Wednesday, 18 December 2013
- Aerobiology – the study of airborne organic particles
- Agriculture – the study of producing crops from the land, with an emphasis on practical applications
- Anatomy – the study of form and function, in plants, animals, and other organisms, or specifically in humans
- Arachnology – the study of arachnids
- Astrobiology – the study of evolution, distribution, and future of life in the universe—also known as exobiology, exopaleontology, and bioastronomy
- Biochemistry – the study of the chemical reactions required for life to exist and function, usually a focus on the cellular level
- Bioengineering – the study of biology through the means of engineering with an emphasis on applied knowledge and especially related to biotechnology
- Biogeography – the study of the distribution of species spatially and temporally
at 10:40 pm
A gene is the molecular unit of heredity of a living organism. It is widely accepted by the scientific community as a name given to some stretches of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA) that code for a polypeptide or for an RNA chain that has a function in the organism, though there still are controversies about what plays the role of the genetic material. Living beings depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring. All organisms have many genes corresponding to various biological traits, some of which are immediately visible, such as eye coloror number of limbs, and some of which are not, such as blood type, increased risk for specific diseases, or the thousands of basicbiochemical processes that
at 3:11 am
The genetic code is the set of rules by which information encoded within genetic material (DNA or mRNA sequences) is translated into proteins by living cells. Biological decoding is accomplished by the ribosome, which links amino acids in an order specified by mRNA, using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries.
at 3:10 am
Heredity is the passing of traits to offspring from its parents or ancestor. This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause somespecies to evolve. The study of heredity in biology is called genetics, which includes the field of epigenetics.
at 3:09 am
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy. Modern biology is a vast and eclectic field, composed of many branches and subdisciplines. However, despite the broad scope of biology, there are certain general and unifying concepts within it which govern all study and research, consolidating it into single, coherent field. Biology generally recognizes the cell as the basic unit of life, genes as the basic unit ofheredity, and evolution as the engine that propels the synthesis and creation of new species. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable and vital condition.
Subdisciplines of biology are defined by the scale at which organisms are studied, the kinds of organisms studied, and the methods used to study them: biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions among biological molecules; botany studies the biology of plants; cellular biology examines the basic building block of all life, the cell; physiologyexamines the physical and chemical functions of tissues, organs, and organ systems of an organism; evolutionary biology examines theprocesses that produced the diversity of life; and ecology examines how organisms interact in their environment.
at 3:08 am
Genetics (from Ancient Greek γενετικός genetikos, "genitive" and that from γένεσις genesis, "origin"), a discipline of biology, is the science of genes,heredity, and variation in living organisms.
Genetics is the process of trait inheritance from parents to offspring, including the molecular structure and function of genes, gene behavior in the context of acell or organism (e.g. dominance and epigenetics), gene distribution, and variation and change in populations (such as through Genome-Wide Association Studies). Given that genes are universal to living organisms, genetics can be applied to the study of all living systems; including bacteria, plants, animals, andhumans. The observation that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals throughselective breeding. The modern science of genetics, seeking to understand this process, began with the work of Gregor Mendel in the mid-19th century.
Mendel observed that organisms inherit traits by way of discrete 'units of inheritance.' This term, still used today, is a somewhat ambiguous definition of agene. A more modern working definition of a gene is a portion (or sequence) of DNA that codes for a known cellular function. This portion of DNA is variable, it may be small or large, have a few subregions or many subregions. The word 'Gene' refers to portions of DNA that are required for a single cellular process or single function, more than the word refers to a single tangible item. A quick idiom that is often used (but not always true) is 'one gene, one protein' meaning a singular gene codes for a singular protein type in a cell. Another analogy is that a 'gene' is like a 'sentence' and 'nucleotides' are like 'letters'. A series of nucleotides can be put together without forming a gene (non-coding regions of DNA), like a string of letters can be put together without forming a sentence (babble). Nonetheless, all sentences must have letters, like all genes must have a nucleotides.
The sequence of nucleotides in a gene is read and translated by a cell to produce a chain of amino acids which in turn spontaneously fold into proteins. The order of amino acids in a protein corresponds to the order of nucleotides in the gene. This relationship between nucleotide sequence and amino acid sequence is known as the genetic code. The amino acids in a protein determine how it folds into its unique three-dimensional shape; a structure that is ultimately responsible for the proteins function. Proteins carry out many of the functions needed for cells to live. A change to the DNA in a gene can change a protein's amino acid sequence, thereby changing its shape and function, rendering the protein ineffective or even malignant (see: sickle cell anemia). When a gene change occurs, it is referred to as a mutation.
Although genetics plays a large role in the appearance and behavior of organisms, it is a combination of genetics with the organisms' experiences (aka. environment) that determines the ultimate outcome. Genes may be activated or inactivated, which is determined by a cell's or organism's environment, intracellularly and/or extracellularly. For example, while genes play a role in determining an organism's size, the nutrition and health it experiences after inception also have a large effect.
at 3:07 am
In chemistry, and especially in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic tail (chain), which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from triglycerides or phospholipids. When they are not attached to other molecules, they are known as "free" fatty acids. Fatty acids are important sources of fuel because, when metabolized, they yield large quantities of ATP. Many cell types can use either glucose or fatty acids for this purpose. In particular, heart and skeletal muscle prefer fatty acids. Despite long-standing assertions to the contrary, the brain can use fatty acids as a source of fuel in addition to glucose and ketone bodies.
at 2:52 am
Glycerol (or glycerine, glycerin) is a simple polyol (sugar alcohol) compound. It is a colorless, odorless, viscous liquid that is widely used inpharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids known as triglycerides. Glycerol is sweet-tasting and of low toxicity.
at 2:51 am
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries as well as in nanotechnology.
Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks":ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acids,glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).
Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids calledtriglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-,monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol.Although humans and other mammals use various biosynthetic pathways to both break down and synthesize lipids, some essential lipids cannot be made this way and must be obtained from the diet.
at 2:50 am
Nuclear magnetic resonance spectroscopy of proteins (usually abbreviated protein NMR) is a field of structural biology in which NMR spectroscopy is used to obtain information about the structure and dynamics of proteins, and also nucleic acids, and their complexes. The field was pioneered by Richard R. Ernst and Kurt Wüthrich, among others. Structure determination by NMR spectroscopy usually consists of several phases, each using a separate set of highly specialized techniques. The sample is prepared, measurements are made, interpretive approaches are applied, and a structure is calculated and validated.
NMR involves the quantum mechanical properties of the central core ("nucleus") of the atom. These properties depend on the local molecular environment, and their measurement provides a map of how the atoms are linked chemically, how close they are in space, and how rapidly they move with respect to each other. These properties are fundamentally the same as those used in the more familiar Magnetic Resonance Imaging (MRI), but the molecular applications use a somewhat different approach, appropriate to the change of scale from millimeters (of interest to radiologists) to nano-meters (bonded atoms are typically a fraction of a nano-meter apart), a factor of a million. This change of scale requires much higher sensitivity of detection and stability for long term measurement. In contrast to MRI, structural biology studies do not directly generate an image, but rely on complex computer calculations to generate three dimensional molecular models.
Currently most samples are examined in a solution in water, but methods are being developed to also work with solid samples. Data collection relies on placing the sample inside a powerful magnet, sending radio frequency signals through the sample, and measuring the absorption of those signals. Depending on the environment of atoms within the protein, the nuclei of individual atoms will absorb different frequencies of radio signals. Furthermore the absorption signals of different nuclei may be perturbed by adjacent nuclei. This information can be used to determine the distance between nuclei. These distances in turn can be used to determine the overall structure of the protein.
A typical study might involve how two proteins interact with each other, possibly with a view to developing small molecules which can be used to probe the normal biology of the interaction ("chemical biology") or to provide possible leads for pharmaceutical use ("drug development"). Frequently, the interacting pair of proteins may have been identified by studies of human genetics, indicating the interaction can be disrupted by unfavorable mutations, or they may play a key role in the normal biology of a "model" organism like the fruit fly, yeast, the worm C. elegans, or mice. To prepare a sample, methods of molecular biology are typically used to make quantities by bacterial fermentation. This also permits changing the isotopic composition of the molecule, which is desirable because the isotopes behave differently and provide methods for identifying overlapping NMR signals.
at 2:48 am