Transition Mutation
Transition Mutation - Related Videos
02:31
Phase Transitions
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2020
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to occupy...
00:36
Viral Mutations
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2019
A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material for adaptive...
02:58
Properties of Transition Metals
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2020
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals. Figure 1: Periodic Table. The transition metals are located in groups 3–11 of the periodic table. The inner transition metals are in the two rows...
01:58
Cooperative Allosteric Transitions
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2020
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
02:27
Mutations
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2020
Mutations are changes in the sequence of DNA. These changes can occur spontaneously during DNA replication or be induced by environmental factors. Mutations can be characterized in several ways: by whether and how they alter the amino acid sequence of the protein, by the scale of the DNA affected, and by whether they affect somatic or germline cells.Consequences of Point Mutations at the Molecular LevelMutations that affect a single nucleotide are called point mutations. When point mutations...
FAQs
Several molecular events can create the altered base pairing that precedes fixation. Replication errors may insert an incorrect partner, while tautomeric shifts temporarily change a base’s pairing behavior. Deamination can also modify a base and promote mispairing. If repair corrects the lesion before replication, the change need not persist; failure to repair allows the altered sequence to become permanent.
The biological consequence depends strongly on where the substitution occurs and which codon is affected. A synonymous change leaves the encoded amino acid unchanged, whereas a missense change alters it. A nonsense change instead creates a signal associated with termination. Thus, the same mutation category can range from no detectable effect to a change in protein function.
DNA repair determines whether a chemically altered or incorrectly paired base remains transient or becomes part of the DNA sequence. Repair must act before replication copies the altered information. When that correction fails, replication can fix the change in the sequence, making it available for later analysis as a mutation rather than a temporary lesion.
Researchers examine transition mutations in genetic disease studies to connect sequence changes with possible molecular consequences. The key interpretation requires more than recording the substitution: its position and codon context help indicate whether it is synonymous, missense, or nonsense. This approach distinguishes changes with no detectable effect from those that may influence protein function.
In mutation-rate measurements, researchers can analyze how frequently transition patterns occur within the sequences under study. Such measurements do not depend only on naming the base change; they also require attention to the mechanisms that generate it, including replication errors, tautomeric shifts, and deamination. The resulting pattern contributes to quantitative study of mutation occurrence.
Transition patterns are also examined in phylogenetics and molecular evolution because sequence changes can be compared across biological lineages. Researchers can evaluate where these substitutions occur and how their codon consequences may affect interpretation. This makes the mutation category useful for connecting individual base changes with broader analyses of evolutionary sequence change.