Problem 3 - Campbell Biology

Question

Melosis II is similar to mitosis in that (A) sister chromatids separate during anaphase. (B) DNA replicates before the division. (C) the daughter cells are diploid. (D) homologous chromosomes synapse.

Step-by-Step Solution

Answer

(A) sister chromatids separate during anaphase.

Step 1: Understanding Meiosis II and Mitosis

Meiosis II and mitosis are both types of cell division. Meiosis II follows Meiosis I and results in four haploid cells, while mitosis results in two diploid cells.

Step 2: Examine the Options

Review each of the options to determine which one applies to both Meiosis II and mitosis.

Step 3: Option A: Sister Chromatids Separation

In both Meiosis II and mitosis, sister chromatids separate during anaphase. This separation ensures that each daughter cell receives an identical set of chromosomes.

Step 4: Option B: DNA Replication

DNA replication does not occur in Meiosis II; it occurs before Meiosis I. However, DNA replication occurs before mitosis.

Step 5: Option C: Daughter Cells' Chromosome Count

Meiosis II produces four haploid cells, while mitosis produces two diploid cells. Hence, daughter cells are not diploid in Meiosis II.

Step 6: Option D: Homologous Chromosomes Synapse

Homologous chromosomes synapse, or pair up, during Meiosis I, not during Meiosis II or mitosis.

Step 7: Conclusion

After reviewing the options, only option (A) is correct. Both Meiosis II and mitosis involve the separation of sister chromatids during anaphase.

Key Concepts

Sister Chromatid Separation

In both Meiosis II and Mitosis, a crucial process occurs during anaphase: the separation of sister chromatids. Sister chromatids are identical copies of a chromosome linked together by a centromere. During anaphase of Mitosis and Meiosis II, the centromeres divide and the sister chromatids are pulled apart.
This ensures that each daughter cell ends up with an equal and identical set of chromatids.

• In Mitosis, this step ensures that each of the two daughter cells is diploid (2n), possessing the same number of chromosomes as the original cell.
• In Meiosis II, it helps to produce four haploid cells (n), each carrying half the number of chromosomes compared to the diploid parent cell.

Understanding this separation is key to grasping how genetic information is equally distributed in cells derived from both Mitosis and Meiosis II.

Cell Division

Cell Division is the process where one cell divides into two or more daughter cells. This encompasses two main types: Mitosis and Meiosis.
Mitosis involves one round of division resulting in two identical diploid cells. It's crucial for growth, development, and tissue repair in multicellular organisms. Meiosis, on the other hand, involves two rounds of division (Meiosis I and Meiosis II) and results in four non-identical haploid cells.

• Meiosis I reduces the chromosome number by half, separating homologous chromosomes.
• Meiosis II, akin to Mitosis, separates sister chromatids to ensure each gamete gets a single copy of each chromosome.

Both Mitosis and Meiosis ensure that new cells receive the correct number and type of chromosomes, maintaining genetic stability and diversity.

Haploid vs Diploid Cells

Understanding the difference between haploid and diploid cells is fundamental in cell biology.
Diploid cells (2n) contain two complete sets of chromosomes, one from each parent. Most of the body's somatic cells are diploid. Haploid cells (n), however, have only one set of chromosomes. These are essential for sexual reproduction and are found in gametes (sperm and egg cells).

• During Mitosis, diploid cells divide to create two identical diploid daughter cells, preserving chromosome number.
• During Meiosis, diploid cells undergo two division cycles to produce four haploid cells. In Meiosis I, homologous chromosomes are separated, reducing the chromosome number by half. Meiosis II, which resembles Mitosis, ensures that each haploid cell ends up with a single set of chromosomes.

Recognizing whether cells are haploid or diploid after division helps us understand modes of inheritance and genetic variability in offspring.