Difference Between Gene Conversion and Crossover

Thekey differencebetween gene conversion and crossover is thatgene conversion involves the unidirectional transfer of genetic material from a donor sequence to an acceptor sequence, while crossover is the exchange of genetic material during the sexual reproduction between twohomologous chromosomes’nonsister chromatids.

基因转换和交叉两种机制of homologousrecombination. Gene conversion is unidirectional. In gene conversion, the donor sequence remains physically unchanged. Crossover occurs in both directions. Crossing over happens during sexual reproduction when forming gametes. This mechanism involves the exchange of genetic material between two homologous chromosomes’ nonsister chromatids. Crossover occurs during the pachytene substage ofprophase Iof meiosis I.

内容

1.Overview and Key Difference
2.什么是基因转换
3.What is Crossover
4.Similarities Between Gene Conversion and Crossover
5.Side by Side Comparison – Gene Conversion vs Crossover in Tabular Form
6.概括

什么是基因转换？

Gene conversion is a mechanism that involves a unidirectional transfer of genetic sequence information from a donor sequence to a highly homologous acceptor sequence. It is one of the two mechanisms of homologous recombination. In gene conversion, the donor sequence remains physically unchanged.

基因转化可以从完整的同源序列到包含双链断裂（DSB）的区域。因此，它是维修DSB的主要机制之一。此外，它可以发生在姐妹染色单体，同源染色体之间，甚至在同一染色单体或不同染色体上的同源序列之间发生。基因转化是各种人遗传疾病的主要原因。

What is Crossover?

Crossover is the exchange of genetic material between the nonsister chromatids of homologous chromosomes. It predominantly occurs during meiosis. Meiosis takes place when organisms produce sexual cells or gametes. During meiosis, homologous chromosomes recognize each other and form tightly bound pairs. Chromosomal crossover takes place in those events. Once they form tetrads, the genetic material exchange happens between nonsister chromatids. Genetic recombination is responsible for the genetic variation among the offspring.

Unequal crossover can also happen between two homologous chromosomes. It occurs when they break at slightly different loci. As a result, one chromosome receives double the amount of genetic material while the other chromosomes do not receive any. Hence, gene duplication happens in one chromosome, while gene deletion occurs in the other chromosomes.

What are the Similarities Between Gene Conversion and Crossover?

• 基因转化和交叉主要发生在减数分裂中。
• Moreover, they are possible during mitosis as well.
• They occur in chromosomes of eukaryotic organisms.
• Both are important driving forces in genome evolution.
• They are responsible for genetic variation.

基因转化和交叉之间有什么区别？

Gene conversion refers to the unidirectional transfer of genetic material from one allele to the other allele (from donor sequence to an acceptor sequence). Meanwhile, crossover refers to the exchange of genetic material between homologous chromosomes’ nonsister chromatids. So, this is the key difference between gene conversion and crossover. Moreover, gene conversion occurs during the mismatch repair of double-strand breaks during recombination. Whereas, crossover takes place during the gamete formation in sexual reproduction. Thus, this is another difference between gene conversion and crossover.

Below is a summary of the difference between gene conversion and crossover in tabular form.

概括– Gene Conversion vs Crossover

基因转化发生在双链断裂的修复期间。但是，在同源染色体的非染色单体之间进行有性繁殖期间发生了交叉。交叉负责人群中遗传变异的增强。两种同源染色体都接受了对方的遗传物质。在基因转化率中，供体序列在物理上保持不变，而受体序列从供体接收遗传信息。因此，这总结了基因转化和交叉之间的差异。

Reference:

1. Chen, Jian-Min, et al. “Gene Conversion in Human Genetic Disease.” Genes, MDPI, 22 Dec. 2010,Available here.
2. “Chromosomal Crossover.” Wikipedia, Wikimedia Foundation, 19 Feb. 2021,Available here.

Image Courtesy:

1. “Gene Conversion Types 2” By Schandanam at English Wikipedia(CC BY-SA 3.0)viaCommons Wikimedia
2. Abbyprovenzano的“染色体跨界” - 自己的作品(CC BY-SA 3.0)viaCommons Wikimedia