Question

A) Formulate a one sentence hypothesis which states which stages of mitosis (prophase, prometaphase, metaphase, anaphase, or telophase) will be most common to the least common. Note: A hypothesis should be written as a statement (claiming something to be true). Additionally, a hypothesis must be testable experimentally.

B) Describe your rationale for your hypothesis. Do you think all stages will have equal counts? Why or why not? If not, which stage of mitosis do you think will be most, least, etc. common in your data and why? What do you know about what happens at each stage of cell division, and how long (relatively) might that require?

Answer 1

A.] The stages of mitosis from most common to the least common (on the basis of time duration and distinction) is Prophase>Telophase>Metaphase>Anaphase>Prometaphase.

B.]  Prophase the most common and longest phase in Mitosis; this is because it takes long time to separate the chromatin, connect spindles, and preparation for the rest.

Anaphase is considered to be the shortest stage of the cell cycle because this stage involves only the separation of sister chromatids and their migration towards opposite poles.

But, Prometaphase is a more a indistinct phase. It is not always presented as a distinct part in the mitosis.

All the stages do not have equal counts though all of them are necessary in completing a mitotic phase of cell cycle. The functioning of a cell in different stages are different, they take unequal time duration to perform its phase.

As it is mentioned earlier, there is a relevancy in their functioning period, with prophase the longest and most significant phase, and anaphase as shortest; prometaphase as least significant phase. The order of the stages in mitosis is - [Prophase- Prometaphase- Metaphase- Anaphase- Telophase].

In Prophase, cell spend most of its time doubling up its DNA, chromosomes appear condensed and nuclear envelope not apparent; formation of asters, spindle take place.

In Prometaphase, the nuclear membrane breaks apart into numerous membrane vesicles and the chromosomes inside form protein structures called kinetochores.

In Metaphase, thick-coiled chromosomes, each with two chromatids are lined up on a metaphase plate.

In Anaphase, the daughter chromatids of each chromosome seperates/splits and moves towards two poles taking part in equatorial division (divides nuclear matter into two equal and similar halves).

In Telophase, the chromatids are at poles and become more diffuse; new nuclear membrane forms at each poles which surrounds the chromosomes; nucleolus reforms.

Relative time division of each mitotic phases lie within the following limits: Prophase- 30 to 60 minutes; Prometaphase- falls within metaphase; Metaphase-2 to 10 minutes; Anaphase- 2 to 3 minutes; Telophase- 3 to 12 minutes.