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Enzyme

An enzyme is a protein molecule in cells which works as a biological catalyst. Enzymes speed up chemical reactions in the body, but do not get used up in the process, therefore can be used over and over again. Almost all biochemical reactions in ...

                                               

Fatty acid

A fatty acid is a carboxylic acid OH), with a long unbranched hydrocarbon tail. It is studied in organic chemistry and biochemistry. Fatty acids are important sources of body fuel. When metabolized, they yield large quantities of ATP. Many cell t ...

                                               

Insulin

Insulin is a hormone made by the pancreas in the body that controls the glucose level in the blood. People who cannot make insulin in their bodies, or who make it but their body cannot use it properly, have the disease diabetes. When blood glucos ...

                                               

Ligand

A ligand is a biochemical substance. Its function is to bind to a biological molecule, and make the molecule perform a function. Ligand binding alters the shape of the receptor protein. This changes the proteins behaviour. In a narrower sense, it ...

                                               

Miller–Urey experiment

The Miller–Urey experiment was an experiment that made organic compounds out of Inorganic compounds by applying a form of energy. The idea was to simulate hypothetical conditions thought to be present on the early Earth Hadean or early Archaean. ...

                                               

Molecular biology

Molecular biology is the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly cell biology, genetics, biophysics and biochemistry. Molecular biology chiefly concerns itself with underst ...

                                               

Monosaccharide

Monosaccharides are the simplest form of carbohydrates. They consist of one sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose dextrose, fructos ...

                                               

Nitrogen fixation

Nitrogen fixation is the process by which nitrogen in the air is changed into ammonia or other nitrogenous compounds in the soil. Nitrogen fixation is essential to life because nitrogen compounds are needed for making all nitrogen-containing orga ...

                                               

Nucleotide

A nucleotide is an organic molecule. Nucleotides are the building blocks of the nucleic acids RNA and DNA. These two types of nucleic acid are essential biomolecules in all forms of life on Earth. A nucleotide is composed of a nucleobase nitrogen ...

                                               

Opsin

Opsins are the universal photoreceptor molecules of all visual systems in the animal kingdom. They change from a resting state to a signalling state by absorbing light. This activates the G protein, resulting in a signalling cascade which produce ...

                                               

Phosphorus cycle

The phosphorus cycle includes the following steps: The ocean bed eventually becomes a mountain range over several millions of years because of normal geological functions The phosphorus in those mountain ranges is washed off into bodies of water ...

                                               

Receptor (cell biology)

In cell biology, a receptor is a special structure that can be found in cell membranes. These are made of protein molecules such as glycoproteins. Receptors bind to specialised molecules. If the receptor has this molecule, it is activated, but if ...

                                               

Resting potential

The resting potential of a cell is the membrane potential that would be maintained if there were no action potentials, synaptic potentials, or other active changes in the membrane potential. In most cells the resting potential has a negative valu ...

                                               

RuBisCO

Ribulose-1.5-bisphosphate carboxylase oxygenase, better known as RuBisCO, is an enzyme that catalyzes the first major step of carbon fixation in the Calvin cycle. Carbon fixation is a process by which the atoms of atmospheric carbon dioxide are m ...

                                               

Substrate (biochemistry)

In biochemistry, a substrate is the molecule acted on by an enzyme to produce a product. p37 The general equation for an enzyme reaction is: Substrate + Enzyme –> Substrate:Enzyme –> Product:Enzyme –> Product + Enzyme An example: Sucrase ...

                                               

Sulfur cycle

The sulfur cycle is the way sulfur moves between rocks, waterways and living systems. Sulfur is an element important to ecosystems and the climate. The majority of sulfur is stored underground, for example under the ocean or in rocks. It also occ ...

                                               

Terpenoid

Turpenoids, or isoprenoids, are a large group of organic compounds. They are built of five-carbon isoprene units put together and modified in thousands of ways. They are lipids, and are found in all classes of living things. They are the largest ...

                                               

Plankton

Plankton are drifting organisms that live in the surface layers of the ocean. They live in the top layer of the ocean, called the epipelagic zone. They are not strong enough to swim against ocean currents. The term is in contrast to nekton, who c ...

                                               

Annual plant

In Botany, an annual plant is a plant that usually germinates, flowers and dies in one year. True annuals will only live longer than a year if they are prevented from setting seed. Some seedless plants can also be considered annuals even though t ...

                                               

Autotroph

Autotrophs are needed in every food chain in all ecosystems. They take energy from the environment sun light or inorganic sources and use it to make other organic molecules that are used to carry out various biological functions such as cell grow ...

                                               

Corm

A corm is a modified plant stem some plants use as a storage organ for hibernation. Corms are structurally plant stems, and can produce roots. On the top of the corm, one or a few buds grow into shoots that produce normal leaves and flowers. Some ...

                                               

Cultigen

A cultigen is a plant that is the result of artificial selection by humans. Liberty Hyde Bailey, an American botanist was the first to use the term, in 1918. Bailey noticed that the classification Linne introduced for plants was not useful for cl ...

                                               

Defence against herbivory

Defence against herbivory describes plant defences to avoid being eaten. There are many adaptations which improve the survival and reproduction of plants by reducing the impact of herbivores. Many plants produce chemicals which change the behavio ...

                                               

Germination

Germination occurs when a spore or seed starts to grow. It is a term used in botany. When a spore or seed germinates, it produces a shoot or seedling, or a hypha. The biology of spores is different from seeds. A spore germinates if and when condi ...

                                               

Honeydew

Honeydew is a liquid sugar that aphids and some scale insects make when they eat plant sap. Honeydew is very sticky. To eat plant sap, the aphid or scale insect pushes its mouth parts into the plant. Plant sap is under pressure inside the plant. ...

                                               

Mutation breeding

Mutation breeding or variation breeding is the process of exposing seeds to chemicals or radiation. This will increase the number of mutations in the seed. These seeds can then be crossed with other cultivars to get desirable traits. Plants creat ...

                                               

Pollen tube

The pollen tube is the tube through which sperm from the pollen reaches the egg cell, and fertilises the plant to form seeds. The pollen tube of most seed plants acts as a passageway. It transports sperm cells from the pollen grain, from the stig ...

                                               

Vegetation

Vegetation means the plant life of a region or the plant community. It means all ground cover by plants, and is the main element of the biosphere. When you say vegetation you do not think of any species composition, life forms, structure, spatial ...

                                               

Xerophyte

Xerophytes are plants which are adapted to dry/desert areas. They are a type of succulent plant. To survive these harsh conditions they have special features. For example, a cactus has white hairs which help to prevent water loss. Another example ...

                                               

Active transport

Active transport is when molecules move across a cell membrane from a lower concentration to a higher concentration. This takes energy, often from adenosine triphosphate. Active transport is done so cells get what they need, such as ions, glucose ...

                                               

Antibody

Antibodies are large Y-shaped proteins that can stick to the surface of bacteria and viruses. They are found in the blood or other body fluids of vertebrates. Antibodies are the key element in the adaptive immune system. The antibody recognizes a ...

                                               

Apoptosis

Apoptosis is the controlled death of a cell. It is an important part of tissue development. For example, during limb development in a foetus, apoptosis allows digits to separate from each other. The process is quite common until puberty begins. A ...

                                               

Autophagy

Autophagy, is one of the basic cell mechanisms. It allows the controlled breaking down of cell parts which do not work, or are not needed. The cell parts can then be recycled as required. There are several ways this happens. Targeted cell parts m ...

                                               

Theodor Boveri

Theodor Heinrich Boveri was a German biologist who made discoveries in cytology, embryology and genetics. His career was devoted to the processes whereby a new individual arises from parental reproductive materials. His work with sea urchins show ...

                                               

Cell differentiation

Cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. It is part of developmental biology. Different tissues have different kinds of organelles inside the cells. Differentiation occurs many ...

                                               

Cell growth

Cell growth is shorthand for the idea of "growth in cell populations" by means of cell reproduction. It is the stage which cells are preparing for the next division, biochemical activities and reactions are taking place, however no obvious change ...

                                               

Centromere

The centromere is a special region of a chromosome, usually near the middle. It is where the two identical sister chromatids stay in contact as the chromosome attaches to the spindle in mitosis. The region contains specific types of DNA, which ar ...

                                               

Clone

A clone is any cell or individual which is identical to another. In biology, cloning is the process of producing one or more genetically identical individuals. With whole individuals, it usually means the deliberate production of an identical cop ...

                                               

Cytokine

Cytokines are a group of signalling molecules made by cells. They help to control the immune system and fight disease. They are similar to hormones and, as we learn more about each, distinctions between the two are fading. Cytokines carry signals ...

                                               

Cytoskeleton

The cytoskeleton is a kind of scaffolding present in all cells. It is made of protein. It keeps cell shape, protects the cell and enables cells to move using structures such as flagella and cilia. It helps transport inside the cytoplasm the movem ...

                                               

Directed evolution

Directed evolution is a method used to produce enzymes for industrial or medical purposes. The method is protein engineering which mimics natural selection. The basic idea is to put a gene through repeated rounds of mutation, to make a library of ...

                                               

DNA

DNA, short for deoxyribonucleic acid, is the molecule that contains the genetic code of organisms. This includes animals, plants, protists, archaea and bacteria. DNA is in each cell in the organism and tells cells what proteins to make. Mostly, t ...

                                               

DNA methylation

DNA methylation is the main way gene activity is adjusted during life, especially during early development. It is a process by which methyl groups are added to DNA. This suppresses gene transcription. Two of DNAs four nucleotides, cytosine and ad ...

                                               

DNA replication

DNA replication is the process of copying a double-stranded DNA molecule. Both strands serve as templates for the reproduction of the opposite strand. The process is sometimes called "semi-conservative replication" because the new DNA from the or ...

                                               

Endosymbiosis

Endosymbiosis occurs when a symbiont lives inside the body or the cells of another organism. It is a very widespread phenomenon in living things. Examples are: Mycorrhiza: fungal hyphae and roots of trees. Single-celled algae inside reef-building ...

                                               

Epigenetics

Epigenetics is the study of changes in gene activity which are not caused by changes in the DNA sequence. It is the study of gene expression, the way genes bring about their phenotypic effects. These changes in gene activity may stay for the rema ...

                                               

Walther Flemming

Walther Flemming was a German biologist and a founder of cytogenetics. Making use of dyes he was able to find a structure which he named chromatin. He identified that chromatin was correlated to threadlike structures in the cell nucleus– the chro ...

                                               

Fusome

Fusome is a term from microbiology that describes a way different cells communicate with each other. Fusomes are simple openings, or pores, in the walls of certain types of cells. These allow certain chemical compounds to pass through.

                                               

Gene

Genes are forms of DNA. DNA is a collection of chemical information that carries the instructions for making the proteins a cell will need. Each gene contains a single set of instructions. These instructions usually code for a particular protein. ...

                                               

Gene expression

Gene expression is the process by which the heritable information in a gene, the sequence of DNA base pairs, is made into a functional gene product, such as protein or RNA. The basic idea is that DNA is transcribed into RNA, which is then transla ...