The molecular process which results in the formation of recombinant chromosomes is initiated by:
A)a single-stranded break in one of the chromatids.
B)a double-stranded break in one of the chromatids.
C)the formation of heteroduplex DNA.
D)the invasion of single-stranded DNA.
E)a Holliday junction.

Question

Quizplus · Accepted Answer

The molecular process leading to the formation of recombinant chromosomes starts with a double-stranded break (DSB) in one of the chromatids. This break can occur spontaneously or can be induced by factors such as radiation or chemicals.

Answer: D
 Invasion of single-stranded DNA (ssDNA) is another critical step in the process of chromosome recombination. After a double-stranded break is generated, a single-stranded DNA molecule created by the nucleolytic degradation of the broken strand invades the non-broken strand of a homologous chromosome, forming a joint molecule called a D-loop.

Answer: E
 A Holliday junction is a structural intermediate in the process of meiotic recombination, leading to genetic exchange between homologous chromosomes or chromatids. It is formed when two homologous DNA molecules or sister chromatids form a cross-like structure that contains two heteroduplex regions, which can undergo resolution to form recombinant molecules.

The Molecular Process Which Results in the Formation of Recombinant