Question

Synaptonemal complex is site of
A. Spindle attachment
B. Replication
C. Chromatid separation
D. Chromosome alignment and recombination

Answer 1

The second stage of meiosis prophase-$1$ is zygotene. It is preceded by the leptotene stage, during which chromosomes uncoil and condense. Homologous chromosomes come together and pair in the zygotene stage. Synapsis is the process of homologous chromosomes being paired together. A protein complex known as the synaptonemal complex connects the paired chromosomes. In the Pachytene stage, the synaptonemal complex stabilises the pairing and allows crossing over or recombination.

Complete answer:
Option A: Microtubules, which are long protein fibres that extend in all directions from the centrioles, create a spindle. Some microtubules join to protein complexes termed kinetochores to connect the poles to the chromosomes.
So, option A is incorrect.
Option B: During the cell cycle, DNA replication is the process of copying DNA. copied. A eukaryotic cell's nucleus is where DNA replication takes place. nucleus. During the (M stage / S stage) of the cell cycle, DNA is duplicated.
So, option B is incorrect.
Option C: The mitotic spindle is a structure that separates the chromosomes. The mitotic spindle is made up of microtubules, which are long proteins connected to a chromosome on one end and the cell pole on the other. At their centromeres, the sister chromatids are split at the same time.
So, option C is incorrect.
Option D: A proteinaceous zipper-like structure formed between homologous chromosomes is known as the synaptonemal complex. Its construction aids in chromosome condensation, pairing, and recombination.
So, option D is correct.

Therefore, Option D is the correct answer.

Note:
The synaptonemal complex (SC) is a protein structure that arises during meiosis between homologous chromosomes and is hypothesised to mediate synapsis and recombination in eukaryotes. It is assumed to serve primarily as a scaffold that allows interacting chromatids to finish their crossing actions. The synaptonemal complex is made up of three parts: two parallel lateral areas and a centrepiece. At gametogenesis, this can be seen in both males and females during the pachytene stage of the first meiotic prophase.