Abiogenesis
... is primarily used in the context of biology
and the origin of life .
Some confusion exists on ... Generatio primaria, archegenesis, autogenesis,
and archebiosis ), was the theory according to which ... explicitly taught this form of abiogenesis,
and laid it down as an observed fact that some ...
Absorption spectrum
... the electron does not stay in its higher orbit
and falls back down, emitting a photon of exactly the ... shown are particular to particular elements,
and allows for identification of elements present in stars
and other gaseous objects that cannot be measured ...
Coenzyme A
... , or HSCoA ) is adapted from pantothenic acid
and adenosine triphosphate
and used in metabolism in areas such as fatty acid oxidization
and the citric acid cycle . Its main function is to ...
Actin
... enable cell movements (through pseudopods );
and participate in certain cell junctions, in cytoplasmic streaming
and in contraction of the cell during cytokinesis . ... to ADP . An ATP-actin complex polymerizes faster
and dissociates slower than an ADP-actin complex. ...
Acrosome
... digestive enzymes (including hyaluronidase
and acrosin ) needed to penetrate the zona ... fuses with the plasma membrane of the egg cell,
and digestive enzymes are released from the sperm to digest the zona pellucida
and give access to the egg.
See also
...
Acrosome
... digestive enzymes (including hyaluronidase
and acrosin ) needed to penetrate the zona ... fuses with the plasma membrane of the egg cell,
and digestive enzymes are released from the sperm to digest the zona pellucida
and give access to the egg.
See also
...
Activation energy
... they must collide in the correct orientation
and possess a certain minimum amount of energy. As ... repel. This requires energy - activation energy -
and comes from the heat of the system, i.e. the translational , vibrational ,
and rotational energy of each molecule . If there ...
Active site
... site where catalysis occurs. The structure
and chemical properties of the active site allow the recognition
and binding of the substrate .
The active site in ... enzyme at another site, the allosteric site ,
and this causes a structural change in the enzyme ...
Active transport
... is the mediated transport of biochemicals ,
and other atomic / molecular substances, across ...
Types
There are two main types, primary
and secondary . In primary transport energy is ... forms of this are counter-transport (antiport)
and co-transport (symport).
Counter-transport
...
Adaptive radiation
... is an evolutionary process driven by mutation
and natural selection .
Adaptive radiation often ... adapted to the new environment. The rise
and fall of new species is now progressing very ... of an environmental change is the rapid spread
and development of mammalian species after the ...
Adenosine triphosphate
... energy transfer; that is, ATP is able to store
and transport chemical energy within cells . ATP ...
Chemically, ATP consists of adenosine
and three phosphate groups. It has the empirical formula C 10 H 16 N 5 O 13 P 3 ,
and the chemical formula C 10 H 8 N 4 O 2 NH 2 (OH) 2 ...
Albinism
... in a lack of pigmentation in the eyes, skin
and hair. It is an inherited condition arising from ... of problems with photosensitivity in eyesight
and skin usually result from the condition. This ... lack this protective pigment in their skin,
and can burn easily from exposure to the sun as a ...
Affinity chromatography
... This method is usually used to:
Purify
and concentrate a molecule from a mixture into a ... The molecule of interest will have a well known
and defined property which can be exploited during ... can then be removed from the mixture, washed
and the target molecule released from the entrapment ...
Alcohol
... to ethanol , also known as grain alcohol ,
and often to any beverage that contains ethanol (see ...
1 Structure
1.1 Primary, Secondary,
and Tertiary Alcohols
1.2 Methanol
and ethanol
2 Other common alcohols
3 ...
Albumin
... plasma protein that is produced in the liver
and forms a large proportion of all plasma protein. ... in human blood is 3.5 to 5.0 g/dL,
and albumin normally constitutes about 60% of plasma ... In nephrotic syndrome, this property is lost,
and there is more albumin loss in the urine.
...
Alexander Fleming
... ) discovered the antibiotic substance lysozyme
and isolated the antibiotic substance penicillin ... a farm at Lochfield in Ayrshire , Scotland
and was schooled for two years at the Academy in ... He inspected each specimen before discarding it
and noticed an interesting fungal colony had grown ...
Allele
... homologous chromosomes in their somatic cells ,
and thus contain two copies of each gene. An organism ... be heterozygous . Often one allele is "dominant"
and the other is "recessive" - the "dominant" allele ... allele, in a heterozygous flower (with one red
and one white allele), the petals will be red. The ...
Alfred Russel Wallace
... naturalist , geographer , anthropologist
and biologist . Wallace's independent proposal of a ... Charles Darwin to reveal his own more developed
and researched, but unpublished, theory sooner than ...
1 Early life
2 Exploration
and study of the natural world
3 Theory of ...
Allostery
... typical scenario in which an enzyme's allosteric
and active sites are distinct.
Contents ... (MWC) model put forth by Monod , Wyman,
and Changeux, or by the sequential model described by Koshland, Nemethy,
and Filmer. Both postulate that enzyme subunits exist ...
Alga
... They are generally regarded as simple plants ,
and some are related to the higher plants . Others ... All algae lack true leaves , roots , flowers ,
and other tissue structures found in higher plants. They are distinguished from bacteria
and protozoa in that they are photoautotrophic . ...
Allele frequency
... species, which contain two sets of chromosomes)
and finally d) a variant or allele of the gene, ... the allele (i.e. carry one copy of that allele
and one copy of another in each somatic cell)
and 4% will be homozygous (carrying two copies of ...
Allostery
... typical scenario in which an enzyme's allosteric
and active sites are distinct.
Contents ... (MWC) model put forth by Monod , Wyman,
and Changeux, or by the sequential model described by Koshland, Nemethy,
and Filmer. Both postulate that enzyme subunits exist ...
Alpha helix
... postulated by Linus Pauling , Robert Corey ,
and Herman Branson in 1951 based on the known crystal structures of amino acids
and peptides
and Pauling's prediction of planar peptide bonds .
...
Alternative splicing
... can lead to different ripe mRNA molecules
and therefore to different proteins. Also viruses ... from the DNA , it includes several introns
and exons . In nematodes , the mean is 4-5 exons
and introns; in the fruit fly Drosophila there ...
Amine
... Category:Amines for a list of types of amine
and some real examples of this class of chemical.
... used to label these groups to differentiate them
and show that they may be different (or they could be ... -10 M
Like ammonia, amines act as bases
and are reasonably strong (see table for examples of ...
Anabolism
... processes tend toward "building up" organs
and tissues. These processes produce growth
and differentiation of cells
and increase in body size, a process that involves ...
Amino acid
... is any molecule that contains both amino
and carboxylic acid functional groups .
In biochemistry , this shorter
and more general term is frequently used to refer to ... amino acids: those amino acids in which the amino
and carboxylate functionalities are attached to the ...
Anatomy
... branch of biology that deals with the structure
and organization of living things; thus there is animal anatomy ( zootomy )
and plant anatomy ( phytonomy ).
The major branches of anatomy include comparative anatomy
and human anatomy .
Animal anatomy may include the ...
AMP
... an audio decoding engine made by Tomislav Uzelac
and others, which stood at the basis of or inspired:
... (formerly FreeAMP )
A brand of electrical
and electronic connectors , part of Tyco ... company providing insurance , investment
and other financial services.
...
Animal
... they are multicellular , capable of locomotion
and responsive to their environment,
and feed by consuming other organisms. Their body ... divided the living world between animals
and plants ...
Anaphase
... Anaphase ( Greek : ανά = up
and φάσις = stage) is the ... is a protein complex called the kinetochore,
and these fibres are sometimes referred to as ... metaphase (M-phase) activity by cleaving
and inactivating the M-phase cyclin required for the ...
Andrew Huxley
... , England , UK ) is a British physiologist
and biophysicist , who won the 1963 Nobel Prize ... by a central nervous system . Hodgkin
and Huxley shared the prize that year with John ... who was cited for research on synapses . Hodgkin
and Huxley's findings led the pair to hypothesize ...
Antibiotic
... which also includes anti-viral, anti-fungal,
and anti-parasitic drugs. They are relatively harmless to the host,
and therefore can be used to treat infections . ... with a molecular weight less than 2000
and they are not enzymes .
Unlike previous ...
Antibiotic resistance
... of broad-spectrum antibiotics , such as second
and third generation cephalosporins , greatly ... improper use of antibiotics by patients,
and the use of antibiotics as livestock food ... pathogens. Found on the mucous membranes
and the skin of around a third of the population, ...
Antibody
... protein used by the immune system to identify
and neutralize foreign objects like bacteria
and viruses . Each antibody recognizes a specific ... as antibodies. They are found in the blood
and tissue fluids, as well as many secretions . ...
Antigen
... to the host, molecular size, chemical composition
and heterogeneity (e.g. different amino acids in a ... molecule . Depending on the antigen presented
and the histocompatibility molecule used, several ... into the antigen presenting cells (APCs),
and degraded into fragments. The fragments are then ...
Anton van Leeuwenhoek
... , 1632 - August 26 , 1723 ) was a tradesman
and scientist from Delft , in the Netherlands . ... contribution to improvement of the microscope
and his contributions towards the establishment of ... microscope he was the first to observe
and describe muscle fibres, bacteria , ...
Antigenic shift
... all types of influenza including influenza A, B
and C. Antigenic shift, however, occurs only in ... humans. Affected species include other mammals
and birds, giving influenza A the opportunity for a ... reorganization of surface antigens. Influenza B
and C only infect humans, minimizing the chance to ...
Apoptosis
... apoptosis (from the Greek words apo = from
and ptosis = falling, pronounced ap-a-tow'-sis ... facilitates the safe disposal of cell corpses
and fragments.
Since the beginning of the 1990s, ... the characteristic shapes (the morphology )
and sequences of apoptosis, but all types of PCD are ...
Arabidopsis
... are small flowering plants related to cabbage
and mustard .
One species, Thale Cress ( ... for studying plant sciences, including genetics
and plant development. Similarly as mouse
and fruit fly ( Drosophila ) are used as model ...