developed microscope to observe small organisms. In 1665, Robert Hook made an improved microscope by combining lenses, called compound microscope and examined a slice of cork under it. He found small honey comb like chambers, which reminded him small rooms of monastery and are said cellula in Italian, so he also named these structures as cellulae or cell (small rooms). The cork was made from bark of oak, so he actually saw the cell-wall only.
in 1842, Dutrochet, boiled plant material in nitric acid and then examined under microscope. It was found to consists of cells. In 1831, Robert Brown discovered a spherical body, the nucleus in the cells of orchids. Schleiden (1838) a German botanist, proposed that all plants are made up of cells. Next year another German Zoologist, Theoder Schwann stated that all animals are made up of cells. He observed nuclei in all types of animal cells but failed to observe cell-wall in them. From here the difference between plant and animal cell started to establish. In 1858, Rudolf Virchow stated that new cells come only from other cells i.e animals cells come from animal cell and plant cells from plant cell. The combined efforts of Schleiden, Schwann and R.Virchow finally gave rise to cell theory. The salient features of the cell theory are as under:

i) All living organisms are composed of one or more cells.
ii) The cell is the smallest, basic structural and functional unit of all organisms.
iii) New cells are formed by the division of pre-existing cells.

1.8 ORIGIN OF LIFE

1.8 ORIGIN OF LIFE 1.8.1 Islamic view about the Origin of life:
The Holy Quran throws adequate light on the origin of life. The most important fact in the teachings of Quran is that Allah is the ultimate creator of every thing. Living and non-living are both created by Him. There are several verses of Quran in this regard. A few are quoted below:
"He is the Creator of the heavens and the earth".
(Surah Al'Ana'm, Ayah 102}
"That is Allah your Lord. There is no god but Him, the Creator of all things. Therefore, serve Him. He is the Guardian of all things".
(Surah Al-Ana'm, Ayah 103)
The preceding verse explains that all living beings including insects and snakes (which crawl), monkeys and grazers (four legged creatures) and birds and humans (two legged creatures) were created ultimately from water. It is stated:
"We did create man from an essence of clay".
(Surah Al-mominoon, Ayah 12)
"He (Allah) who created all things in the best way. He first created man from clay, then bred his offspring from a drop of paltry fluid. He then moulded him and breathed into him of His spirit. He gave your eyes and ears, and hearts: yet you are seldom thankful".
(Surah Al-Sajda, Ayah 7-9}
Once the life had been created, Allah implemented the process of reproduction for the continuity of races of animals. The various stages of reproduction have been described in Holy Quran in following way.
"Then fashioned we the drop a clot, then fashioned we the clot a little lump, then fashioned we the little lump bones, then clothed the bones with flesh".
(Surah Al-mominoon, Ayah 14)
"Hath there come upon man (every) any period of time in which he was a thing unremembered?"
(Surah Al-Dahar, Ayah 1)
A close study of above sermons reveals that all animals had common origin but they gradually underwent changes afterwards and became different from each other i.e. some developed crawling, some started walking on two legs and some other had four. It seemed that animals of today are advanced forms of the past animals who achieved this form after passing through many changes.
1.8.2 Concepts of Abiogenesis and Biogenesis:
Man had believed since ancient times that living organisms (both plants and animals) arise from clay, earth and other non-living matter not from pre-existing parents of their own kind. This was based on such observations as growth of fungus on pieces of bread and the appearance of maggots on dead bodies of animals. Aristotle believed that fishes, frogs and aquatic insects spontaneously developed from mud. This old belief that living beings can spontaneously develop from the non-living is termed as abiogenesis.
The idea of production of living from the non-living was experimentally analyzed. The pioneer in such experiments was an Italian scientist named Redi. Through several experiments he showed that all living organisms arise from their parents and negated the idea of abiogenesis.
The view that living beings can develop only from other living being is called biogenesis. The following are a few of the experiments which Redi performed and which led to the concept of biogenesis.
Experiment No.1
Some dead snakes were placed in a box. It was noticed that flies gathered around the dead snakes. After three days maggots appeared in their bodies. After about eighteen days these maggots transformed into pupae. Some of these pupae were then transferred to separated glass containers covered with a sheet of paper. After eight days, a fly emerged from each pupa and all flies were similar to those which visited the body of the dead snakes. From this it was concluded that maggots were the offspring’s of flies. The flies had laid eggs on the dead snakes. These eggs gave rise to maggots which formed pupae and ultimately flies emerged from them.
Experiment No.2
In another experiment Redi took eight bottles. He put dead snakes in two; pieces of meat in other bottle and dead fishes in other bottle. He kept four bottles open and four covered. After a few days, maggots appeared in the open bottles only. No maggots appeared in the bottles kept covered. This showed that if the flies were prevented from entering the bottles, the maggots did not appear.
Some workers, however, criticized this experiment and said that the maggots failed to appear in the covered bottles because air being so essential for abiogenesis could not enter these bottles. To test this, Redi performed another experiment.
Experiment No.3
Some pieces of meat were put in a bottle whose mouth was covered with a gauze. Thus, air could enter the bottle while flies remained out. Again no maggots appeared on the piece of meat, even after many days inspite of the fact that entry of air was possible.
These experiments provide evidence supporting the idea that only living beings give rise to living beings. Thus, the concept of Biogenesis is correct and that of Abiogenesis is wrong.
Needham's experiment:
In 1748, an English Scientist Needham, boiled meat in water, poured this gravy in bottles and closed their mouth with cork. After a few days many micro-organisms were produced in these covered bottles. This once again excited the believers of Abiogenesis i.e. life from non-life (Fig: 1.3).
Pasture's experiment:
The argument on the issue of biogenesis and abiogenesis continued up to the middle of nineteenth century, till Louis Pasture, a renowned French scientist proved with experiments, that abiogenesis could not occur in the present environment of earth.
In 1864, Pasture performed his experiment, in front of the commission formed of noted biologists, to resolve this issue. He took flasks which had long curved S-shaped necks (Fig. 1.4). He added fermentable infusion (yeast + sugar + water) in bottles and left their mouth open.
The yeast infusions were boiled in the flasks and let steam released out of the neck of each flask. Then flasks were allowed to cool. No life was produced even after the lapse of several days; because micro-organisms entering along with incoming air got stuck up in on the curved walls of the glass neck. To prove this he broke up the curved necks, so that now contaminated air could reach directly to the infusion. It was observed that micro-organisms were produced within 48 hours. This proved that if care was taken and no micro-organisms or their spores were allowed to reach the infusion, no life could be produced. He rejected spontaneous generation. Commission decided in favour of bio-genesis.
1.8.3 Concept of chemical and organic evolutional
The modern view of origin of life stresses upon the idea of chemical evolution and ties its origin to the history of the earth and the primitive atmosphere.
How did it happen and what evidence supports this idea?
In the beginning, the universe was an intensely hot point where matter and energy were indistinguishable. About 15 billion year ago, there was a Big Bang (huge explosion). The universe started expanding and the temperature dropped drastically. In time, about 4.6 billion years ago our earth and other planets appeared as part of the solar system. The Primitive atmosphere of the earth was rich in Hydrogen. Soon gases from the very hot and liquid core of the earth added more elements to this atmosphere. It is believed that the earth's atmosphere at this stage consisted carbon monoxide, carbon dioxide, Hydrogen, Nitrogen, water vapours and was exposed to intense radiation and electric spark. It hardly had any free oxygen. With the passage of time, the atmospheric temperature gradually dropped. This allowed condensation and heavy rains which caused formation of oceans. Thunder and lightning sparks together with ultraviolet radiation caused reactions of the atmospheric gases. This led to formation of simple organic molecules. These molecules I came down with rain and accumulated in the oceans, lakes, rivers and the soil over a very long period of time. These molecules had enough chances to interact in this environment and produce amino acids and proteins which are the building blocks of life. This sequence of chemical evolution was demonstrated in the middle of the 20th century by some clever laboratory experiments. Scientists were able to produce amino acids and simple sugars from a mixture of methane, ammonia, hydrogen and water by exposing it to electric sparks. More recent experiments using electric sparks in laboratory chambers have successfully produced not only amino acids and sugar but also the basic ingredients of fatty substances and DNA, all of which are the constituents of life.

Life originated on earth more than 3.5 billion years ago. We do not know how life formed, although the evidence is consistent with the hypothesis that it evolved spontaneously from chemicals. There is considerable discussion among biologists about what the early stages of such an evolutionary process might have been like.

What was the first life form like? The first life form, perhaps, was a sphere of naked protein or RNA and was capable of making its copies (reproduction). At some stage, a membrane assembled around the sphere giving rise to the first cell. There is now general agreement that this first life form respired anaerobically because the earth's atmosphere lacked free oxygen; it reproduced asexually. Our present day knowledge of viruses, bacteria and how DNA makes its copies provide enough hints in support of the above view. The first living organism may have been like viruses.
The next step in this story was appearance of an autotrophic way of life, that is, an organism capable of photosynthesis, adding free oxygen into the atmosphere. This availability of free oxygen opened the way for an explosion of a variety of organisms in times to come. Further improvement became possible as some of the organisms achieved the capability, to reproduce sexually.

For at least the first 2 billion years of life on earth, all organisms were bacteria. About 1.5 billion years ago, the first eukaryotes appeared.
The story of origin of life highlights change in matter. First inorganic molecules interacted in a way that organic molecules came into existence. The latter formed aggregates capable of making their copies and existed as naked spheres of protein or nucleic acids (RNA or DNA). Ultimately there arose the first cell a unit with a membrane. This tells us that life eventually arose by a slow process of chemical changes or organic evolution. The basic underlying concept in this process is that over a period of time (a very long period) one form gave rise to another. The idea of organic evolution was supported by scientist like Lamarck and Charles Darwin. They argued that new forms of life must have arisen from older ones through variations and that it was something in the process of heredity which was responsible for variations.

 

1.7 IMPACT OP BIOLOGICAL STUDIES ON HUMAN WELFARE

1.7 IMPACT OP BIOLOGICAL STUDIES ON HUMAN WELFARE
Biology has made an enormous impact on human welfare by improving quality of life. It also helped in increasing food production and to improve health. New discoveries in the field of biology are bringing revolution in medicine, public health, agriculture, dentistry, veterinary medicine, animal husbandry, land-scape, horticulture, pest control and other related fields.
1.7.1 Production of food:
Production of various kind of food especially crops like wheat, maize, rice and barely is very active field of biology. Man grew different vegetables and fruits to supplement his diet. With the advancement of biological techniques man has not only improved the quality and yield of the existing varieties but also produced many new varieties of crops. These successes have been achieved due to biological researches in the fields of pest control, genetics and biotechnology. Man also improved the quality and quantity of food products by developing dairy farming, poultry farming, kettle farming etc, and wheat, rice, maize and other plants. This helped to overcome the problem of food shortage. Incidence of famine has declined and economic conditions for mankind have improved.
1.7.2 Improvement of health:
In the field of health, the discovery and development of new medicines, vaccines and diagnostic medical equipment has been very helpful to man kind. This is only possible due to research in biology. The discovery and development of antibiotics by biologist has played a vital role in improving our general health conditions. Many fatal and epidemic diseases such as smallpox, tetanus, diphtheria etc. can be easily controlled because of" development of vaccines against these diseases. This has resulted in a great reduction in infant mortality. Every day new drugs are constantly being developed by biologists to fight against the pathogenic organism enabling to solve the health problems of mankind.
1.7.3 Improvement of environment:
During the past few decades, rapid industrialization has resulted in pollution of surroundings including air, land and water sources. As a result of this pollution not only human beings but also animal and plant life is exposed to all kinds of harmful effects. It is through biological research that we are finding out ways and means to overcome and at last eliminate the pollutants, for providing and maintaining healthy environment.
1.7.4 Genetic engineering:
A new methodology referred to as recombinant DNA technology or genetic engineering has been developed. It is technique in which alteration of gene, DNA of an organism is carried out to seek benefit for mankind. It provides a way by which mammalian proteins can be produced in bacterial cells. Genes controlling the synthesis of important drugs and hormones can be taken from the organisms in which they occur naturally and placed in bacterium or other type of organism, from which the product can be recovered conveniently and in large quantities. Most noteworthy achievement is insulin production by adding human gene in bacterial DNA which is helping to produce human insulin (Humalin) from bacteria on commercial basis. This is very useful for treating diabetes. This is one example along with many others like cloning, tissue culture etc, where genetic engineering is being used.
Many inheritable diseases can now be diagnosed in a developing child before birth. Recent research has led to the hope that cystic fibrosis (hereditary disease of human being in which affected individual secrete thick mucus that clogs the air ways of lungs / liver / pancreas) and other hereditary disease will soon be treatable.

Although there are many side effects of these technologies yet no one of us wishes to go back to the days in which large number of people died of epidemic diseases. As science has conquered one disease after another, the world's death rate has fallen and the human population has exploded. Few of us are willing to give up technology's gift of private automobile, though we are concerned about the amount of air pollution that automobile generate.

1.6 HISTORY OF BIOLOGY

1.6 HISTORY OF BIOLOGY
The history of biology goes back to the ancient and pre historic time. Very briefly, perhaps the first noticeable development in our knowledge of biology occurred during the Greek period. Individual like Aristotle (322-384 B.C) is remembered even today. He wrote a book "Historia Animalia". Carolus Linnaeus founder of biological classification, classified animals into two units i.e. genus and species. The Phrastus, discovered sex in plants and described about five hundred plants therefore, known as founder of Botany. Hardly any original addition to biological knowledge was made by the Romans, who followed the Greeks. It was not until the beginning of the Muslim period, nearly a thousand years later that revolutionary developments occurred not only in biology but in the science in general.
From the 8th to the 15th century, Muslims studied Greek and other literature, translated books of Roman and Sanskrit into Arabic, wrote new books and opened numerous centers of learning which encouraged original research and exchange of ideas between different human societies. The most outstanding contribution of Muslim scientists had been the use of experiments for the first time in scientific study. This period was truly a period of progress in biology and medicine. The following is a modest list of contributions by the Muslim and other scientists between the 8th and 20th century.
Muslim and other Biologists:
Muslims have made important contributions in the field of biology in earlier ages.
Jabir-Bin-Hayan (722-817 A.D), wrote books named "Al-Nabatat" and "Al-Haywan" on plants and animals respectively.
Abdul Malik Asmai (741 A.D), wrote books "Alkheil, Al-IbiL "Al-wahoosh", "As-Sha" and "khalaqul Insan", describing structure and function of body parts of horses, camels, sheep, wild animals and human being. "Khalaqul Insan" was popular among the western experts in Zoology. He was regarded a specialist of his time.
Ali bin Rabban Tubri (775-870 A.D), wrote book "Firdus-ul-Hikma" having many illustrations and detailed articles on Philosophy, Zoology, Psychology and Astronomy.
Abu-Usman Umer Aljahiz, wrote book "Al-Haywan" which described characteristics of 350 species of animals especially, about life of ants.
Al-Farabi (870-950 A.D) and Abul-Qasim Al-Zahravi (936-1004 A.D). Both were the renowned hakim and surgeon of the Islamic World. Al Farabi is the author of two very well known books i.e. "Kitab-i-Nabatat" and "Kitab-ul-Haywanat" and Zahravi was famous for the removal of urinary bladder stone.
Ibn-al Haitham (965-1039 A.D), wrote books like "Kitabul Manazir" and "Mizanul-Hikma", He explained the phenomenon of vision and corrected the Greek conception about vision.
Bu-Ali Sina (980 A.D), wrote books "Al-Qanoon" and "Fil Tib Al-Shifa", about plants, animals and non-living things. He is considered as one of the founder of medicine, acknowledged by the greatest expert of his time in medicines in east and west.
Ziauddin Ibn-Baitar (13th century A.D) specialized in the study of plants. He travelled to several countries, observed and studied many species of plants.
Ibn-al Nafees (13th century A.D) described the process of blood circulation in human body.
Kamal-ud-Din al-Damiri (14th century A.D) compiled a book "Hayat-al-Haywan" deals with the characteristics of 1000 kinds of animals.
Ali bin Isa was a well known eye-specialist of his time and worked on structure, function and the diseases of the eye. He wrote three volumes on this subject in which he described 130 diseases of the eye.
Abul Qasim Majreeti is especially known in Europe for his book on animal species.
Other Biologists:
After 15th century, European and other biologists made important contribution in the field of Biology.
William Harvey (1578-1657 A.D), described circulation of blood.
Galileo (1610) invented microscope to examine small organisms.
Robbert Hook (1665) discovered "cell" the basic unit of living organism.
Linnaeus (1707-1778 A.D), developed methods of classification for organisms and gave nomenclature and therefore, called father of taxonomy.
Schleiden and Schawann (1839), worked on the detailed structures of plant and animal cell, finally formulated cell theory.
Louis Pasteur (1822-1895) discovered bacteria as causes of many diseases like Tuberculosis.
J.Lister (1860), discovered antiseptics e.g. Iodine and carbolic acid.
E. Jennar (1896), discovered method of vaccination against small pox.
Charles Darwin (1859), wrote his famous book "origin of species" about evolution of different species through Natural selection.
Gregor John Mendal (1822-1884) gave his famous laws of heredity and laid foundation of Genetics.
Watson and Crick (1953) proposed double helix model of DNA to explain the function of DNA as heredity material.

1.5 BIOLOGICAL METHOD

1.5 BIOLOGICAL METHOD
A biological method is a scientific approach used to resolve a biological problem related to or produced by a living organism. In order to resolve a specific biological problem a biological method is adopted, which consists of following steps.
(i) Observation (ii) Hypothesis (iii) Deduction
(iv) Experiment (v) Result (vi) Law or theory
1. Observation:
Most of the biological investigations start with an observation. After selecting, specific biological problem, observations are made to collect relevant information. For example; take the case of malaria. Malaria is a the greatest killer disease of man for centuries. Malaria was the one among many other diseases for which a cure was needed.
In 1878, a French physician, Laveran, studied the blood sample of malaria patient under microscope and observed tiny creatures in it. These creatures were later named Plasmodium.
2. Hypothesis:
In the light of observed facts and previously collected information (data) biologists make 'intelligent guesses' as to what may be the possible answer to this particular question. This intelligent guess in a form of a statement is called hypothesis. So, the hypothesis is a statement made by scientists about a certain phenomenon, on the basis of available information. For example, an observation was made that Plasmodium is present in the blood of malaria patients. So a question was raised, is Plasmodium the cause of malaria? It would be a good guess to say 'yes' but it is only a guess which can be presented as a hypothesis that:
"Plasmodium is the cause of malaria”.
3. Deduction:
To test the hypothesis certain deductions that are logical prediction are made. In other words deduction is the logical explanation of a hypothesis. It does not require any type of experimentation. For example, to test the above hypothesis the following deductions were made.
"If Plasmodium is the cause of malaria, then all the patient suffering from malaria should have malarial parasite in their blood while healthy people should not have".
A number of deductions can be made to explain the hypothesis. These deductions can be tested and verified by experiments.
4. Experiment:
The next step is to test each deduction (prediction) practically to find out whether or not the hypothesis is correct. In testing the deduction we are actually testing a hypothesis. This is where the scientist shows his skill as an experimenter. For this purpose, scientist performs two types of test i.e. control and experimental groups. Control group means a group of healthy people and experimental group means group of malaria patients. Both groups were kept in identical conditions. In order to find out the real cause of malarial, scientists examined the blood of about 100 malaria patients and also examined the blood of 100 healthy persons.
5. Result:
From above experiment it was found that all the malarial patients had Plasmodium in their blood, where as the blood of healthy persons were free from Plasmodium. These results verified the deduction and finally the hypothesis i.e. "Plasmodium is the cause of malaria".
6. Theory:
It is not always possible to confirm a hypothesis immediately. The validity of a hypothesis rests on a gradual accumulation of indirect evidences. As more and more evidence come to hand, the hypothesis gain increasing acceptance and eventually is promoted to the rank of a theory: A theory is a set of scientific assumptions consistent with one another and supported by evidence, but not fully proved e.g. theory of evolution
Thus a biologist studies a problem in a sequential manner through observations, questions, hypothesis, deduction, testing or experimentation. A set of data taken from experiment, proves or disproves the hypothesis. A cautious attitude expressed in the form of criticism and further tests are performed until a satisfactory answer is obtained.

The results of observations and experiments are published in scientific journals or presented in conferences, where they can be examined by all. These results must be repeatable that is they should be obtained by any one doing the same procedure.

1.4 BIOLOGY AND OTHER SCIENCES

1.4 BIOLOGY AND OTHER SCIENCES
Biology is a multi dimensional science. It is linked with the knowledge of chemistry, physics, mathematics, sociology, statistics etc. and these branches which are related to biology are biochemistry, biophysics, biometry, etc. Some of them are discussed below.
1. Biochemistry: A complete branch of chemistry which requires firm knowledge of biology and chemistry to explain the synthesis of bio-molecules, their requirement and the effect caused by the deficiency and efficiency of different molecules on the organisms and their metabolism.
2. Biophysics: Branch of physics where we apply laws and techniques of physics to explain the metabolism of living organism, to find out the age of fossils etc. One of the sub-branch of biophysics is Radio-physics, where radioactive isotopes are used to trace the translocation of different material "in vivo", that is, within the living organism. Radio labeling and carbon dating also show some uses of radio active isotopes in determining the age of fossils. Use of sound waves as ultrasound and laser technology show some relationship of physics with biology.
3. Biometry: It is branch of mathematics where data and measurements related to living organisms are dealt with. Without knowledge of mathematics and statistics no biological research and data analysis is possible. All biologists conclude their results by using knowledge of statistics and mathematics.
4. Behaviourial biology: Many of the facts of biology are reflected in the study of behaviour it is an intersection of biochemistry, genetics, physiology, evolutionary theory and ecology.
5. Biosociology: The study of behaviour, especially social behaviour, also associates biology to the social sciences and humanities. Through the study of life in general, we will learn more about ourselves.
Finally, we can say that biology is related with each branch of science.

1.3 BRANCHES OF BIOLOGY

1.3 BRANCHES OF BIOLOGY
Nearly two million species (kinds-types) of plants and animals are known to the world. Modern biology does not concern only with the recognition and classification of these species but also deals with their structural and functional aspects. Extensive research during the 20 century has led to the division of biology into a large number of specialized branches. Some of the important branches of biology common to botany and zoology are:
i) Morphology (Gr: Morphe = form): This branch deals with the study of external structural characteristics of plants and animals.
ii) Anatomy (Gr: Ana = up, tome = to cut): It deals with the internal structures or organs of an organism. In plants it deals with the arrangement of different types of tissues in root, stem leaf etc.
iii) Histology: (Gr: Histos = web or tissues): It deals with the study of tissues of plants and animals under a microscope.
iv) Cytology or Cell-Biology (Gr: Kytos = hollow vessel or cell): The study of structure, function and composition of cell and cell organelles is called cytology or cell-biology.
v) Physiology (Gr: Phusis = nature): It is the study of functions of different parts of living organisms.
vi) Ecology (Gr: Oikos = home): It is the study of relationships of living organisms with each other and with their non-living environment. It is also called environmental biology.
vii) Embryology (Gr: Embryon = embryo) or developmental biology: It is the study of progressive developmental changes which occur after zygote formation upto an organism is formed.
viii) Taxonomy (Gr: Taxis = arrangement or grouping; Noms = laws related to naming): It deals with the description; identification, classification and scientific naming of living organisms, according to their similarities and dissimilarities.
ix) Genetics (Gr: Genesis = origin): It deals with the study of inheritance including transmission of hereditary characters from parents to their offspring.
x) Palaeontology (Gr: Palaios = ancient, ontos = being organisms): It is the study of animals and plants that lived in the remote past and are now found as fossils in the rocks. It can be further divided into two branches i.e. Palaeobotany; study of plant fossils, Palaeozoology, study of animal fossils.

In the ancient past large quantities of dead organisms were fossilized and formed coal, oil and other fossil fuel.

xi) Biochemistry: It deals with the chemistry and chemical aspects of the living system.
xii) Microbiology (Micro = very small): It deals with the study of microscopic organisms such as viruses, bacteria, etc.
xiii) Biotechnology: It is the manipulation of living things (animals, plants, micro-organism) for the welfare of mankind. Recently methods of genetic engineering have brought about a revolution in this field. By using these techniques not only yoghurt, cheese, bread, insulin, antibiotics etc. Are being produced but number of diseases are cured.