Biology

DNA sequencing is the driving force behind key discoveries in medicine and biology. For instance, the complete sequence of an individual's genome provides important markers and guidelines for medical diagnostics and healthcare. Up to now, the major roadblock has been the cost and speed of obtaining highly accurate DNA sequences. While numerous advances have been made in the last 10 years, most current high-throughput sequencing instruments depend on optical techniques for the detection of the four building blocks of DNA: A, C, G and T. To further advance the measurement capability, electronic DNA sequencing of an ensemble of DNA templates has also been developed.

Most people are fascinated by the colorful and exotic coral reefs, which form habitats with probably the largest biodiversity. But human civilization is the top danger to these fragile ecosystems through climate change, oxygen depletion and ocean acidification. Industrialization, deforestation and intensive farming in coastal areas are changing dramatically the conditions for life in the oceans. Now scientists at the Max Planck Institute for Marine Microbiology from Bremen together with their colleagues from Australia, Sultanate of Oman and Italy have investigated how and why the corals die when exposed to sedimentation. According to their findings, oxygen depletion, together with an acidification of the environment, creates a chain reaction that leads to coral death.

Naked mole-rats evolved to thrive in an acidic environment that other mammals, including humans, would find intolerable. Researchers at the University of Illinois at Chicago report new findings as to how these rodents have adapted to this environment.

For nearly 260 years -- since Carl Linnaeus developed his system of naming plants and animals -- researchers classified species based on visual attributes like color, shape and size. In the past few decades, researchers found that sequencing DNA can more accurately identify species. A group of single-celled algae -- Symbiodinium -- that live inside corals and are critical to their survival -- are only now being separated into species using DNA analysis, according to biologists. "Unfortunately with Symbiodinium , scientists have been hindered by a traditional morphology-based system of species identification that doesn't work because these organisms all pretty much look the same -- small round brown cells," said Todd LaJeunesse, assistant professor of biology at Penn State. "This delay in adopting the more accurate convention of identifying species using genetic techniques has greatly impeded progress in the research of symbiotic reef-building corals, especially ...

 Melbourne researchers have identified a new way of protecting female fertility, offering hope to women whose fertility may be compromised by the side-effects of cancer therapy or by premature menopause. The researchers, from the Walter and Eliza Hall Institute, Monash University and Prince Henry's Institute of Medical Research, made the discovery while investigating how egg cells die. They found that two specific proteins, called PUMA and NOXA, cause the death of egg cells in the ovaries. The finding may lead to new strategies that protect women's fertility by blocking the activity of these two proteins. Associate Professor Clare Scott from the Walter and Eliza Hall Institute said the research showed that when the DNA of egg cells is damaged following exposure to radiation or chemotherapy, such as that received during some cancer treatments, PUMA and NOXA trigger the death of the damaged eggs. This egg cell death causes many female cancer patients to become infertile. ...

The endocrine glands and hormone producing diffused tissues/cells located in different parts of our body constitute the endocrine system. Pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads (testis in males and ovary in females) are the organised endocrine bodies in our body (Figure 22.1). In addition to these, some other organs, e.g., gastrointestinal tract, liver, kidney, heart also produce hormones. A brief account of the structure and functions of all major endocrine glands and hypothalamus of the human body is given in the following  sections.

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types – alternate, opposite and whorled . In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sun flower plants. In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia.

This is the largest phylum of Animalia which includes insects. Over two-thirds of all named species on earth are arthropods (Figure 4.12). They have organ-system level of organisation. They are bilaterally symmetrical, triploblastic, segmented and coelomate animals. The body of arthropods is covered by chitinous exoskeleton. The body consists of head, thorax and abdomen. They have jointed appendages (arthros-joint, poda-appendages). Respiratory organs are gills, book gills, book lungs or tracheal system. Circulatory system is of open type. Sensory organs like antennae, eyes (compound and simple), statocysts or balance organs are present. Excretion takes place through malpighian tubules. They are mostly dioecious. Fertilisation is usually internal. They are mostly oviparous. Development may be direct or indirect. Examples: Economically important insects – Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect) Vectors – Anopheles, Culex and Aedes (Mosquitoes)...

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Presence or absence of a cavity between the body wall and the gut wall is very important in classification. The body cavity, which is lined by mesoderm is called coelom. Animals possessing coelom are called coelomates, e.g., annelids, molluscs, arthropods, echinoderms, hemichordates and chordates (Figure 4.3a). In some animals, the body cavity is not lined by mesoderm, instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and the animals possessing them are called pseudocoelomates, e.g., aschelminthes (Figure 4.3b). The animals in which the body cavity is absent are called acoelomates

Animals can be categorised on the basis of theirsymmetry. Sponges are mostly asymmetrical,i.e., any plane that passes through the centredoes not divide them into equal halves. Whenany plane passing through the central axis ofthe body divides the organism into two identicalhalves, it is  called radial symmetry .Coelenterates, ctenophores and echinoderms have this kind of body plan Animals like annelids, arthropods, etc., where the body can be divided into identical left and right halves in only one plane, exhibit bilateral symmetry

Rhodophyta are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body. Majority of the red algae are marine with greater concentrations found in the warmer areas. They occur in both well-lighted regions close to the surface of water and also at great depths in oceans where relatively little light penetrates. The red thalli of most of the red algae are multicellular. Some of them have complex body organisation. The food is stored as floridean starch which is very similar to amylopectin and glycogen in structure. The red algae usually reproduce vegetatively by fragmentation. They reproduce asexually by non-motile spores and sexually by non-motilegametes. Sexual reproduction is oogamous and accompanied by complex  post fertilisation developments. The common members are: Polysiphonia, Porphyra , Gracilaria and Gelidium.

These organisms are mostly marine and photosynthetic. They appear yellow, green, brown, blue or red depending on the main pigments present in their cells. The cell wall has stiff cellulose plates on the outer surface. Most of them have two flagella; one lies longitudinally and the other transversely in a furrow between the wall plates. Very often, red dianoflagellates (Example: Gonyaulax) undergo such rapid multiplication that they make the sea appear red (red tides). Toxins released by such large numbers may even kill other marine animals such as fishes.

These bacteria are special since they live in some of the most harsh habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens). Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions. Methanogens are present in the guts of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.

Taxonomic studies consider a group of individual organisms with fundamental similarities as a species. One should be able to distinguish one species from the other closely related species based on the distinct morphological differences. Let us consider Mangifera indica, Solanum tuberosum (potato) and Panthera leo (lion). All the three names, indica, tuberosum and leo, represent the specific epithets, while the first words Mangifera, Solanum and Panthera are genera and represents another higher level of taxon or category. Each genus may have one or more than one specific epithets representing different organisms, but having morphological similarities. For example, Panthera has another specific epithet called tigris and Solanum includes species like nigrum and melongena. Human beings belong to the species sapiens which is grouped in genus Homo. The scientific name thus, for human being, is written as Homo sapiens.

Following this synthesis of ideas, experimental verification of the chromosomal theory of inheritance by Thomas Hunt Morganand his colleagues, led to discovering the basis for the variationthat sexual reproduction produced. Morgan worked with the tiny fruit files ,Drosophila melanogaster   which werefound very suitable for such studies. They could be grown onsimple synthetic medium in the laboratory. They complete their lifecycle in about two weeks, and a single mating could produce a largenumber of progeny flies. Also, there was a clear differentiation of thesexes – the male and female flies are easily distinguisable. Also, it has many types of hereditary variations that can be seen with low power microscopes.

Mutation is a phenomenon which results in alteration of DNA sequencesand consequently results in changes in the genotype and the phenotypeof an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA. One DNA helix runs continuously fromone end to the other in each chromatid, in a highly supercoiled form. Therefore loss (deletions) or gain (insertion/duplication) of a segment of DNA, result in alteration in chromosomes. Since genes are known to belocated on chromosomes, alteration in chromosomes results inabnormalities or aberrations. Chromosomal aberrations are commonly observed in cancer cells.In addition to the above, mutation also arise due to change in a single base pair of DNA. This is known as point mutation. A classical example of such a mutation is sickle cell anemia. Deletions and insertions of basepairs of DNA, causes frame-shift mutations (see Chapter 6). The mechanism of mutation is beyond the scope of this discussion, at this...

This sex linked recessive disease, which shows itstransmission from unaffected carrier female to some of the male progeny has been widely studied. In this disease, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected. Due tothis, in an affected individual a simple cut will result in non-stop bleeding. The heterozygous female (carrier) for haemophilia may transmit the diseaseto sons. The possibility of a female becoming a haemophilic is extremely rare because mother of such a female has to be at least carrier and thefather should be haemophilic (unviable in the later stage of life). The family pedigree of Queen Victoria shows a number of haemophilic descendentsas she was a carrier of the disease.

There Major Syndromes Found in Human Being 1. Down Syndrome The cause of this geneticdisorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21). This disorder was first described by LangdonDown (1866). The affected individual is short statured with small round head, furrowedtongue and partially open mouth (Figure 5.16).Palm is broad with characteristic palm crease.Physical, psychomotor and mental development is retarded 2. klinefelter's Syndrome This geneticdisorder is also caused due to the presence of an additional copy of X-chromosome resultinginto a karyotype of 47, XXY. Such anindividual has overall masculine development , however, the feminine development (development of breast, i.e., Gynaecomastia)is also expressed (Figure 5.17 a). Suchindividuals are sterile 3. Turner's Syndrome Such a disorder iscaused due to the absence of one of the X chromosomes, i.e., 45 with X0, Such femalesare sterile as ovaries are rudimentary besid...

While proposing the double helical structure for DNA, Watson and Crick had immediately proposed a schemefor replication of DNA. To quote their original statement that is as follows:‘‘ It has not escaped our notice that the specificpairing we have postulated immediately suggests a possible copying mechanism for the genetic material’’(Watson and Crick, 1953) . The scheme suggested that the two strands wouldseparate and act as a template for the synthesis of new complementary strands. After the completion of replication, each DNA molecule would have oneparental and one newly synthesised strand. Thisscheme was termed as semiconservative  DNA

The salient features of genetic code (i)The codon is triplet. 61 codons code for amino acids and 3 codons donot code for any amino acids, hence they function as stop codons. (ii)One codon codes for only one amino acid, hence, it is unambiguous and specific (iii)Some amino acids are coded by more than one codon, hencethe code is. degenerate (iv)The codon is read in mRNA in a contiguous fashion. There areno punctuations. (v)The code is nearly universal:for example, from bacteria to human UUU would code for Phenylalanine (phe). Some exceptions to thisrule have been found in mitochondrial codons, and in someprotozoans. (vi)AUG has dual functions. It codes for Methionine (met) , and it also act as initiator codon

Some of the salient observations drawn from human genome project areas follows: (i)The human genome contains 3164.7 million nucleotide bases. (ii)The average gene consists of 3000 bases, but sizes vary greatly, withthe largest known human gene being dystrophin at 2.4 million bases. (iii)The total number of genes is estimated at 30,000–much lower than previous estimates of 80,000 to 1,40,000 genes. Almost all(99.9 per cent) nucleotide bases are exactly the same in all people. (iv)The functions are unknown for over 50 per cent of discovered genes. (v)Less than 2 per cent of the genome codes for proteins. (vi)Repeated sequences make up very large portion of the humangenome. (vii)Repetitive sequences are stretches of DNA sequences that arerepeated many times, sometimes hundred to thousand times. They are thought to have no direct coding functions, but they shed light on chromosome structure, dynamics and evolution. (viii)Chromosome 1 has most genes (2968), and the Y has t...

Eocene and Oligocene: early equids Hyracotherium Orohippus  Epihippus  Mesohippus  Miohippus Miocene and Pliocene: true equines  Kalobatippus  Parahippus  Merychippus  Hipparion  Pliohippus  Dinohippus  Plesippus  Modern horses  Equus  Pleistocene extinctions  Return to the Americas Toes The ancestors of the horse came to walk only on the end of the third toe and both side toes. Skeletal remnants show obvious wear on the back of both sides of metacarpal and metatarsal bones, commonly called the “splint bones”. They are the remnants of the second and the fourth toe. Modern horses retain the splint bones; they are often believed to be useless attachments, but they in fact play an important role in supporting the carpal joints (front knees) and even the tarsal joints (hocks). Teeth Throughout the phylogenetic development, the teeth of the horse underwent significant changes. The type of t...

To avoid Unwanted disease / infection one should follow the simple principal :- 1. Avoid sex with unknown partners/multipule partners. 2.Always use condoms during coitus. 3.In case of doubt, go to a qualified doctor for early detection and get complete treatment if diagnosed with disease.

The major uncurable diseases are :- 1. Hepatitis -B 2. Genital Herpes 3. HIV infection

A larger no. of couples all over world including india are infertile i.e. they are unable to produce children inspite of unprotected sexual co-habitation.  Reasons For infertility  1. Physical  2. congenital  3. Diseases 4.Use of Drugs  5. Immunological

Some species of Asteraceae and grasses Have a evolved special mechanism to produse seeds withou fertilisation called apomixis 

Some Fruits are develop without fertilization.those type of fruits are called Parthenocarpic fruits  Example :- Banana 

If the female flower is bisexual , removal of anthers from the flower bud before the anther dehisce using a pair of forceps this is called emasculation . Emasculated flowers have to be covered with a bag of suitable size made of butter paper to prevent contamination of its stigma with unwanted pollen . this process is called bagging 

Growing of plants in different places is done by the process called pollination in this process:- Transfer of pollen grains to the stigma of a pistil is called Pollination.  This process can be achieve by external agents such as wind , animal etc

Embryogenesis refers to the process of development of embryo from the zygote. During embryogenesis ,zygote undergoes cell division and cell differentiation.

The total no. of chromosomes in one organisms body is 46. so to maintain that no. the produced sperm or ova in male and female body resp. are haploid so while the fusion take palce it can be again be 46. Haploid No:- 23 in both sperm and ova Diplaoid (when fused):-46

Gametogenesis refers to the process of formation of two types of gamets :- male and female (sperm and ova) The formed gametes are haploid in number i.e. n.

A botanical garden (or botanic garden) is a well-tended area displaying a wide range of plants labelled with their botanical names. It may contain specialist plant collections such as cacti and succulent plants, herb gardens, plants from particular parts of the world, and so on; there may be greenhouses, shadehouses, again with special collections such as tropical plants, alpine plants or other exotic plants. Visitor services at a botanical garden might include tours, educational displays, art exhibitions, book rooms, open-air theatrical and musical performances and other entertainment. Botanical gardens are often run by universities or other scientific research organizations and often have associated herbaria and research programmes in plant taxonomy or some other aspect of botanical science. In principle their role is to maintain documented collections of living plants for the purposes of scientific research, conservation, display and education, although this will depend on ...

Escherichia coli Monera  is a kingdom that contains unicellular organisms without a nucleus (i.e., a prokaryotic cell organization), such as bacteria . The kingdom is considered superseded.The taxon Monera was first proposed as a phylum by Ernst Haeckel in 1866. Subsequently, the taxon was raised to the rank of kingdom in 1925 by Édouard Chatton. The last commonly accepted mega-classification with the taxon Monera was the five-kingdom classification system established by Robert Whittaker in 1969. Under the three-domain system of taxonomy, which was established in 1990 and reflects the evolutionary history of life as currently understood, the organisms found in kingdom Monera have been divided into two domains, Archaea and Bacteria (with Eukarya as the third domain). Furthermore the taxon Monera is paraphyletic. The term "moneran" is the informal name of members of this group and is still sometimes used (as is the term "prokaryote") to denote a member of e...

R.H Whittaker in 1969 proposed a five kinddom classification. The kingdom defined by him were named Monera , Protista , Fungi, Plantae and Animalia.  The criteria for classification is cell structure , thallus orgamisation , mode if nutrition.

There are no hard and fast rules that a taxonomist has to follow in deciding what does and what does not belong in a particular genus. This does not mean that there is no common ground among taxonomists in what constitutes a "good" genus. For instance, some rules-of-thumb for delimiting a genus are outlined in Gill. According to these, a genus should fulfill three criteria to be descriptively useful: monophyly – all descendants of an ancestral taxon are grouped together; reasonable compactness – a genus should not be expanded needlessly; and distinctness – in regards of evolutionarily relevant criteria, i.e. ecology, morphology, or biogeography; note that DNA sequences are a consequence rather than a condition of diverging evolutionary lineages except in cases where they directly inhibit gene flow (e.g. postzygotic barriers).

The generic name is a component of the names of taxa of lower rank. For example, Canis lupus is the scientific name of the Gray wolf , a species, with Canis the generic name for the dog and its close relatives, and with lupus particular (specific) for the wolf (lupus is written in lower case). Similarly, Canis lupus familiaris is the scientific name for the domestic dog. Taxonomic units in higher ranks often have a name that is based on a generic name, such as the family name Canidae, which is based on Canis. However, not all names in higher ranks are necessarily based on the name of a genus: for example, Carnivora is the name for the order to which the dog belongs.

Biologist follow universal accepted principal to provide naming the organisms. Each name has two parts  1. Generic name   2. Specific epithet This system of providing a name of two component is called Binomial nomenclature 

Bio Means Life And Logy  means to understand the logic of different life forms present  in our world.