Question

During prophase 1 the chromosomes and become

Answer 1

During prophase I, the chromatin condenses into visible chromosomes and forms tetrads of homologous chromosomes held together at chiasmata.

Step-by-step explanation:

During prophase I, the loosely packed chromatin coils and condenses into visible chromosomes. Each chromosome becomes visible with its identical partner attached, forming the familiar X-shape of sister chromatids. The nucleolus disappears early during this phase, and the nuclear envelope also disintegrates. At the end of prophase I, the pairs of homologous chromosomes are held together only at the chiasmata and are called tetrads because the four sister chromatids of each pair of homologous chromosomes are now visible.

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Answer 2

During prophase I, the chromosomes condense and become visible inside the nucleus. Because each chromosome was duplicated during the S phase that occurred just before prophase I, each now consists of two sister chromatids joined at the centromere. This arrangement means that each chromosome has the shape of an X.