Question

Chiasma is a cross-shaped configuration formed between, which of the following chromosome?

• A. Sister chromatids of homologous chromosomes
• B. Sister chromatids of non-homologous chromosomes
• C. Non-sister chromatids of homologous chromosomes
• D. Non-sister chromatids of non-homologous chromosomes

Answer 1

Answer: (C)

Non-sister chromatids of homologous chromosomes

Meiosis comprises of two divisions meiosis I and meiosis II.

• Homologous chromosomes pair during meiosis I.
• Crossing over occurs during meiosis I. This is called synapsis.
• The synapsis occurs between homologous chromosomes and facilitates crossing over.
• The crossing over occurs between non-sister chromatids of a homologous pair of chromosomes.
• The exact point of crossing over is revealed by the formation of cross-shaped structures or chiasma formation during prophase I.

So, the correct answer is option C.