How can chromosomes be homologous

This is a type of genetic recombination that occurs during the formation of the egg and the sperm cells, and you'll recall formation of egg and sperm cells is called meiosis. During meiosis, what happens is that paired chromosomes from the male and the female parent align so that similar DNA sequences from the paired chromosomes have an opportunity to flip-flop, or to cross over one another.

That crossing over results in the shuffling of genetic material, much as the very gentle shuffling of a deck of cards would do. And it's important because it's one of the sources of genetic variation that we see among offspring of parents. Elaine A. Sex chromosomes can also suffer from nondisjunction. Turner syndrome is a form of monosomy that causes females to have only one X chromosome. Males with XYY syndrome have an extra Y sex chromosome in another example of trisomy.

Nondisjunction in sex chromosomes typically has less severe consequences than nondisjunction in autosomal chromosomes, but still impacts the quality of life for an individual. Chromosome mutations can affect both homologous and non-homologous chromosomes. A translocation mutation is a type of mutation in which a piece of one chromosome breaks off and is joined to another chromosome. Translocation mutation between non-homologous chromosomes is not to be confused with crossover between homologous chromosomes or regions of chromosomes.

Deletion, the loss of genetic material, and duplication, the over-copying of genetic material, are other common chromosome mutations. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile.

Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Regina Bailey. Biology Expert. Regina Bailey is a board-certified registered nurse, science writer and educator. Updated January 25, Featured Video. Cite this Article Format. Double-strand break formation is prepared but not immediately completed at the same sites. It is concluded that DNA-DNA interactions cannot bridge the distances between homologous chromosomes in the nucleus, and it is suggested that protein chains are formed between homologous segments.

These attach to homologous chains emanating from homologous sequences in other chromosomes, and the chains move along each other until the homologous DNA sequences meet.