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Synapsis vs. Crossing Over — What's the Difference?

By Tayyaba Rehman — Published on November 8, 2023
Synapsis involves homologous chromosomes pairing in meiosis; Crossing Over is the exchange of genetic material between non-sister chromatids during meiosis.
Synapsis vs. Crossing Over — What's the Difference?

Difference Between Synapsis and Crossing Over


Key Differences

Synapsis is a pivotal phase during prophase I of meiosis, where homologous chromosomes meticulously align with each other. On the other hand, Crossing Over is a subsequent phenomenon, occurring post-synapsis, which involves the exchange of genetic material between non-sister chromatids.
During Synapsis, the intimate alignment allows chromosomes to form a structure known as a tetrad, which is crucial for genetic variation. Conversely, during Crossing Over, chromatids physically exchange segments, fostering genetic diversity by creating new combinations of genetic information.
Synapsis is fundamentally about the coming together of homologous chromosomes, facilitating an environment wherein genetic recombination, facilitated through Crossing Over, can transpire. Crossing Over, conversely, allows segments of genetic material to be swapped, thereby providing an assortment of genetic possibilities in gametes.
In Synapsis, the juxtaposition of homologous chromosomes is critical for ensuing cellular processes during meiosis. Conversely, Crossing Over, which introduces genetic variation, is crucial in preventing the inheritance of identical chromosomal combinations from parents.
Lastly, while Synapsis creates a requisite framework for chromosomes to interact and bind, Crossing Over specifically propels genetic divergence, ensuring that offspring acquire a unique set of genetic information, fostering variation within a species.

Comparison Chart


Pairing of homologous chromosomes
Exchange of genetic segments


Prophase I of meiosis
Post-synapsis in prophase I of meiosis


Formation of tetrads
New combinations of genetic material

Genetic Variation

Facilitates an environment for variation
Directly generates genetic variation

Biological Importance

Essential for accurate segregation of chromosomes
Ensures genetic diversity among offspring

Compare with Definitions


Synapsis occurs during prophase I of meiosis.
Synapsis is a preliminary, essential phase within meiotic prophase I.

Crossing Over

Crossing Over involves swapping genetic segments.
Crossing Over reshuffles genetic information, creating diverse gametes.


Synapsis is the pairing of homologous chromosomes.
During synapsis, homologous chromosomes align closely in meiosis.

Crossing Over

Crossing Over enhances genetic variation.
Through Crossing Over, offspring inherit a novel genetic combination.


Synapsis allows the formation of tetrads.
Synapsis enables the chromosomes to form tetrads by aligning together.

Crossing Over

Crossing Over happens during meiotic prophase I.
Post-synapsis, during prophase I, Crossing Over occurs between chromatids.


Synapsis sets the stage for Crossing Over.
Synapsis aligns chromosomes, preparing them for potential Crossing Over.

Crossing Over

Crossing Over affects resultant gametes.
Gametes acquire new genetic combinations due to Crossing Over.


Synapsis ensures orderly chromosome segregation.
Without synapsis, chromosomes might not segregate accurately in meiosis.

Crossing Over

Crossing Over occurs between non-sister chromatids.
Crossing Over involves the exchange of genetic sections among chromatids.


The side-by-side association of homologous chromosomes during the first prophase of meiosis.

Crossing Over

The exchange of genetic material between homologous chromosomes that occurs during meiosis and contributes to genetic variability.


The association of homologous maternal and paternal chromosomes during the initial part of meiosis.


Alternative form of synapse


The side by side pairing of homologous maternal and paternal chromosomes at the start of meiosis

Common Curiosities

Does Synapsis contribute to genetic variation?

Indirectly, as synapsis sets the stage for Crossing Over, which generates variation.

Why is Crossing Over crucial for species?

It introduces genetic variation, crucial for adaptation and evolution.

Can Crossing Over occur without Synapsis?

Unlikely, as synapsis ensures the precise alignment needed for Crossing Over.

What’s the essential distinction between Synapsis and Crossing Over?

Synapsis is the pairing of chromosomes; Crossing Over is the genetic exchange between them.

Does Synapsis involve genetic exchange?

No, synapsis involves alignment, not exchange; Crossing Over involves exchange.

What biological structure forms during Synapsis?

A tetrad, which is a pair of homologous chromosomes aligned together.

Does Synapsis impact resultant gametes?

Yes, by facilitating Crossing Over, it indirectly affects gamete composition.

How does Crossing Over affect offspring?

It grants them a unique genetic combination, differing from their parents.

Is Crossing Over a predictable event?

No, it happens at varied locations, producing unique genetic outcomes.

What chromosomes partake in Crossing Over?

Non-sister chromatids of homologous chromosomes participate.

Is Crossing Over a source of genetic diversity?

Yes, it produces new genetic combinations, enhancing diversity.

Can Synapsis be observed microscopically?

Yes, during prophase I, tetrads formed during synapsis are visible.

What phase follows the occurrence of Crossing Over?

Metaphase I follows, where tetrads align at the metaphase plate.

Is Synapsis a phase in mitosis?

No, synapsis specifically occurs during meiosis, not mitosis.

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Author Spotlight

Written by
Tayyaba Rehman
Tayyaba Rehman is a distinguished writer, currently serving as a primary contributor to As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.

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