What is unequal homologous recombination?
Unequal crossing over is a type of gene duplication or deletion event that deletes a sequence in one strand and replaces it with a duplication from its sister chromatid in mitosis or from its homologous chromosome during meiosis. Normally genes are responsible for occurrence of crossing over.
What is double homologous recombination?
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may be also RNA in viruses).
What is the function of Spo11?
Spo11 is a protein that in humans is encoded by the SPO11 gene. Spo11, in a complex with mTopVIB, creates double strand breaks to initiate meiotic recombination. Its active site contains a tyrosine which ligates and dissociates with DNA to promote break formation.
Why does homologous recombination occur in meiosis?
Homologous recombination is a type of genetic recombination that occurs during meiosis (the formation of egg and sperm cells). Paired chromosomes from the male and female parent align so that similar DNA sequences from the paired chromosomes cross over each other.
Which of the following is a consequence of unequal crossing over during meiosis?
Unequal crossing over (during meiosis in a woman) involving these two loci can result in an egg with an X chromosome that is missing one of the genes or has an extra of one of the genes (fig. 8.17b). Also, one or more of the genes might be “chimeric”, if the cross-over occurred in the interior region of the genes.
What phase does homologous recombination occur in meiosis?
prophase I
During prophase I, the pairs of homologous chromosomes come together to form a tetrad or bivalent, which contains four chromatids. Recombination can occur between any two chromatids within this tetrad structure.
What is SPO11 gene?
SPO11 (SPO11 Initiator Of Meiotic Double Stranded Breaks) is a Protein Coding gene. Diseases associated with SPO11 include Male Infertility and Ectodermal Dysplasia 1, Hypohidrotic, X-Linked. Among its related pathways are Cell Cycle, Mitotic and Meiosis.
What stage of meiosis does homologous recombination occur?
Recombination in meiosis. Recombination occurs when two molecules of DNA exchange pieces of their genetic material with each other. One of the most notable examples of recombination takes place during meiosis (specifically, during prophase I), when homologous chromosomes line up in pairs and swap segments of DNA.
Why can crossing over recombination only occur during prophase I of meiosis?
Crossing over (recombination) only occurs during Prophase 1 of Meiosis because at this point homologous chromosomes line up at the centre of the cell. Thus, the aligned chromosomes are able to have their legs intertwine with that of the chromosome beside them, in order for crossing over to occur.
