<Table> <Tr> <Td> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Holliday Junction </Td> </Tr> </Table> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Molecular structure of a Holliday junction . </Td> </Tr> </Table> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Molecular structure of a Holliday junction . From PDB: 3CRX ​ . </Td> </Tr> </Table> </Td> </Tr> </Table> <Tr> <Td> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Holliday Junction </Td> </Tr> </Table> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Molecular structure of a Holliday junction . </Td> </Tr> </Table> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Molecular structure of a Holliday junction . From PDB: 3CRX ​ . </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> </Td> </Tr> <Tr> <Td> Holliday Junction </Td> </Tr> </Table> <Tr> <Td> Holliday Junction </Td> </Tr>

When does the exchange of genetic material between chromatids on homologous chromosomes occur