Question

In synaptonemal complex strand exchange between chromosomes occurs at this average distance?

1) 120-800 nm
2) 120-400 nm
3) 400-800 nm
4) 2-120 nm

Answer 1

The precise average distance for strand exchange in the synaptonemal complex was not provided in the materials. This structure facilitates chromosomal segment exchanges at multiple points along the chromosomes, aided by recombination nodules marking the eventual chiasmata.

Step-by-step explanation:

The synaptonemal complex is a protein structure that forms during the first prophase of meiosis. It plays a critical role in crossing over, where chromosomal segments are exchanged between homologous non-sister chromatids. The precise distance at which strand exchange occurs is not specified in the provided material, but the structure of the synaptonemal complex facilitates this exchange at regular intervals along the chromosomes.

Crossing over is observable as chiasmata under a microscope. The synaptonemal complex supports the exchange by aligning the genes on homologous chromosomes precisely with each other and forming a tight pairing known as synapsis. After the crossover events, the synaptonemal complex breaks down, and what remains are chiasmata holding the homologous chromosomes together until they are separated into tetrads by the end of prophase I.

Therefore, while an average distance was not directly provided, this exchange happens at numerous points along the length of the synaptonemal complex as facilitated by structures called recombination nodules which mark the points of later chiasmata.