Main distinction – Synapsis vs cross Over

Synapsis and also crossing over space two occasions that occur throughout the chromosome segregation in meiosis 1. Meiosis occurs during the production of gametes in order to attain the sexual reproduction that organisms. Both synapsis and crossing over are vital in exerting hereditary variation amongst the individuals by permitting the exchange of hereditary material between homologous chromosomes. The main difference between synapsis and also crossing over is the synapsis is the pairing the homologous chromosomes throughout the prophase 1 of the meiosis 1 vice versa, crossing end is the exchange that the genetic material throughout synapsis.

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1. What is Synapsis – Definition, Mechanism, Function, Characteristics 2. What is crossing Over – Definition, Mechanism, Function, Characteristics 3. What is the difference in between Synapsis and Crossing Over


What is Synapsis

The pairing that the 2 homologous chromosomes throughout the meiosis is known as synapsis. The synapsis occurs at prophase 1 the meiosis 1. It allows the two homologous chromosomes to segregate in ~ the anaphase 1 that meiosis 1.

Mechanism that Synapsis

During synapsis, the end of the separation, personal, instance chromosomes room attached come the nuclear envelope first. This chromosomal end-membrane complexes are moved until they find the various other homologue to pair v the assistance of the extranuclear cytoskeleton. Then, the intervening areas of the two chromosomes are associated by synaptonemal complexes, which consist the RNA and also proteins. A synaptonemal complex is displayed in figure 1.


Figure 1: Synaptonemal facility (SC)(A) Lateral view: homologous chromosomes (light blue rods) aligned together by the meshwork that transverse (black lines) and longitudinal (dark blue rods) filaments. (B) Tomato SCs in ~ the top and also two tomato SCs (Crossing over occurs in ~ the marked sites.)

Autosomes form two synaptonemal complexes in ~ the two ends the the chromosome. But, sex chromosomes form a single synaptonemal complex at one end of every chromosome.

Function the Synapsis

The significant role of synapsis is the recognition of the 2 homologues by pairing, in stimulate to experience a effective synapsis. During synapsis, genetic variation is permitted in two ways. Very first is the elevation orientation that the pairs of the homologous chromosomes in the cabinet equator. This is called the law of independent assortment, which enables the segregation of maternal and also paternal chromosomes in a arbitrarily nature. Secondly, the chromosomal cross-over in ~ chiasmata that non-sister chromatids allows the hereditary recombination of chromosomes come occur, resulting in brand-new combinations that alleles in the inherited chromosomes. DNA repair wake up in response to DNA damage, especially double-strand breaks during synapsis.

What is crossing Over

The exchange the DNA pieces in between non-sister chromatids during the synapsis is recognized as crossing over. Thus, chromosomal crossing over occurs during the prophase 1 the meiosis 1 in the sexual reproduction.

Mechanism of cross Over

Crossing over occurs as soon as breaking under of comparable DNA areas occurs in ~ the homologous chromosome pair, causing the genetic recombination. Non-sister chromatids in this corresponding DNA regions intertwine first, breaking apart the similar DNA regions. This similar DNA regions are exchanged v crossing over. The chiasma is one X choose region, whereby the two non-sister chromatids space joined together throughout crossing over. The development of the chiasma stabilizes the bivalents or the chromosomes throughout their segregation at the metaphase 1. The process of crossing end is shown in figure 2.


Figure 2: crossing Over

Synthesis-dependent strand annealing (SDSA) is another form of recombination the occurs during synapsis, which allows the exchange that information, but not the physical exchange that DNA pieces.

Function of crossing Over

Crossing over rises the hereditary variation in ~ an offspring. The genetic variation exerted by cross over gives a defense versus the procedure called chromosome killer. The recurring crossing over enables the genes in that areas to concentration independently. The concentration of beneficial genes would certainly be an benefit towards the species.

Difference between Synapsis and also Crossing Over


Synapsis: The pairing the the homologous chromosomes during the prophase 1 that the meiosis 1 is known as the synapsis.

Crossing Over: The exchange the the hereditary material during synapsis is well-known as the cross over.


Synapsis: Synapsis occurs at first.

Crossing Over: Synapsis is adhered to by crossing over.


Synapsis: Synapsis constantly occurs.

Crossing Over: Crossing over may occur sometimes.


Synapsis: Synapsis guarantee the suitable segregation of homologous chromosomes and allows the recombination through crossing over.

Crossing Over: crossing over enables the variations of alleles in a populace through genetic recombination.


Synapsis: two homologous chromosomes come together throughout synapsis.

Crossing Over: DNA piece of the non-sister chromatids room exchanged throughout crossing over.

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Synapsis and crossing end occurs during the prophase 1 of meiosis 1, which is affiliated in the sexual reproduction that organisms. Synapsis is the pairing that homologous chromosomes in a cell. The 2 chromosomes are organized together through synaptonemal complexes, i beg your pardon are created by a repertoire of RNA with proteins. Chiasma is the place where the 2 non-sister chromatids are hosted together during synapsis. It is an X-shaped DNA region, which enables the double-strand break of both non-sister chromatids, trading the hereditary material between the 2 non-sister chromatids. This type of exchanges in genetic material are recognized as recombination. Genetic variation is make up among the offspring through recombination. The main difference between synapsis and also crossing over is your correspondence along with the function.

Reference: 1. “Synapsis.” Wikipedia. Wikimedia Foundation, 18 Feb. 2017. Web. 15 Mar. 2017. 2. “Chromosomal crossover.” Wikipedia. Wikimedia Foundation, 13 Mar. 2017. Web. 15 Mar. 2017.

Image Courtesy:1. “Synaptonemal complex” through Images and legend courtesy the Daniel G. Peterson, Mississippi Genome exploration Laboratory, Mississippi State University, Mississippi State, Mississippi, unified States. (CC by 2.5) via Commons Wikimedia2. “Cross-over” (Public Domain) via Commons Wikimedia