What is a homologous chromosome? The genetic material (DNA) of each living cell is encased into coiled structures called chromosomes, whether animal, plant, or bacterial.
Chromosomes are only visible when a cell is dividing, despite the fact that they are known to be found in the nucleus. During this procedure, the majority of what was learned about chromosomes came from studying them.
Yet, have you ever heard of “homologous chromosomes” or been perplexed by it? Examine the structure and function of these comparable chromosomes throughout various phases of cell division and cycle.
What is a Homologous Chromosome?
Pairs of chromosomes that come from each parent are referred to as homologues, or similar chromosomes. The length and quantity of genes, as well as the banding pattern, position of genes, and position of centromeres are all identical in both animals.
- These come from distinct alleles, indicating that the genes may or may not be alternative versions of one another; despite having many traits in common.
- Basically, diploid organisms, like humans, have two pairs of homologous chromosomes that are inherited from the mother and father.
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The twinning and fusion of homologous chromosomes during this stage is known as sister chromatids. The replicated chromosomes that are connected together in a place called centromere are known as sister chromatids.
- During anaphase, the sister chromatids split apart on opposing poles, and then between daughter cells during mitosis.
During meiosis, the behavior of sister chromatids is somewhat different. The sister chromatids pair into tetrads during this phase, which are homologous chromosomes. In a process known as recombination, the homologous chromosomes swap some of their genetic material during this time.
- The variety in genes is generated by this genetic recombination. During meiosis I, the homologous chromosomes are separated, and during meiosis II, the sister chromatids.
- The progeny cells, which have half the number of chromosomes than their parent cells, are four in number.
When chromosomes attempt to split during anaphase (whether mitosis or meiosis), nondisjuntion refers to the mistake. Either insufficient or too many chromosomes may result from the fertilization of cells harbouring defective chromosomes.
- When nondisjunction happens, it may cause genetic abnormalities that lead to physical flaws, making it a problem for organisms.
- If nondisjunction occurs during mitosis, the organism will create an immature embryo with the incorrect number of chromosomes.
- The homologous chromosomes will fail to separate if nondisjunction occurs during meiosis I, whereas the sister chromosomes will fail to do so if it occurs during meiosis II. The mutation may be inherited in both situations.
HUMANS GENERALLY HAVE 46 CHROMOSOMES (2N), WITH THE FIRST 22 PAIRS BEING THE AUTOSOMES AND THE LAST ONE BEING THE SEX CHROMOSOMES X AND Y. WITH THAT SAID, CAN YOU GIVE ANY IMPORTANCE OF HOMOLOGOUS CHROMOSOMES TO US?