Problem 3 - Campbell Biology

Question

Meiosis II is similar to mitosis in that \begin{equation}\begin{array}{l}{\text { (A) sister chromatids separate during anaphase. }} \\ {\text { (B) DNA replicates before the division. }} \\\ {\text { (C) the daughter cells are diploid. }} \\ {\text { (D) homologous chromosomes synapse. }}\end{array}\end{equation}

Step-by-Step Solution

Answer

A) Sister chromatids separate during anaphase.

Step 1: Understanding Meiosis II and Mitosis

Meiosis II is the second division in meiosis, following Meiosis I. Like mitosis, it involves the separation of chromosomes. The critical point is to notice what both processes have in common.

Step 2: Examine the Options

Look at each option provided and determine if it correctly describes an event that is common to both meiosis II and mitosis.

Step 3: Analyze Option A

Option A states that sister chromatids separate during anaphase. Both meiosis II and mitosis involve the separation of sister chromatids at the anaphase stage. This is correct.

Step 4: Analyze Option B

Option B states that DNA replicates before the division. This happens before both processes, but it is not a part of the division itself during meiosis II or mitosis. Therefore, this option is incorrect.

Step 5: Analyze Option C

Option C states that daughter cells are diploid. In mitosis, the daughter cells are diploid; however, in meiosis II, the daughter cells are haploid. Thus, this option is incorrect.

Step 6: Analyze Option D

Option D states that homologous chromosomes synapse. This occurs during meiosis I, not meiosis II or mitosis. Thus, this option is incorrect.

Step 7: Conclusion

Based on the analysis, the option that correctly describes an event common to both meiosis II and mitosis is Option A.

Key Concepts

Meiosis II

Meiosis II is the second division phase in meiosis, which follows Meiosis I. In this stage:

• The main goal is to separate the sister chromatids.
  
• This process resembles mitosis in many ways.
  

Unlike meiosis I, where homologous chromosomes are separated, the chromatids here are what get pulled apart.
There is no DNA replication between the two meiosis stages, which ensures the cells produced are haploid.
The end result of meiosis II is four non-identical haploid cells, which is necessary for sexual reproduction to maintain chromosome numbers across generations.

Mitosis

Mitosis is the process by which a eukaryotic cell divides its nucleus, resulting in two identical daughter cells. Here are some key points:

• The main purpose is for growth and repair.
  
• Unlike meiosis, mitosis involves only one division cycle.
  

During interphase, which occurs before mitosis, DNA is replicated. This prepares each chromosome to consist of two sister chromatids.
As mitosis progresses, these chromatids are evenly divided between the two new nuclei.
Sea sponge cells, for example, often use mitosis for their asexual reproduction.

Anaphase

Anaphase is a critical phase in both meiosis II and mitosis:

• It's the stage where sister chromatids are pulled apart.
  
• This ensures that each new cell will receive an identical set of chromosomes.
  

During anaphase, the chromatids move to opposite poles of the cell. This movement is powered by spindle fibers attached to the centromeres of the chromatids.
By the end of anaphase, the sister chromatids are fully separated.
The resulting separation is crucial for the genetic consistency in mitosis or the genetic diversity in meiosis II. Differences in how this phase is regulated can explain the variation between the two processes.