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Biology is the scientific study of life. It is a natural science that uses the methods of empirical experimentation and observational analysis to examine living processes, including growth, reproduction, variation and heredity. Biology is the most fundamental of all sciences. It is a major area of academic study in elementary and secondary schools. The principles studied by biologists include cellular respiration, photosynthesis, genetic recombination, body structure and function, physical development of organisms from fertilization to death as well as how life arises from other forms of matter. Biology covers the molecular level molecular biology studies life at this microscopic level with an emphasis on DNA genetics molecules that contain hereditary information in the form of genes which encode proteins for traits.

Biologists are also concerned with the evolutionary mechanisms of inheritance and how they differ from heredity. Biologists study the changes that occur within organisms, including aging and death, in response to their environment, often observing the existence of patterns in their changes. Some specific examples of life processes studied by biologists include:
Biology therefore deals with life processes as well as any phenomenon of life; including reproduction and genetics.

"I have been a biologist all my working life, first as an undergraduate studying physiology at Cambridge University then as a researcher at Cambridge University before moving over to Oxford in the late 1960s," Peter Campbell remembers himself saying to his wife when she asked him what he did for a living. "She laughed and asked if I meant to say that I studied living things for my living," he says. The conversation was short, but the point has stuck with Campbell.

"To a biologist, there is no such thing as inanimate matter," he writes. "Anything that exhibits properties that we would associate with life is alive, including crystals and pieces of metal, or even pieces of our own bodies."
Biology deals with the structure and function of an organism or a group of organisms. It also involves studies into their origins and interactions between them (see Ecosystem). Biology is closely related to the study of medicine correlating with the treatment and prevention of diseases.

Over the last century, biology has become an increasingly important branch of science and engineering. The demand for biology and medicine is increasing in Asia, Europe and South America and it is expected that the rates of pay offered to biologists will continue to rise.
The work of biologists (in addition to biologists there are also mathematicians, chemists, physicists) is essential in the study of life processes and cells as well as investigating DNA and molecular processes.

Biology is the scientific study of life processes in all organisms, micro-organisms and plants as well as the evolutionary relationship between these organisms. It is also known as the science that deals with living systems. Biology deals with living things, both plant and animal life and their physiology, behaviour and biological interactions with other organisms. The scientific method is fundamental to biology and involves conducting experiments, forming and testing hypotheses, constructing theories and building models.

Biology investigates the molecular level molecular biology studies life at this microscopic level with an emphasis on DNA genetics molecules that contain hereditary information in the form of genes which encode proteins for traits. It is concerned with the way living organisms grow, replicate and die. It also deals with the way that organisms interact and adapt to the environment. In terms of subject matter it encompasses a variety of fields such as evolutionary biology, developmental biology, genetics, physiology and ecology.

Biology is a major area of academic study in other school subjects. Biology is taught in schools at all levels. It is also taught at a higher level in colleges and universities as part of a Bachelor's degree or postgraduate studies, such as Master's and doctorate degrees.

"The word biology comes from the Greek word for life, βίος ," says Professor Neil Campbell, "and the suffix -λογία . The science of biology encompasses all aspects of life."
Bio systems engineering involves the application of biology and engineering to solve problems from agriculture to medicine and synthetic biology.

"We describe a bio system as a complex network of interactions involving information, energy and matter. A bio system is broadly defined in the same way as engineering systems, using a set of abstract processes and elements to define what a system is. This is similar to how we describe engineering systems but with different abstractions. The main difference is we use biological processes like electrical and chemical signals that are responsible for communication between cells to define the structure."
Bio systems engineers study networks within living organisms such as the internet on planet Earth to identify key elements and their interactions. They then use this knowledge to design man-made networked information technologies inspired by biology that work in real environments, like our bodies or in the soil.

Bio sustainable methods are a type of biological techniques or biological techniques. This is ways to preserve and increase biodiversity in the pursuit of sustainable living. It helps the individual to be able to maintain their wealth and security in the future.
Bio-economics is an interdisciplinary field of study that aims at producing economical production processes that protect the environment while maximizing economic benefits, that is incorporation of ecological processes into economic systems, these are applied as tools for solving problems, combinations of organisms and ecosystem modeling.

Biology is an interdisciplinary field of study. "It encompasses information, energy and matter." Unlike many other disciplines, its goal is not to discover something new but to explain the existing phenomena. Bio-economics or economic systems combines economics, biology and ecology as a whole.

Biochemistry refers to the study of biological compounds such as fats, proteins, carbohydrates and nucleic acids at the molecular level of biological systems. Biochemistry is a branch of chemistry that studies organic molecules and how they are formed, relate to each other and function in organisms. Thus biochemistry includes both organic chemistry and physical chemistry. The reduction reaction form of thermodynamics is included in biogeochemistry or geochemistry.

Bioinformatics is the study of recording, storage and processing of knowledge from life sciences related to molecular data processing. This process uses computers to store, retrieve and analyze information. Biotechnology is the application of genetics, microbiology and nanotechnology for the development or improvement of agriculture or other aspects of human life.

The possible functionality of microbial communities in cycling nutrients is a bio-remediation process that utilizes natural biological systems to break down a contaminant such as petroleum oil spilled into water systems by industrial accidents or defined contaminants such as pesticides, heavy metals and radio-toxic chemicals released into the environment by industry.
Biogeochemistry is the study of interactions among the elements of an ecosystem; it focuses on chemical reactions and cycles that involve living organisms.

Microbiology is the study of microorganisms, which can be single-celled microorganisms such as bacteria, or complex cells such as eukaryotic cells (cells with membrane-bound internal structures), plant cells, fungal cells and animal cells (which include human beings). Microorganisms are often essential in carrying out essential biochemical processes that can not be carried out by larger organisms. They also cause many infections in plants and animals.

Nanotechnology is a branch of engineering that deals with dimensions and tolerances of less than 100 nanometres (0.000001 m).

Zoology is the study of animals, including their classification, relationships, habits and distribution. Zoological research involves life sciences. It encompasses research on the subjects that includes animal biology, animal behavior and a special focus on zoo science. It also provides an opportunity for research biologists to have a firsthand involvement with other species besides humans.

Aquaculture involves cultivating aquatic plants or marine fish in an aquarium or in ponds or in artificial lakes. This technique is used to increase the availability of food and medicines through cultivation of organisms that can be harvested by humans.

Aquatic biology is the study of organisms that live in fresh water environments such as rivers, lakes, ponds and streams. It includes aspects of biology such as taxonomy (their identification and classification) and ecology (their relationships with their environment). It also looks at the techniques used to cultivate aquatic life in an aquarium or pond.

Coral biology is a field of study involving the science of corals. Coral reefs are made up of individual organisms called polyps that act as a single organism because they're connected by tissue. Coral reefs are found in tropical waters and give coral reef ecosystems their name.

Dinoflagellate biogeochemistry is a branch of biogeochemistry and ecology. "Biogeochemical cycles depend on the availability of nutrients and light within an ecosystem". Dinoflagellates are microscopic algae that live within a few cells and use their internal photosynthetic systems to harness energy from light. The photosynthesis process in dinoflagellates has not been studied deeply, but is believed to be similar to an algal chlorophyll pigment called phycoerythrin (an exact copy of which is found in the human red blood cells).

Dipterology is the study of flies.

Entomology is the study of insects and insect-like organisms. It is just one part of zoology, the other being a study of animals without backbones (vertebrates). There are more than 1,000,000 species of insects which are usually collected using nets. Insects can be found in nearly every habitat on Earth. Insects are studied because they serve a vital role in ecosystems as pollinators and recyclers of organic matter as well as food sources for other organisms like birds and spiders. They also play an important role in food chains, especially in aquatic environments where they are a vital source of food once they have been eaten by aquatic predators. Insects can be used as biological control in agriculture and pest control.

Microscopy is the use of a microscope to examine very small objects under high magnification. Microscopes are most often used in biology to study cells and microscopic organisms. They are also commonly used in forensic science and forensic entomology, where they are sometimes called scanning electron microscopes or SEMs.

Mycology is the study of fungi, a group of single-celled organisms without chlorophyll or other green photosynthetic pigments. Fungi are neither plants nor animals and are considered heterotrophs. Fungi do not have chlorophyll and cannot photosynthesize, but many species of fungi can form complete life cycles between a single spore and a gametangium and some can survive in complete darkness.

Physiology is the study of how living organisms function, the processes involved in metabolism and homeostasis, the organization of cells into tissues and organs, the distribution of fluid within and among tissues, the transmission of forces between cells and other aspects relating to biology. It is a branch of biology that involves the physiological processes and life functions of animals, including humans. The term "physiology" is often used interchangeably with the term "biology".

Preventive medicine involves measures taken for disease prevention, for example vaccinations for infectious diseases, routine cleaning of teeth to prevent cavities, or measures taken against possible natural disasters such as floods or earthquakes.
The aim of a biosecurity program is to prevent unwanted organisms from entering (and establishing in) an area and to contain or eradicate organisms that have already entered an area. Biosecurity measures may include preventative strategies such as surveillance, inspection and engineering controls and reactive strategies such as education, eradication and spraying with pesticides.

Some people may become obsessed with a particular field of study. Science nephilia is an obsession with science, scientific research and/or having an extensive knowledge of science. It is sometimes known as scientophilia or sciencing (after science). According to neurologist Oliver Sacks, the word "scientist" was invented by William Whewell in 1833 to be in opposition to the generalist—that is, those who studied "everything".

The term "worldview" was coined by the German-born American theologian Henry Nelson Wieman (1884–1975) in his book entitled "The interpretation of Christian ethics; an empirical method". Wieman defined "worldview" as "a manner of apprehending the universe, so personal and immediate that it has no necessary connection with the individual and empirical self." He suggested that worldviews differ from personal philosophies because they are not necessarily subject to verification by empirical methods.

The words "biology" and "life science" are often used interchangeably. In fact, this is a case of polysemy; both terms have different meanings depending on which biological discipline they are associated with. In general biology, life science is generally used to describe all areas of biology, while in some specific contexts biochemistry or microbiology may be more appropriate. For example, a medical scientist would describe the biology of humans whereas an environmental scientist would describe the biology of ecosystems, or an entomologist would describe the lifecycles of insects.

Scientific fields are often categorized into broad areas subject to study and research, called disciplines. Examples include anatomy, astronomy, chemistry and physics. Biologists are typically not required to be experts in all areas of their discipline and can focus on aspects that particularly interest them.

There is no standard definition of a biologist or a biological scientist, although these terms are generally understood in different ways throughout the world. Biological scientists often practice their science within a university department of biology, a research institution, or a company that performs biological research. Typically, biology students spend the first two years of post-secondary education studying general classes in biology and then specialize in one area of the discipline for the remainder of their scientific education. One distinguishing characteristic is that biological scientists use biological methods to study life, rather than human methods to study other living things.

Biological molecules and organisms are classified by taxonomists into groups called "taxa". The hierarchy of taxonomic ranks starts with species (in other words, the smallest recognized unit) at the top; groups are groups within species (e.g., orders are groups within families). These groups are then subdivided into other taxonomic ranks (e.g., genera and species within genera, families and subfamilies within families). The ranks at each level of the hierarchy form a series of larger groups, called "classes", "circles", or "subclasses". The number of distinct classes in the zoological taxonomy depends on the degree of divergence from the common ancestor. It is usually recognized that when a new class is described, so too must be defined the rank above or below it, called its "superorder", "order" or "suborder".

In addition to these standard taxonomic ranks, there are also informal groupings that recognize divergent perspectives in classification. Some examples include the grouping of living things into "kingdom" or "domain", or the grouping of Archaea into "phylum", "subphylum", or circular genetic monophyletic groups.

Karyology is the branch of biology that studies how cells cycle (i.e., come and go in an orderly manner using various processes) and how to study these processes in other organisms. Examples include karyologists who study cell division and cytokinesis in vertebrates or fungi, karyologists who study endocytosis, actinomycin transport, ciliary movements in ciliates, and so forth.

The study of genetics involves the interdisciplinary field of genetics and the life sciences, which apply the tools and concepts of biology, biochemistry and molecular biology to living organisms. Genetics is a core discipline of biology, which seeks to understand natural variation and adaptation in living organisms. It includes many sub-disciplines, such as biostatistics, evolutionary theory and microbiology.

Geneticists also study human inheritance patterns and those of domesticated species. Theoretically genetic analysis can be used to determine how two plants or animals are related; for example in crop plants or livestock breeds. In practice, molecular markers are typically used to determine the degree of relationship between individual plants or animals.

Genetics plays an important role in many aspects of science and society, ranging from crop breeding to direct applications in health care. Examples include genetic testing that can identify mutations in disease-related genes (such as BRCA1, BRCA2), or detect the presence of pathogens associated with infectious diseases.

Regulation of biological activity is mediated by protein molecules (such as enzymes and structural proteins) that serve as machines to "run" the chemistry of life by allowing cells and organisms to respond quickly to their environment. These protein molecules are encoded by genes, and the instructions for their manufacture are part of the information stored in DNA.

Thus, a major branch of molecular biology involves the use of molecular biology techniques (such as nucleic acid sequencing) to identify and characterize the function of specific genes within an organism's genetic code. This leads to the understanding of "genes" as segments of DNA that code for proteins. By extension, the full set of genes in an organism has come to be known as its "genome". The field also involves studies on how genomes change during species evolution, and on the interaction between genetics, genomics and development.

Genomics has become a sequencing technology that relies on the sequencing of DNA (or sometimes RNA), and its analysis to obtain information about an organism's genome. The availability of complete genome sequences now makes it possible to compare the DNA of different species. This provides powerful information in evolutionary studies, and also allows researchers to identify mutations involved in human disease and other biological processes.

Scientific journals which publish articles on molecular biology include "Nature", "Science", "Cell" and the "American Journal of Human Genetics". Other journals publish articles based largely on molecular biology but with a significant genetic content; for example, human genetics journals such as "American Journal of Medical Genetics" or the "Annual Review of Genetics".

Human studies and research are conducted in universities, hospitals, biotechnology and pharmaceutical companies and government institutions. In addition to the study of genes, human genetics can also be studied by studying the changes that occur in the genome as a result of mutations. These genetic changes are often caused by environmental factors or can even be due to mutagens (such as ultraviolet radiation) or aging of cells. For example, cancer researchers typically study the molecular "causes" of cancer by studying gene mutations that occur in humans with cancer (for example BRCA1, BRCA2). Cancer researchers also study "tumor suppressor genes" that regulate cell division and may be mutated in cancers.

Mechanistic studies of gene function are conducted through theoretical or computational approaches (for example, computational models or analysis of the biochemical pathways that result in a process) rather than by studying the target genes themselves. Such studies are usually done to explain or predict biological processes and often have no direct implications for clinical medicine. For example, biochemists study how starvation causes a reduction in metabolic rate, which is then found to be responsible for various diseases and aging. Computational biologists might also perform mechanistic studies by examining protein-protein interactions through computer simulation.

A study of clinical genetics is conducted in laboratories of medical laboratories equipped with automated equipment such as genetic analyzers and DNA sequencers. These laboratories also provide the clinical care for patients with disorders of autosomal dominant inheritance or those of X-linked recessive inheritance.

Biomedicine is the application of biological knowledge and techniques for the benefit of humans and other organisms. This includes advancement in general medicine, biomedical engineering, and biotechnology sectors. Biomedicine contributes to health promotion, disease prevention, diagnosis, treatment and rehabilitation. Biomedicine also has a strong effect on society by influencing legislation affecting health care policy and research funding in different countries around the world. Patents are issued for inventions in this field which can then be licensed by pharmaceutical companies to raise revenue for research projects.

Applied biology is the application of science and technology to various fields, including engineering, medicine, the environment and agriculture. Applied biology is different from basic or applied research in that it involves developing technology, business strategies and products by means of research. Applied biology may also be viewed as a part of biotechnology which can involve biological processes for uses not originally intended (such as genetic modification of food crops).

Some examples of applied biology include the use of genetically modified bacteria to produce industrial chemicals such as polyhydroxyalkanoates (this process is called "bio-oil"), which are used to make plastic films for packaging foods and other items. Some plants are genetically modified to make them resistant to herbicides (such as Roundup), which is used to eliminate weeds from crop fields.

The list of applied biology research topics is long and ever-changing. Biological agents can be used in warfare during military conflicts; for example, bioweapons such as anthrax and botulinum toxin were developed and used by the Russians against German troops in World War II. The first human gene therapy was performed by Dr. Kary Mullis in 1993, resulting in a cure for sickle cell anemia. In this procedure, genes for the production of healthy red blood cells were injected into the patient. In 2009, Chinese researchers developed a process for producing inexpensive vaccines by using bioengineered plants and insects.

Genomics is the first step in the process of understanding an organism's genome. It involves identifying and mapping all of an organism's genes as well as the control regions (promoters) required for their expression. Once mapped, genome sequences can be compared to other organisms' genome sequences to find out how they are related. This has applications in fields as diverse as evolution and medicine.

An example of genome sequencing at the level of DNA is provided by the Human Genome Project. The human genome consists of three billion base pairs, which are arranged into twenty-three pairs of chromosomes. DNA sequencing is the process of determining the order of these bases, either one at a time (shotgun sequencing) or in small overlapping chunks (whole genome shotgun sequencing). Shotgun sequencing first involves breaking up DNA into small pieces, a process called " libraries", and then sequencing these small pieces. The use of next-generation sequencing technologies has made whole genome shotgun approaches to DNA sequencing less expensive and more efficient; however, they still involve many steps and require relatively large amounts of starting material.

Molecular biology involves the study of all aspects of the biomolecule-based life process. It uses the language of cells and organisms and their constituent molecules to describe these processes. The focus is on the cellular events that integrate all of these complex organisms into communities and processes. Molecular biology allows an understanding of how cells function, how they communicate with one another, and how they become part of a community.

Because many individual characteristics in cells are encoded by genes that operate within the cell's own internal environment, it is possible to use molecular biology to study all three levels: cell to gene regulatory system, gene to protein regulatory system, and protein activity within all three levels. Thus, molecular biology can be used to understand complex processes, such as how blood clotting and disease are controlled, or how cancers are regulated.

Molecular biology is an essential part of genomics, which often involves the use of DNA sequencing to codify the individual genetic make-up of an organism or cell. Endonucleases are parts of cellular machinery that cut DNA at precise points. By using specific endonucleases and markers on cells' chromosomes (such as bioluminescence) it is possible to determine the length at which specific sections of chromosomes exist in a cell's genome. The length of the final chromosomes then corresponds to the number of DNA base pairs present in that region.

Molecular biology and genetic engineering are closely related disciplines. Genetic engineering is concerned with the isolation, manipulation and expression of specific genes within cells. Molecular biology can be used to determine which genes are expressed in a cell, as well as how they are regulated. Once a gene's structure and method of operation has been fully understood, it can be isolated by taking advantage of knowledge gained from the fields of biochemistry, chemistry, and molecular genetics. Some aspects of this knowledge have been acquired by use of recombinant DNA technology, which involves the insertion or removal of segments or even entire genes from an organism's genome (including human) via genetic engineering techniques into another organism's genome. This is also known as gene cloning. The modified genes, once isolated and purified can be studied or expressed in a cell, allowing for the development of new drugs, vaccines and medical treatments.

DNA repair describes an organism's ability to fix broken DNA molecules that occur as a result of errors in replication during DNA synthesis (see: Translesion synthesis) or exposure to exogenous agents such as ionizing radiation. It is important to note that not all organisms have the same levels of repair for every type of damage, so it is difficult to assess what specific levels are necessary for survival without further testing. In humans, not all classes of DNA damage can be repaired. For example, certain types of DNA damage can lead to genome rearrangements, which often have cancerous consequences.

Some examples of important DNA repair mechanisms in human cells are: base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR) and postreplication repair (PRR or replication-dependent repair). Each uses a different set of enzymes to perform the same general tasks. In most cases, these enzymes will be specific to the type of DNA modification that occurred. For example, BER will use a different set of enzymes than NER would for its process.

The ubiquitin / proteasome system is a major pathway for protein degradation in eukaryotes. Regulation of the ubiquitin / proteasome system by extracellular signals plays an important role in the cell cycle and in signal transduction. Ubiquitination is involved in the regulation of many signalling pathways, including those that regulate cell cycle progression, transcription, DNA replication, and apoptosis.

Cellular signalling mechanisms are used to control cellular responses such as growth or cell death to create patterns of gene expression within an organism or tissue. The purpose is to utilize internal cellular processes (such as transcription or autophagy) that can be achieved without extra-cellular influences (such as diffusion). The cell is then able to regulate its own fate. Signaling pathways are often used to achieve homeostasis in the absence of DNA damage or in response to DNA damage, such as with "Ras" and "Raf" signalling.

In addition to DNA repair enzymes, cellular processes also include DNA methyltransferases (DNMTs), which have a role in epigenetic regulation of gene expression. DNMTs act on methylated cytosine residues to change their position from guanine to cytosine within gene promoters, causing changes in chromatin structure. This results in new genes not being expressed but existing genes being expressed at different levels across the genome.

Current research aims to modify or improve DNA repair mechanisms to be able to treat diseases such as cancer, especially if the mechanism is determined to be faulty. Understanding the mechanisms that are responsible for DNA repair will allow us to build upon the work of nature and exploit our knowledge of genetics and biochemistry.

Reviews:Baur CF and Sinclair DA (2009) Essentials of human genetics, Jones & Bartlett Learning;Dutta K, Mitra A, Pal AK (2013) Human Molecular Genetics: An Introduction to Concepts, Techniques and Applications, Springer; Singh S and Singh V (2016) "Human Genetics", Springer.


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