Transition

transition mutation
a base pair substitution in which the orientation of the purine and pyrimidine bases on each DNA strand remain the same; i.e., AT to GC, TA to GC ...
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Transitional Vertebrate Fossils FAQ
[Last Update: March 17, 1997]
wrote this FAQ as a reference for answering the "there aren't any transitional fossils" statement that pops up on talk.origins several times each year.
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In a chemical reaction, an unstable and high-energy configuration assumed by reactants on the way to making products. Enzymes are thought to bind and stabilize the transition state, ...
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CATALYZING CAREER TRANSITIONS TO COMPUTATIONAL MOLECULAR BIOLOGY
POSTDOCTORAL FELLOWSHIPS IN COMPUTATIONAL MOLECULAR BIOLOGY
(second announcement) ...
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The mitochondrial permeability transition (mPT) involves the opening of a non-specific pore in the inner membrane of mitochondria, converting them from organelles whose production of ATP sustains the cell, to instruments of death.
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Transition
The term proposed by Freese (1959) for a mutation caused by the substitution in DNA or RNA of one purine by the other, and similarly with the pyrimidines. (Cf. transversion.)
Related Terms: Mutation ...
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Transition in the species composition of a biological community, often following ecological disturbance of the community; the establishment of a biological community in an area virtually barren of life.
ecology
[Gk. oikos, home + logos, a discourse] ...
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Transition states
Fig-1 demonstrates the relationship between activation energy (
Ea
) and enthalpy of formation ("H) with and without a catalyst. The highest energy position (peak position) represents the transition state.
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Transition vesicles pinch off from the surface of the endoplasmic reticulum carrying
integral membrane proteins
soluble proteins awaiting processing
processing enzymes ...
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Transition mutation
A base substitution mutation where a purine is replaced by a different purine, or a pyrimidine is replaced by a different pyrimidine.
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transition reaction Biochemical process of converting 3-carbon pyruvate into 2-carbon acetyl and attaching it to coenzyme A (CoA) so it can enter Kreb's cycle. Carbon dioxide is also released and NADH is formed (from NAD and H) in this process.
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transition state - structure that forms transiently in the course of a chemical reaction and has the highest free energy of any reaction intermediate; a rate-limiting step in the
reaction.
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transitional mutants A type of mutation in which a single purine-pyrimidine base pair is replaced by another.
transitional zone A zone in which populations from two or more adjacent communities meet and overlap.
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Transition: A nucleotide substitution in which one pyrimidine is replaced by the other pyrimidine, or one purine replaced by the other purine (e.g., A is changed to G, or C is changed to T) (contrast with Transversion) .
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The transition state in a reaction is the point at which the original bonds have stretched to their limit. Transition states are only in existence for extremely brief (10-15 s) periods of time.
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The transition from the Medieval Warm Period to the Little Ice Age
Beginning of the Ottoman Empire, early expansion into the Balkans
The Avignon papacy transfers the seat of the Popes from Italy to France ...
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The transition to modern humans is one that people argue about. Did it happen subsequent to that time? Did it happen over a broad front? Did it happen to one group of individuals or one small tribe, who then became modern humans?
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An antibody selected for its ability to catalyze a chemical reaction by binding to and stabilizing the transition state intermediate. Catalytic RNA (ribozyme). A natural or synthetic RNA molecule that cuts an RNA substrate. Cation.
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activation energy (DGo') The amount of energy (SI unit of joules) required to convert 1 mole of a reactant from the ground state to the transition state.
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Substitution mutations from one pyrimidine to another or one purine to another (horizontals in diagram) are called transitions. Mutations from a pyrimidine to a purine, or the reverse (verticals and diagonals in diagram), are called transversions.
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Redox-potential discontinuity. That depth below the sediment-water interface marking the transition from chemically oxidative to reducing processes
Red tide. A dense outburst of phytoplankton (usually dinoflagellates) often coloring water red brown ...
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