AP BIOLOGY

CELL DIVISION

MEIOSIS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Synapsis occurs during
A
Prophase of mitosis
B
Prophase I of meiosis
C
Prophase II of meiosis
D
Both a and b are correct
Explanation: 

Detailed explanation-1: -In meiosis I, synapsis formation occurs in the zygotene stage of prophase-I. It is the second stage of prophase-I. During this stage, the chromosomes start pairing together and this process of association called synapsis. Such paired chromosomes are called homologous chromosomes.

Detailed explanation-2: -Synapsis is the pairing of homologous chromosomes during prophase I of meiosis. The synaptonemal complex is the protein scaffolding structure present between homologous chromosomes that facilitates genetic recombination. Following diakinesis, the rest of meiosis I proceeds quite similarly to mitosis.

Detailed explanation-3: -Meiosis I, the first meiotic division, begins with prophase I. During prophase I, the complex of DNA and protein known as chromatin condenses to form chromosomes. The pairs of replicated chromosomes are known as sister chromatids, and they remain joined at a central point called the centromere.

Detailed explanation-4: -Synapsis of homologous chromosomes takes place during prophase I of meiosis.

Detailed explanation-5: -During prophase I, homologous chromosomes pair and form synapses, a step unique to meiosis. The paired chromosomes are called bivalents, and the formation of chiasmata caused by genetic recombination becomes apparent. Chromosomal condensation allows these to be viewed in the microscope.

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