What is the Difference Between Prophase and Metaphase

The main difference between prophase and metaphase is that chromosomes condense during prophase whereas homologous chromosome pairs align in the equatorial plate of the cell during metaphase. Furthermore, prophase is the first stage of nuclear division, following interphase while metaphase is the second stage of nuclear division, following prophase.

Prophase and metaphase are the two of the initial stages of the nuclear division responsible for preparing chromosomes for the division.

Key Areas Covered

1. What is Prophase
     – Definition, Process, Importance
2. What is Metaphase
     – Definition, Process, Importance
3. What are the Similarities Between Prophase and Metaphase
     – Outline of Common Features
4. What is the Difference Between Prophase and Metaphase
     – Comparison of Key Differences

Key Terms

Cell Division, Chromosomes, Interphase, Metaphase, Metaphase 1 and 2, Nuclear Division, Prophase, Prophase 1 and 2, Spindle Apparatus

What is Prophase

Prophase is the initial stage of nuclear division. It occurs in both mitosis and meiosis. The two prophase stages of meiosis I and meiosis II are known as prophase I and prophase II. Here, the prophase of mitosis and prophase I of meiosis I follow the interphase, which is a stage of cell cycle. Generally, the three stages of interphase are the G₁, S, and G₂ phases. Usually, a cell in the G₁ phase undergoes protein synthesis and normal growth. When it enters the S phase, DNA replicates in the chromosomes, forming sister chromatids. Then, the cell enters the G₂ phase, which directly precedes nuclear division. However, prophase II of meiosis II just follows cytokinesis that occurs after meiosis I.

Figure 1: Two Mouse Cell Nuclei in Prophase
(Condensed Chromosomes – Red, Nuclear Envelope – blue, Microtubules- Green)

Furthermore, the three major events of prophase are the condensation of chromosomes, disappearance of the nucleolus and nuclear membrane, and the formation of the spindle apparatus. Here, the condensed chromosomes can be observed under the microscope during prophase. Additionally, the disappearance of nucleus frees the chromosomes. Also, the migration of centrioles to the opposite poles of the cell remarks the formation of the spindle apparatus.

What is Metaphase

Metaphase is the second stage of nuclear division, following prophase in both mitosis and meiosis. It is important to note that meiosis undergoes two metaphase events known as metaphase I and metaphase II. Here, the major event of metaphase of mitosis and metaphase I of meiosis I is the alignment of homologous chromosomes along the equatorial plate of the cell defined by the spindle apparatus. However, during the metaphase II of meiosis II, individual chromosomes align along the equatorial plate as homologous pairs have been separated during meiosis I.

Figure 2: Metaphase Chromosomes in Green

Furthermore, a substage called prometaphase occurs before the metaphase. And, this phase is responsible for the wrapping of proteins around the centromere, forming kinetochores to which the microtubules of the spindle apparatus attach. Contractions or relaxations of microtubules are responsible for the positioning of chromosomes at the equatorial plate during metaphase. However, improper arrangements of chromosomes during metaphase results in unequal separation of chromosomes between the two daughter cells, resulting in genetic disorders.

Similarities Between Prophase and Metaphase

• Prophase and metaphase are the two initial stages of the nuclear division.
• They are responsible for preparing chromosomes for the division.
• Also, both occur during mitosis and meiosis. Here, meiosis undergoes two prophase and metaphase events separately.
• Furthermore, chromosomes occur in the condensed form during both stages.
• Besides, spindle apparatus play a key role in moving chromosomes in both stages.

Difference Between Prophase and Metaphase

Definition

Prophase refers to the initial stage of mitosis and of the mitotic division of meiosis characterized by the condensation of chromosomes consisting of two chromatids, disappearance of the nucleolus and nuclear membrane, and formation of the mitotic spindle. Metaphase, on the other hand, refers to the second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers. Thus, this is the fundamental difference between prophase and metaphase.

Consequence

Another difference between prophase and metaphase is that prophase follows interphase and it is the first stage of the nuclear division while metaphase is the second stage of nuclear division, following prophase.

Events

Moreover, an important difference between prophase and metaphase is the events that take place during each process. Condensation of chromosomes, disappearance of the nucleolus and nuclear membrane, and formation of mitotic spindle are the major events of prophase while the alignment of the condensed chromosomes in the equatorial plate is the major event of metaphase.

Importance

Above all, the main difference between prophase and metaphase is that the condensed chromosomes are observable under the microscope during prophase while the proper line up of chromosomes in the equatorial plate during metaphase ensures the equal separation of them to the opposite poles of the cell.

Conclusion

Prophase is the initial stage of nuclear division. It occurs in cells that have undergone interphase. The three major events of prophase are the condensation of chromosomes, disappearance of the nucleolus and nuclear membrane, and the formation of the spindle apparatus. On the other hand, the second stage of nuclear division, following prophase is metaphase. This phase is characterized by the alignment of homologous chromosomes along the equatorial plate of the cell. Both prophase and metaphase are two important stages of nuclear division and they prepare chromosomes of the cell for the subsequent separation to opposite poles. Therefore, the main difference between prophase and metaphase is the type of events that occur.

References:

1. “Prophase.” Nature News, Nature Publishing Group, Available Here.
2. “Metaphase.” Nature News, Nature Publishing Group, Available Here.

Image Courtesy:

1. “3D-SIM-3 Prophase 3 color” By Lothar Schermelleh – Lothar Schermelleh (CC BY-SA 3.0) via Commons Wikimedia   
2. “Metaphase chromosomes” By Simon Caulton – Own work (CC BY-SA 3.0) via Commons Wikimedia