Question

During which of phase of meiosis is then nuclear envelope intact?

Group of answer choices

a G1

b Interkinesis

c Leptotene

d Anaphase

Answer 1

Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. It is used by sexually reproducing organisms to produce gametes. Gametes are our sex cells – sperm in males, eggs in females. There are two stages or phases of meiosis: meiosis I and meiosis II, which are further subdivided.

a. G1 phase: Before a dividing cell enters meiosis, it undergoes a period of growth called Interphase. G1 or Gap 1 phase is a part of this interphase. It occurs prior to the synthesis of DNA. The cell increases in mass in preparation for cell division. In this phase, the nuclear envelope remains intact.

b. Interkinensis: In some species, cells enter another brief interphase before entering meiosis II, known as Interkinesis. Interkinesis lacks an S phase, so chromosomes are not duplicated. During this period, the nuclear membrane in each of the two cells, produced in meiosis I, re-form around the chromosomes. Thus, the nuclear envelope is intact.

c. Leptotene or Leptonema: It is a substep of prophase I where condensation of chromatin occurs. The nuclear envelope is intact and it breaks down later in the prophase I phase. In this step chromatin condensation takes place to form a chromosome structure.

d. Anaphase: This phase is similar in both mitosis and meiosis. The nuclear envelope is no longer intact. In this phase, the chromosomes move towards opposite poles. The microtubules such as the kinetochore fibers interact to pull the chromosomes to the cell poles.