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A pair of homologous chromosomes, or homologs, is a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci , where they provide points along each chromosome that enable a pair of chromosomes to align correctly with each other before ...
Homologous somatic pairing. Dynamic chromosome pairing. The term “pairing” describes the spatial juxtaposition of entire homologous chromosomes, allelic sequences, and/or homologous sequences at non-allelic locations. (A, B) Homologous chromosomes can exist as paired throughout their entire length and the relative activities of pairing and ...
A chromosome is a package of DNA with part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome -forming packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA ...
The independent orientation of homologous chromosome pairs along the metaphase plate during metaphase I and orientation of sister chromatids in metaphase II, this is the subsequent separation of homologs and sister chromatids during anaphase I and II, it allows a random and independent distribution of chromosomes to each daughter cell (and ...
Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes ' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called ...
Chromatid pairs are normally genetically identical, and said to be homozygous. However, if mutations occur, they will present slight differences, in which case they are heterozygous . The pairing of chromatids should not be confused with the ploidy of an organism, which is the number of homologous versions of a chromosome.
Synapsis or Syzygy is the pairing of two chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis. When homologous chromosomes synapse, their ends are first attached to the nuclear envelope.
Chromosomal changes during the cell cycle are displayed at top center. The mitochondrial genome is shown to scale at bottom left. The human genome is a complete set of nucleic acid sequences for humans, encoded as the DNA within each of the 24 distinct chromosomes in the cell nucleus. A small DNA molecule is found within individual mitochondria.