(physiology) A process in which one substance permeates another. A
fluid permeates or is dissolved by a liquid or solid. Skin absorption is a route by which substances can enter the body through the skin.
(biochemistry) Acetyl coenzyme A is a molecule participating in many
biochemical reactions in carbohydrate, protein and lipid
metabolism. Its main function is to deliver the
acetyl group to the
citric acid cycle (Krebs cycle) to be
oxidized for energy production.
(evolutionary biology, population biology) Term can apply to an individual organism's adaptation to its environment, the adaptation of organisms to an environment through evolutionary processes, or the population dynamics intrisic to the evolutionary process.
(biochemistry) A class of
organic compounds containing an
amine group and a
carboxylic acid group which function as the fundamental building blocks of
proteins and play important roles in many other biochemical processes.
The process by which humans use
animal breeding and
plant breeding to
selectively control the development of particular
phenotypictraits in organisms by choosing which individual organisms will
reproduce and create
offspring. While the deliberate exploitation of knowledge about
genetics and
reproductive biology in the hope of producing desirable characteristics is widely practiced in
agriculture and experimental biology, artificial selection may also be unintentional and may produce unintended (desirable or undesirable) results.
An organism capable of producing complex
organic compounds from simple substances present in its surroundings, generally by using energy from sunlight (as in
photosynthesis) or from inorganic chemical reactions (as in
chemosynthesis). Autotrophs do not need to consume another living organism in order to obtain energy or organic carbon, as opposed to
heterotrophs.
An enormous and diverse clade of microscopic,
prokaryotic, single-celled organisms which lack a true
nucleus. They represent one of the three fundamental biological
domains.
The inactive
X chromosome in a female somatic cell, rendered inactive in a process called
lyonization, in those species in which sex is
determined by the presence of the
Y chromosome (including humans) or
W chromosome rather than by the presence of two X chromosomes or two
Z chromosomes.
An organelle formed from a
centriole, and a short cylindrical array of microtubules. Also called a basal granule, a kinetosome, and in older cytological literature, a blepharoplast.
A dark green to yellowish-brown fluid, produced by the liver of most vertebrates, which aids the digestion of
lipids in the small intestine. Also called gall.
A formal system of classifying
species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages.
The process of
catalysis in biological systems. In biocatalytic processes, natural catalysts, such as protein enzymes, perform chemical transformations on organic compounds.
The study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area.
Organic matter derived from living or recently living organisms. Biomass can be used as a source of energy and it most often refers to plants or plant-based materials which are not used for food or feed, and are specifically called lignocellulosic biomass.
Any very large
ecological area on the Earth's surface containing fauna and flora (animals and plants) adapting to their environment. Biomes are often defined by
abiotic factors such as climate, topographical relief, geology, soils, and water resources.
The study of the structure and function of biological systems by means of the methods of "mechanics", which is the branch of physics involving analysis of the actions of forces.
The pursuit of answers to medical questions. These investigations lead to discoveries, which in turn lead to the development of new preventions, therapies, and cures for problems in human and veterinary health. Biomedical research generally takes two forms: basic science and applied research.
Biotechnology is the use of living systems and organisms to develop or make products, or "any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use" (UN Convention on Biological Diversity).
A
body fluid that circulates in humans and other vertebrate animals and is generally responsible for delivering necessary substances such as
oxygen and nutrients between the cells and tissues of the body and transporting
metabolic waste products away from those same cells and tissues.
A semipermeable membrane separating the blood from the cerebrospinal fluid, and constituting a barrier to the passage of cells, particles, and large molecules.
The basic structural and functional unit of all living
organisms, and the smallest functional unit of
life. A cell may exist as an independent, self-replicating unit (as in the case of
unicellular organisms), or in cooperation with other cells, each of which may be specialized for carrying out particular functions within a larger
multicellular organism. Cells consist of
cytoplasm enclosed within a
cell membrane and sometimes a
cell wall, and serve the fundamental purpose of separating the controlled environment in which biochemical processes take place from the outside world. Most cells are visible only under a
microscope.
The branch of biology that studies the structure and function of living
cells, including their
physiological properties,
metabolic processes, chemical composition,
life cycle, the
organelles they contain, and their interactions with their environment. This is done at both
microscopic and
molecular levels.
The ordered series of events which take place in a
cell leading to
duplication of its genetic material and ultimately the
division of the
cytoplasm and
organelles to produce two or more daughter cells. These events can be broadly divided into phases of growth and division, each of which can vary in duration and complexity depending on the tissue or organism to which the cell belongs. Cell cycles are essential processes in all
unicellular and
multicellular organisms.
A tough, often rigid structural barrier surrounding certain types of
cells (such as in
fungi,
plants, and most
prokaryotes) that is immediately external to the
cell membrane.
A framework for understanding the movement of
genetic information between information-carrying
biopolymers within biological systems. Popularly (though simplistically) stated as "
DNA makes
RNA and RNA makes
protein", the principle attempts to capture the notion that the transfer of genetic information only naturally occurs between certain classes of molecules and in certain directions.
An
organelle that is the primary site at which
microtubules are organized. They occur only in plant and animal cells and help to regulate
cell division.
A chemical substance consisting of two or more different
chemically bondedelements, with a fixed ratio determining the composition. The ratio of each element is usually expressed by a
chemical formula.
The state in which both reactants and products are present in concentrations which have no further tendency to change with time in a chemical reaction.
A branch of the physical sciences that studies the composition, structure, properties, and change of
matter. Chemical interactions underlie all biological processes.
A type of highly specialized
organelle in the cells of
plants and
algae, the main role of which is to conduct
photosynthesis, by which the photosynthetic pigment
chlorophyll captures the energy from sunlight and converts and stores it in the molecules
ATP and
NADPH while freeing oxygen from water.
A type of
lipid molecule that is
biosynthesized by all
animal cells because it is an essential structural component of animal
cell membranes, essential for maintaining both membrane structural integrity and fluidity.
Also called the Krebs cycle and tricarboxylic acid cycle (TCA).
A series of chemical reactions used by all
aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from
carbohydrates,
fats, and
proteins into
carbon dioxide and chemical energy in the form of
guanosine triphosphate (GTP). In addition, the cycle provides the chemical precursors for certain
amino acids as well as the reducing agent
NADH that is used in numerous other biochemical reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular
metabolism and may have originated abiogenically.
A scientific theory in
immunology that explains the functions of cells (
lymphocytes) of the
immune system in response to specific
antigens invading the body. The theory has become the widely accepted model for how the immune system responds to
infection and how certain types of
B and
T lymphocytes are selected for destruction of specific antigens.[2]
The process of producing individual organisms or molecules with identical or virtually identical
DNA, either naturally or artificially. Many organisms, such as
bacteria, insects, and
plants, are capable of naturally producing clones through
asexual reproduction. In
biotechnology, cloning refers to the artificial creation of copies of cells, DNA fragments, or other
biomolecules by various laboratory techniques.
In the context of virus capsid, may refer colloquially to the defined geometric structure of a capsid, or the membrane of an endosome containing an intact virion. The coat of a virus is used in descriptions for the general public. Related slang: uncoating.
The use of
comparative methods to study the similarities and differences between two or more biological organisms (e.g. two organisms from the same time period but different
taxa, or two organisms from the same taxon but different times in evolutionary history). The side-by-side comparison of
morphological or
molecular characteristics of different organisms is the basis from which biologists infer the organisms' genetic relatedness and their natural histories. It is a fundamental tool in many biological disciplines, including
anatomy,
physiology,
paleontology, and
phylogenetics.
The scientific study of nature and of Earth's
biodiversity with the aim of protecting
species, their
habitats, and
ecosystems from excessive rates of
extinction and the erosion of biotic interactions.
An
evolutionary process by which
species of different lineages independently develop similar characteristics, often to the point that the species appear to be more closely related than they actually are.
The crossover of some property, usually heat or some component, between two fluids flowing in opposite directions to each other. The phenomenon occurs naturally but is also frequently mimicked in industry and engineering.
One of the four main nitrogenous bases found in both
DNA and
RNA, along with
adenine,
guanine,
thymine, and
uracil (in RNA); it is a
pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at position 2).
A complex, dynamic network of interlinking
protein filaments that extends from the
cell nucleus to the
cell membrane and which is present in the
cytoplasm of all
cells, including
bacteria and
archaea.[3] The cytoskeletal systems of different organisms are composed of similar proteins. In eukaryotes, the cytoskeletal matrix is a dynamic structure composed of three main proteins, which are capable of rapid growth or disassembly dependent on the cell's requirements.[4]
The
genetic contribution of an individual to the next
generation's
gene pool relative to the average for the population, usually measured by the number of
offspring or close kin that survive to
reproductive age.
Deciduous means "falling off at maturity" or "tending to fall off", and it is typically used in
botany in order to refer to
trees or
shrubs that lose their
leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruits when ripe.
The process by which the
organic compounds of deceased organisms are broken down into simpler organic or
inorganic matter such as
carbon dioxide,
water, simple sugars, and mineral salts. These reactions occur naturally by both
biotic means (
biodegradation, such as that practiced by many
bacteria and
fungi) and
abiotic means (basic physical and chemical processes, such as
hydrolysis). Decomposition recycles matter present in the
biosphere, making it an essential part of the
nutrient cycle. Organisms that facilitate decomposition are known as
decomposers; the scientific study of decomposition is known as
taphonomy.
Any
organism that facilitates the breakdown of dead or decaying organisms by carrying out the
decomposition of complex biomolecules into simpler substances. Decomposers are
heterotrophs which obtain energy and nutrition for their own growth and reproduction by recycling the chemical compounds contained in organic substrates. Microorganisms such as
bacteria and
fungi are the biosphere's chief decomposers, but
invertebrates such as
earthworms are also sometimes considered decomposers.
A process in which
proteins or
nucleic acids lose the quaternary, tertiary, and secondary structure which is present in their native state, when exposed to some external stress or chemical compound such as a strong acid or base, a concentrated inorganic salt, or an organic solvent.
The microbially facilitated process of
nitratereduction that ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous
nitrogen oxide products. It is performed by a large group of heterotrophic facultative anaerobic
bacteria and is a fundamental component of the
nitrogen cycle.
A
nucleic acidpolymer that serves as the fundamental hereditary material in all living organisms. Each DNA molecule is composed of long sequences of
nucleotides, each of which includes one of four
nitrogenous bases –
adenine (abbreviated A),
cytosine (C),
guanine (G), and
thymine (T) – attached to a sugar-phosphate complex which acts as a "backbone" for the long-chain polymer. DNA most commonly occurs in "double-stranded" form, i.e. as a pair of nucleotide polymers bound together by
complementarybase pairing.
The process of reversing the charge across a
cell membrane (such as that of a
neuron), thereby causing an
action potential. In depolarization, the inside of the membrane, which is normally negatively charged, becomes positive and the outside becomes negative. This is brought about by positively charged
sodium ions rapidly passing into the
axon.
The branch of biology that studies the processes by which living organisms grow and develop over time. The field may also encompass the study of
reproduction,
regeneration,
metamorphosis, and the growth and differentiation of
stem cells in mature tissues.
Any particular abnormal condition that negatively affects the structure or function of all or part of a living organism and that is not the result of any immediate external injury. Diseases are medical conditions that are often identifiable by specific
signs and
symptoms. They may be caused by external factors such as infectious
pathogens or by internal dysfunctions such as immune deficiency or
senescence.
The chemical duplication or copying of a
DNA molecule; the process of producing two identical copies from one original DNA molecule, in which the
double helix is unwound and each strand acts as a template for the next strand. Complementary nucleotide bases are matched to synthesize the new partner strands.
Any substance that causes a change in an organism's
physiology or
psychology when consumed. Drugs may be naturally occurring or artificially produced, and consumption may occur in a number of different ways. Drugs are typically distinguished from substances that provide nutritional support such as food.
dimorphism
The existence of a
morphological distinction between organisms of the same
species, such that individuals of that species occur in one of two distinct forms which differ in one or more characteristics, such as colour, size, shape, or any other
phenotypic trait. Dimorphism based on sex – e.g. male vs. female – is common in
sexually reproducing organisms such as plants and animals.
The efficiency with which
energy is transferred from one
trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an
ecosystem.
The scientific analysis and study of interactions between
organisms and their
environment. It is an interdisciplinary field that combines concepts from biology,
geography, and
Earth science.
In evolutionary ecology, a genetically distinct geographic variety,
population, or
race within a
species which is adapted to specific environmental conditions.
The outermost layer of cells or tissue of an
embryo in early development, or the parts derived from this, which include the
epidermis, nerve tissue, and
nephridia.
An
organism in which internal
physiological sources of heat are of relatively small or quite negligible importance in controlling
body temperature compared to ambient sources of heat. Ectotherms generally experience changes in body temperature that closely match changes in the temperature of their environment; colloquially, these organisms are often referred to as "cold-blooded". Contrast endotherm.
Conducted or conducting outwards or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied). Contrast afferent.
The organic vessel containing the
zygote in which an animal
embryo develops until it can survive on its own, at which point the developing organism emerges from the egg in a process known as hatching.
A gradient of
electrochemical potential, usually for an
ion that can move across a
membrane. The gradient consists of two parts: the electrical potential and the difference in chemical concentration across the membrane.
Any chemical entity that accepts
electrons transferred to it from another chemical entity. It is an
oxidizing agent that, by virtue of its accepting electrons, is itself
reduced in the process. Contrast electron donor.
Any of various molecules that are capable of accepting one or two electrons from one molecule and donating them to another in the process of
electron transport. As the electrons are transferred from one electron carrier to another, their energy level decreases, and energy is released.
A chemical entity that donates electrons to another chemical entity. It is a
reducing agent that, by virtue of its giving up its electrons, is itself
oxidized in the process. Contrast electron acceptor.
A type of
microscope that uses a beam of
electrons to create an image of a sample or specimen. Electron microscopes are capable of much higher magnifications and have greater resolving power than conventional light microscopes, allowing them to see much smaller objects in finer detail.
The branch of biology that studies the development of
gametes (sex cells), fertilization, and development of
embryos and
fetuses. Additionally, embryology involves the study of
congenital disorders that occur before birth.
Any
species which is very likely to become
extinct in the near future, either worldwide or in a particular area. Such species may be threatened by factors such as habitat loss, hunting, disease, and climate change, and most have a declining population or a very limited range.
The ecological state of an organism or species being unique to a defined geographic location, such as an island, nation, country, habitat type, or other defined zone. Organisms are said to be endemic to a place if they are indigenous to it and found nowhere else.
The collection of
glands that produce
hormones which regulate
metabolism, growth and development, tissue function, and a wide variety of other biological processes.
A form of
active transport in which a cell transports molecules such as
proteins into the cell's interior by engulfing them in an energy-consuming process.
One of the three primary germ layers in the very early human
embryo. The other two layers are the
ectoderm (outside layer) and
mesoderm (middle layer), with the endoderm being the innermost layer.
A type of
organelle found in
eukaryotic cells that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures known as cisternae.
An evolutionary theory regarding the origin of
eukaryotic cells from a hypothetical internal
symbiosis between
prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist
Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by
Lynn Margulis in 1967.
An organism that is capable of maintaining a consistent,
metabolically favorable
body temperature, largely by the recycling of heat released by its internal
physiological functions, instead of by relying on ambient sources of heat. Endotherms are generally able to maintain a stable body temperature despite changes in the temperature of their environment; colloquially, these organisms are often referred to as "warm-blooded". Contrast ectotherm.
A
protein that acts as a biological
catalyst by accelerating chemical reactions.
Metabolic pathways depend upon enzymes to catalyze their individual steps, and almost all metabolic processes require
enzyme catalysis in order to occur at rates fast enough to sustain life.
The study and analysis of the patterns, causes, and effects of health and
disease conditions in defined
populations. It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare.
A sub-field of
genetics that studies cellular and physiological phenotypic trait variations caused by external or environmental factors which affect how cells
expressgenes, as opposed to those caused by changes in the
DNA sequence.
An organism that grows on the surface of a
plant and derives moisture and
nutrients from the air, rain, marine environments, or from debris accumulating around it.
A
nutrient required for normal
physiological function which cannot be synthesized by a particular organism, either at all or in sufficient quantities, and which therefore must be obtained from external sources such as food. In humans, a set of nine
amino acids, two
fatty acids, thirteen
vitamins, and fifteen
minerals are considered essential nutrients.
The scientific study of non-human animal behaviour (i.e. excluding human behaviour) and usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait.
A type of organism consisting of cells which have a
nucleus enclosed within a distinct
nuclear membrane, unlike
prokaryotes. Eukaryotes include all organisms except the bacteria and archaea (i.e. all plants, animals, fungi, and protists are eukaryotes).
The subfield of biology that studies
evolution and the evolutionary processes that produced the diversity of life on Earth from a hypothesized single
common ancestor. These processes include the descent of
species and the origin of new species.
A form of active transport and bulk transport in which a cell transports molecules out of the cell by expelling them through an energy-dependent process.
(of a substance or process) Originating outside of or external to a system (such as an organism, tissue, or cell), as with
drugs and many
pathogens. Contrast endogenous.
It is exhibited when the rate of change of the value of a mathematical function is proportional to the function's current value, resulting in its value at any time being an exponential function of time.
The termination of the existence of a particular kind of
organism or a particular
taxon, often a
species, as a result of the death of the last individual of the taxon (though the capacity to breed and recover may have been lost before this point, rendering the taxon
functionally extinct).
An organism which is capable of producing
energy through
aerobic respiration and then switching to
anaerobic respiration depending on the amounts of oxygen and fermentable material in the environment.
An open hole that is present in extant or extinct amniotes. Foramina inside the body of animals typically allow muscles, nerves, arteries, veins, or other structures to connect one part of the body with another.
A family of
proteins that act as molecular switches inside
cells, and are implicated in transmitting signals from a diversity of stimuli outside a cell to its interior.
Any segment of
DNA that contains the information necessary to produce a functional
RNA and/or
protein product in a controlled manner. Genes are often considered the fundamental molecular units of
heredity. The transmission of genes from a parent cell or organism to its
offspring is the basis of the inheritance of
phenotypic traits.
Variations of
genomes between members of species, or between groups of species thriving in different parts of the world as a result of
genetic mutation. Genetic diversity in a population or species is a result of new gene combinations (e.g.
crossing over of chromosomes), genetic mutations,
genetic drift, etc.
An organ found in the
digestive tract of some animals, including
archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some
gastropods, some
fish, and some
crustaceans.
The passing on of
phenotypictraits from parents to their
offspring, either through
sexual or
asexual reproduction. Offspring cells and organisms are said to inherit the genetic information of their parents.
Any member of a class of signaling molecules produced by
glands in
multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.
Any living organism that harbors another living organism (known as a "guest" or
symbiont), whether the guest is
parasitic,
mutualistic, or
commensalist in its interactions with the host. The guest typically receives shelter and nourishment from the host.
An organic compound consisting entirely of hydrogen and carbon atoms. Hydrocarbons from which one hydrogen atom has been removed are functional groups called hydrocarbyls.
The branch of biology devoted to the study of
fish, including bony fishes (
Osteichthyes), cartilaginous fish (
Chondrichthyes), and jawless fish (
Agnatha).
Any of a class of
glycoprotein molecules produced by plasma cells (white blood cells) which act as a critical part of the immune response by specifically recognizing and binding to particular
antigens, such as bacteria or viruses, and aiding in their destruction. They are a major component of the group of immune defense molecules collectively called
antibodies.
The invasion of an organism's cells or tissues by a
disease-causing
pathogen, its growth and/or multiplication, and the reaction of the
host organism to the infectious agent and the
toxins it produces. The variety of biological pathogens capable of causing infections includes certain
bacteria,
viruses,
fungi,
protists,
parasitic worms, and
arthropods.
An anabolic peptide hormone produced in the
pancreas which helps to regulate the
metabolism of carbohydrates, fats, and protein by promoting the absorption of
glucose from the blood into liver, fat, and skeletal muscle cells. Abnormal insulin activity is the cause of
diabetes mellitus.
A group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, or tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their antiviral defenses.
(French: Système international d'unités; abbreviated SI) The modern standardized form of the metric system of units and measurements, and the system of measurement formally adopted for use in the physical and natural sciences.
Also called an exotic species, foreign species, alien species, non-native species, or non-indigenous species.
Any
species living outside its
native geographic
range, and which has arrived there either by accidental or deliberate human activity. Such human-caused introduction of species to foreign environments is distinguished from biological
colonization, by which species spread to new areas through "natural" means (i.e. without the involvement of humans).
A group of
animals that have no backbone, unlike animals such as reptiles, amphibians, fish, birds, and mammals, which all have a backbone. Among the many extant invertebrate
phyla are the
Cnidaria,
Mollusca,
Annelida,
Nematoda, and
Arthropoda.
A type of chemical bond involving the complete transfer of valence electron(s) between two atoms. Such bonds typically occur between elements characterized as metals and nonmetals, and generate two oppositely charged ions: the metal loses electrons to become a positively charged
cation, and the nonmetal accepts those electrons to become a negatively charged
anion.
A molecule with the same chemical formula as another molecule, but with a different chemical structure. That is, isomers contain the same number of atoms of each element, but have different arrangements of their atoms.
Refers to two solutions having the same osmotic pressure across a semipermeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.
A distinct juvenile form many
animals undergo before
metamorphosis into adults. Animals with indirect development, such as insects, amphibians, or cnidarians, typically have a larval phase of their
life cycle.
The principle, originally formulated by
Gregor Mendel, stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.
A colourless cell of the
immune system which circulates in the
blood and body fluids and is involved in counteracting foreign substances and
disease. There are several types of leukocytes, all amoeboid cells with a nucleus, including
lymphocytes,
granulocytes, and
monocytes.
The characteristic or collection of characteristics that distinguishes physical entities that undergo biological processes (e.g. living organisms) from that those do not (e.g. non-living, inanimate matter), either because such processes have ceased or because they were not present in the first place. What constitutes "life" is notoriously difficult to define, and there is currently no consensus definition, though some popular criteria are that living things are composed of
cells, have a
life cycle, undergo
metabolism, maintain
homeostasis,
adapt to environments, respond to
stimuli,
reproduce, and
evolve.
Biology is the scientific study of life and of living organisms.
The fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.
Any set of one or more
genes which are sufficiently close together on the same chromosome that they are very unlikely to assort independently and therefore are usually inherited together.
A substance that is insoluble in water and soluble in alcohol, ether, and chloroform. Lipids are an important component of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells. Cholesterol and triglycerides are lipids.
A biochemical assembly that contains both proteins and lipids, bound to the proteins, which allow fats to move through the water inside and outside cells. The proteins serve to emulsify the lipid molecules.
Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle – the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.
Evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.
A very large molecule, such as a protein, commonly created by polymerization of smaller subunits (monomers). They are typically composed of thousands or more atoms.
Nutrients needed in large amounts which provide calories or energy. Nutrients are substances needed for growth, metabolism, and for other body functions. There are three basic types of macronutrients: fats, proteins, and carbohydrates.
A kind of swallowing cell, which means it functions by literally swallowing up other particles or smaller cells. Macrophages engulf and digest debris (such as dead cells) and foreign particles through the process of
phagocytosis, so macrophages act like scavengers.
The branch of biology that studies
mammals, a class of
vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems.
The study of organisms in the ocean or other marine bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.
A cell filled with basophil granules, found in numbers in connective tissue and releasing histamine and other substances during inflammatory and allergic reactions.
A specialized type of
cell division in which a dividing parent cell proceeds through two consecutive divisions, ultimately producing four genetically unique daughter cells in each of which the
chromosome number is half of that in the original parent cell. This process is exclusive to cells of the sex organs in
sexually reproducingeukaryotes, where it serves the purpose of generating
gametes such as
eggs,
sperm, or
spores.
When a nerve or muscle cell is at "rest", its membrane potential is called the resting membrane potential. In a typical neuron, this is about –70 millivolts (mV). The minus sign indicates that the inside of the cell is negative with respect to the surrounding extracellular fluid.
The third phase of mitosis, in which duplicated genetic material carried in the nucleus of a parent cell is separated into two identical daughter cells. During metaphase, the cell's chromosomes align themselves in the middle of the cell through a type of cellular "tug of war".
The study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents.
The smallest particle in a chemical element or compound that has the chemical properties of that element or compound. Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms.
The branch of biology concerning biological activity at the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular with genetics and biochemistry.
A neuron whose cell body is situated in the motor
cortex,
brain stem, or the
spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.
The branch of biology concerned with the study of
fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicine, food, and entheogens, as well as their dangers, such as poisoning or infection.
A process in nature in which organisms possessing certain
genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or
frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations.
The role and position an organism or taxon fills within its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.
The chemical process by which molecular
nitrogen (N2) in the air is converted into
ammonia (NH3) or related nitrogenous compounds, typically by specialized microorganisms in soil and aquatic ecosystems but also by certain non-biological processes. Despite comprising nearly 80% of the gas in the Earth's atmosphere, diatomic nitrogen is metabolically useless to all but a few microorganisms, known as
diazotrophs. Nitrogen fixation is essential to all life on Earth because fixed inorganic nitrogenous compounds are required for the
biosynthesis of all nitrogen-containing organic compounds, including
amino acids and
nucleic acids.
The nitrogen-containing biological compounds that form
nucleosides, which in turn are components of
nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids.
An organic compound which serves as the fundamental
monomer used in the construction of
nucleic acid polymers, such as
DNA and
RNA, both of which are essential biomolecules within all living organisms.
The spontaneous net movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.
The study of the history of life on Earth as reflected in the
fossil record. Fossils are the remains or traces of organisms that lived in the geological past and have been preserved in the Earth's crust.
The study of
parasites, their
hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, but by their way of life.
In the broadest sense, anything that can produce
disease, though the term is most commonly used to refer specifically to an infectious
microscopic organism such as a
virus,
bacterium,
protozoan, or another microbial agent which causes disease for a
host organism by invading the host's tissues.
A medical specialty that is concerned with the diagnosis of
disease based on the laboratory analysis of bodily fluids such as
blood and
urine, as well as
tissues, using the tools of chemistry, clinical microbiology, hematology, and molecular pathology.
A numeric scale used to specify the acidity or basicity (alkalinity) of an aqueous solution. It is roughly the negative of the logarithm to base 10 of the concentration, measured in units of moles per liter, of hydrogen ions.
The science of
drug action on biological systems. In its entirety, it embraces knowledge of the sources, chemical properties, biological effects, and therapeutic uses of drugs.
The composite of an organism's observable features or traits, such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior.
A secreted or excreted chemical factor that triggers a social response in members of the same
species. Pheromones are analogous to
hormones acting outside the body of the secreting individual to impact the behavior of receiving individuals.
The process by which nearly all
plants and some
algae and
bacteria convert the energy of sunlight into chemical energy, which is used to synthesize
carbohydrates such as
sugars from
carbon dioxide and water; these carbohydrates are stored as food, and the energy within them is later released to fuel
metabolic activities. Organisms that perform photosynthesis are therefore
autotrophs. Photosynthesis supplies the majority of the energy necessary for life on Earth.
The transfer of
pollen from a male part of a plant to a female part of a plant, enabling later fertilisation and the production of seeds. Pollen is most commonly transported by animals or by wind.
A technique used in
molecular biology to amplify a single copy or a few copies of a segment of
DNA across several orders of magnitude, generating thousands to millions of copies of a particular
DNA sequence.
A subfield of
ecology that deals with the dynamics of species
populations and how these populations interact with the environment. It is the study of how the population sizes of species change over time and space.
Also called behavioral neuroscience, biological psychology, and biopsychology.
The application of the principles of biology to the study of physiological, genetic, and developmental mechanisms of behavior in humans and other animals.
The process of renewal, restoration, and growth that makes
genomes,
cells,
organisms, and
ecosystems resilient to natural fluctuations or events that cause disturbance or damage. For example, many organisms are capable of regenerating
tissues and even entire body parts if they are lost or destroyed.
The biological process by which one or more new individual
organisms (known as
offspring) is produced from an existing
parent organism. Reproduction is a defining characteristic of all
life, and every individual organism exists as the result of a reproductive event. There are two general methods by which reproduction takes place:
sexual or
asexual.
The branch of biology that studies the various types and mechanisms of
reproduction used by living organisms, typically with special emphasis on
cell division,
fertility,
endocrinology, and/or the
tissues,
organs, and systems involved in reproduction.
1. Generally, lacking motility or means of self-locomotion; immobile or incapable of movement. Sessile organisms may move via external forces such as wind or water currents but are more often permanently fixed to a solid object such as a rock, soil, or another organism.
2. In
botany, the property of a
plant or plant part that is attached directly by its base to an object or another plant part, i.e. without an intervening
stem, stalk, or
petiole.
A branch of biology that is based on the hypothesis that social behavior has resulted from
evolution and which attempts to explain and examine social behavior within that context.
The basic unit of biological classification and the narrowest of the canonical
taxonomic ranks, as well as a unit of
biodiversity. Species are traditionally distinguished on the basis of
reproductive compatibility, though achieving a satisfactory definition that is universally applicable to all life has proven difficult, since many organisms classified as distinct "species" are capable of interbreeding with different (albeit closely related) species, generating
hybrids.
A type of undifferentiated or partially undifferentiated
cell that is capable of differentiating into other types of specialized cells and also capable of
dividing to produce more of the same type of stem cell. Stem cells are the earliest type of cell in a
cell lineage.
A genetic variant, subtype, or
culture identified as a distinct
taxonomic subdivision within a
species. The term is most commonly used to identify particular types of
bacteria and
viruses.
Any close and long-term interaction between two different biological
organisms, regardless of the nature or degree of the effect on either organism. Examples include
mutualism,
commensalism, and
parasitism.
The scientific study of
biodiversity. It is concerned with the discovering and naming of new
species of organisms (nomenclature) and arranging these
taxa into classification schemes (
taxonomy). A large part of modern systematics is concerned with understanding the evolutionary relationships between various taxa (
phylogenetics) using methods of
comparative biology (e.g.
physiology, behavior, biochemistry,
morphology,
genetics) and statistical analysis.
A group of one or more populations of an
organism or organisms used by
taxonomists to classify organisms into discrete, convenient, and identifiable units.
The decomposition of a viral capsid. An informal and simplified description of the way a virus infectious material enters the cell, usually appearing in light science material for the general public.
The retention during the process of
evolution of genetically determined structures or attributes that have lost some or all of their ancestral function in a given
species.
A submicroscopic, infectious,
parasitic particle of genetic material contained in a protein coat and which replicates only inside the living cell of a
host organism.
The branch of biology that studies the
animal kingdom, including the
structure,
embryology,
evolution,
classification, habits, and geographical distribution of all animals, both living and extinct, and how they interact with their
ecosystems.
^Hardin J, Bertoni G, Kleinsmith LJ (2015). Becker's World of the Cell (8th ed.). New York: Pearson. pp. 422–446.
ISBN978013399939-6.
^McKinley, Michael; Dean O'Loughlin, Valerie; Pennefather-O'Brien, Elizabeth; Harris, Ronald (2015). Human Anatomy (4th ed.). New York: McGraw Hill Education. p. 29.
ISBN978-0-07-352573-0.