Genetic Coupling
Genetic Coupling - Related Videos
16:16
Genetically-encoded Molecular Probes to Study G Protein-coupled Receptors
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Cited by 15 •
2013
We genetically-encode the unnatural amino acid, p-azido-L-phenylalanine at various targeted positions in GPCRs and show the versatility of the azido group in different applications. These include a targeted photocrosslinking technology to identify residues in the ligand-binding pocket of a GPCR, and site-specific bioorthogonal modification of GPCRs with a peptide-epitope tag or fluorescent probe.
08:50
Genetic Screens
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2023
Genetic screens are critical tools for defining gene function and understanding gene interactions. Screens typically involve mutating genes and then assessing the affected organisms for phenotypes of interest. The process can be “forward”, where mutations are generated randomly to identify unknown genes responsible for the phenotypes, or it can be “reverse”, where specific genes are targeted for mutation to observe what phenotypes are produced.Here, JoVE reviews various types of genetic...
01:20
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
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2024
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others. The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:22
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
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2024
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive. The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
07:34
FISH for Pre-implantation Genetic Diagnosis
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Cited by 17 •
2011
This article describes the selection of suitable probes for single-cell FISH, spreading techniques for blastomere nuclei, and in situ hybridization and signal scoring, applied to pre-implantation genetic diagnosis (PGD) in a clinical setting.
FAQs
Crossing over can exchange corresponding chromosome segments during meiosis, separating alleles that were previously carried on the same homolog. The closer two loci are physically located, the less likely an exchange will occur between them in a given meiotic event. Consequently, tightly associated loci produce fewer recombinant allele combinations than loci separated by greater chromosomal distances.
Recombination frequency measures how often meiotic products contain allele combinations that differ from the original parental combinations. A lower frequency indicates stronger linkage and a shorter estimated distance, whereas a higher frequency indicates more frequent separation and a greater estimated distance. This relationship allows geneticists to convert inheritance observations into relative positions on linkage maps.
Coupling phase identifies a configuration in which favorable alleles at different loci occur on the same homolog. That arrangement establishes the parental allele combinations against which recombinant combinations are evaluated. Recognizing the phase helps investigators interpret inheritance data correctly, distinguish preserved combinations from those produced by crossing over, and relate allele patterns to biological traits.
The principal factor is the physical separation between loci on the chromosome, because that distance influences the chance that crossing over will occur between them. Closely positioned loci are more likely to remain associated, while more widely separated loci are more likely to yield recombinant combinations. The observed pattern therefore reflects both chromosome organization and meiotic recombination.
Researchers compare allele combinations inherited together with combinations produced after recombination. They calculate recombination frequencies for pairs of loci and use those estimates to arrange loci according to their relative chromosomal distances. Repeating the comparison across multiple loci produces a linkage map, which represents genomic organization through inheritance patterns rather than direct physical observation.
A disease-associated variant can be followed through inheritance by examining whether it remains associated with nearby alleles in affected and unaffected individuals. Strong association suggests limited separation by crossing over and can help identify a genomic region linked to the trait. This approach supports inheritance analysis and helps connect genetic variation with disease-related biological outcomes.
Linkage patterns can connect inherited genetic variation with changes in protein structure, metabolism, or cellular function. By tracking alleles that occur together, investigators can examine whether a genomic region is associated with a biochemical phenotype and then interpret that relationship in molecular terms. The approach therefore links chromosome-level inheritance analysis with functional questions in biochemistry.