Chapter 11

Question 0

Homologous recombination occurs between homologous chromosomes during ___
• The process scrambles the genes of maternal and paternal chromosomes resulting in nonparental combinations in the offspring
• Meiotic recombination forms physical links between homologous chromosomes that allow them to _____ so they separate properly during meiotic metaphase
• It also plays an important role in allowing cells to deal with DNA damage by _____
• Elucidation of the molecular mechanism of recombination had led to the development of methods to manipulate genes. (gene knockout)

Answer 0

Homologous recombination occurs between homologous chromosomes during meiosis
• The process scrambles the genes of maternal and paternal chromosomes resulting in nonparental combinations in the offspring
• Meiotic recombination forms physical links between homologous chromosomes that allow them to align properly during meiotic prophase so they separate properly during meiotic metaphase
• It also plays an important role in allowing cells to deal with DNA damage by recombination repair
• Elucidation of the molecular mechanism of recombination had led to the development of methods to manipulate genes. (gene knockout)

Question 1

Holliday Junctions
• Branch migration in this intermediate yields a Holliday junction with 2 strands exchanging between homologous chromosomes
• Branch in the Holliday junction can migrate in either direction by _____in a process called branch migration
• This migration process does not occur at a useful rate spontaneously
– DNA unwinding required
– Unwinding requires ___ and energy from ATP

Answer 1

Holliday Junctions
• Branch migration in this intermediate yields a Holliday junction with 2 strands exchanging between homologous chromosomes
• Branch in the Holliday junction can migrate in either direction by breaking old base pairs and forming new ones in a process called branch migration
• This migration process does not occur at a useful rate spontaneously
– DNA unwinding required
– Unwinding requires helicase activity and energy from ATP

Question 2

Resolving Holliday junction is a Key Step to finishing genetic exchange
Holliday junctions can be resolved by nicking two of its strands
Yielding: 2 noncrossover recombinant DNAs with patches of heteroduplex - produced if the inner strands are nicked (patch product, two of the four strands are completely from the parental DNA molecules)
2 crossover recombinant DNAs that have traded flanking DNA regions - produced if the outer strands are nicked (splicing product)

Answer 2

Resolving Holliday junction is a Key Step to finishing genetic exchange
Holliday junctions can be resolved by nicking two of its strands
Yielding:
2 noncrossover recombinant DNAs with patches of heteroduplex - produced if the inner strands are nicked (patch product, two of the four strands are completely from the parental DNA molecules)
2 crossover recombinant DNAs that have traded flanking DNA regions - produced if the outer strands are nicked (splicing product)