During prophase – I of meiosis homologous chromosomes pair with each other to form bivalent. A bivalent is an association of:
a. Two chromatids and two centromeres
b. Four chromatids and two centromeres
c. Four chromatids and four centromeres
d. Two chromatids and one centromere
Please tell me the correct option.
Answers
In the prophase stage of meiosis I, when homologous chromosomes pair, structures called as bivalents are produced which comprise of two homologous chromosomes each. ... Thus, each bivalent is actually a tetrad of chromatids - two sister and two non-sister chromatids.
Answer:
Pairing of homologous chromosomes is a defining characteristic of meiosis and distinguishes meiosis from mitosis. Homologous chromosomes pair during prophase stage of meiosis I. In the prophase stage of meiosis I, when homologous chromosomes pair, structures called as bivalents are produced which comprise of two homologous chromosomes each. Each chromosome of each bivalent structure, in turn comprises of two sister chromatids joined at the centromere. Thus, each bivalent is actually a tetrad of chromatids - two sister and two non-sister chromatids. Two chromatids joined together at the centromere are called sister chromatids and two chromatids which are not joined at the centromere, nevertheless are a part of same bivalent are called non-sister chromatids. Each bivalent shall possess two centromere - one each from the two homologous chromosomes.