MCQ of the Day

A  30 years old female is in the proccess of invitro fertilization.  She has normal menstrual history.  The gynecologist is worried whether she has normal ova formed or not.  The DNA of the ova will have a special pattern in its nucleus.  Which phase arrangement of the DNA material is normal for in vitro fertilization?

 

 

1. Meiosis 1 Metaphase
2. Meiosis 2 Metaphase
3. Meiosis 1 Prophase
4. Meiosis 2 Prophase
5. Mitosis prophase
    
    
    

 

 

 

 

 

 

 

 

 

Answer:d

Explanation: 

The ova at the time of ovulation are in Meiosis 2 Prophase.  Spindle fibers form the centrioles and the chromosomes attach themselves.  Chromosomes are not copied again before Prophase 2.  The membrane around the nucleus breaks apart and nucleolus is not seen.

(Choice a) During metaphase chromosomes line at the equator of the cell.  Homologous pairs move together along the metaphase plate.

(Choice b) In metaphase 2, the centromeres contain two kinetochores that attach to spindle fibers from the centrosomes at opposite poles.

(Choice c) Meiosis Prophase I is the longest phase of meiosis. During prophase I, homologous chromosomes pair and exchange DNA in a process called homologous recombination and chromosomal crossover.

(Choice e) Mitosis is mostly seen in somatic cells.  Gametes show Meiosis.

 

Educational Objective: 

The oocytes are in the Prophase of 2^nd meiotic division.  Meiosis I and II are each divided into prophase, metaphase, anaphase, and telophase stages, similar in purpose to their analogous subphases in the mitotic cell cycle. Therefore, meiosis includes the stages of meiosis I (prophase I, metaphase I, anaphase I, telophase I) and meiosis II (prophase II, metaphase II, anaphase II, telophase II).