Question

Match the statement to interphase or the phase of mitosis in the key. a. metaphase b. interphase c. telophase d. prophase e. anaphase. Duplicated chromosomes become visible.

Short answer

The statement "Duplicated chromosomes become visible" applies to the prophase of mitosis. Therefore, the correct match is \(d. prophase\).

Step-by-step solution

Understand each phase of the cell cycle

Before matching the statement to the correct phase, it is important to have a basic understanding of each phase involved in the cell cycle. The cell cycle consists of two main parts: interphase and mitosis. Interphase is when the cell is not dividing, and it is comprised of three substages: G1, S, and G2. During interphase, the cell grows and duplicates its chromosomes in preparation for division. Mitosis consists of four main phases: prophase, metaphase, anaphase, and telophase, followed by cytokinesis. Each of these phases plays a vital role in the process of cell division.

Analyze the statement

The statement given is "Duplicated chromosomes become visible." This statement refers to a specific event during the cell cycle when the chromosomes, which have been duplicated during interphase, become visible under the microscope.

Match the statement to the correct phase

Now that we have an understanding of the cell cycle's phases, we can conclude that chromosomes becoming visible occurs during prophase, the first phase of mitosis. During prophase, the chromosomes condense, and the duplicate chromatids become visible under the microscope. Answer: \[d. prophase\]

Key concepts

Interphase

Interphase is a crucial part of the cell cycle, accounting for about 90% of the total cycle duration. During this phase, the cell is not actively dividing. Instead, it is focused on growth and preparing itself for division.

• G1 phase - This is the first stage of interphase where the cell grows larger and makes more ribosomes and proteins.
• S phase - In this stage, the cell synthesizes a complete copy of the DNA in its nucleus, leading to chromosome duplication. This is essential for ensuring that each daughter cell has the correct number of chromosomes after mitosis.
• G2 phase - The cell continues to grow and produces proteins and organelles. It also begins to reorganize its contents in preparation for mitosis.

Once interphase is completed, the cell has duplicated its DNA and is now prepared to enter mitosis.

Mitosis

Mitosis is the part of the cell cycle where the cell divides its duplicated DNA between two new cells. This process ensures genetic consistency across all cells that derive from the original cell.
Mitosis happens in a series of phases, each with its distinct events:

• Prophase - Chromosomes condense and become visible. The mitotic spindle begins to form, and the nuclear envelope starts to break down.
• Metaphase - Chromosomes are aligned at the cell's equatorial plane, called the metaphase plate, ensuring each new cell will receive one copy of each chromosome.
• Anaphase - The sister chromatids are pulled apart toward opposite poles of the cell.
• Telophase - New nuclear envelopes begin to form around each set of chromosomes, which de-condense back into a less visible state.

Followed by cytokinesis, the cell fully divides its cytoplasm and organelles between the two new daughter cells.

Prophase

Prophase is the first stage of mitosis and is marked by several key events. A key characteristic of prophase is the condensation of chromatin, making chromosomes first become visible under a microscope.
During prophase:

• The chromatin fibers become more tightly coiled, condensing into discrete chromosomes that are visible with a light microscope.
• Each chromosome, already duplicated during interphase, appears as two identical sister chromatids joined at the centromere.
• The mitotic spindle forms as microtubules grow out from centrosomes that are moving to opposite poles of the cell.
• The nuclear envelope begins to disassemble, allowing microtubules to attach to chromosomes at the centromeres.

Prophase sets the stage for the following phases of mitosis, ensuring that the chromosomes are correctly aligned and prepared for segregation.

Chromosome Duplication

Chromosome duplication, a critical part of cell division, occurs during the S phase of interphase. It is vital for making sure each daughter cell receives the correct number of chromosomes.
Here's how chromosome duplication works:

• Each chromosome in the nucleus of a cell is composed of DNA, which contains the genetic instructions for the organism.
• During the S phase, DNA replication occurs, where the DNA double helix unwinds, and each strand serves as a template for generating a new complementary strand.
• As a result, chromosomes are duplicated resulting in two identical DNA molecules known as sister chromatids, linked together by a centromere.

This duplication ensures that during mitosis, each daughter cell inherits an exact copy of DNA from the parent cell, maintaining genetic continuity.