Problem 5 - Campbell Biology

Question

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in \begin{equation} \begin{array}{l}{\text { (A) cells with more than one nucleus. }} \\ {\text { (B) cells that are unusually small. }} \\ {\text { (C) cells lacking nuclei. }} \\ {\text { (D) cell cycles lacking an S phase. }}\end{array} \end{equation}

Step-by-Step Solution

Answer

The cells will have more than one nucleus. The correct answer is (A).

Step 1: Understanding Mitosis and Cytokinesis

Mitosis is the process of nuclear division, where one nucleus divides into two nuclei, each with an identical set of chromosomes. Cytokinesis is the process of cytoplasmic division, where the cell splits into two separate daughter cells.

Step 2: Analyzing the Impact of Mitosis Without Cytokinesis

If mitosis occurs without cytokinesis, the cell will undergo nuclear division but not cytoplasmic division. This means that multiple nuclei will form within a single cell, as the cytoplasm is not divided to create separate cells.

Step 3: Identifying the Correct Option

Based on the understanding that mitosis without cytokinesis results in a single cell with multiple nuclei, the correct option is (A) cells with more than one nucleus.

Key Concepts

Nuclear Division

Nuclear division is a key part of the cell cycle. It involves the splitting of the nucleus into two distinct nuclei.
During nuclear division, the cell's DNA is duplicated and distributed equally between the two new nuclei. This stage ensures that each new nucleus gets an identical set of chromosomes.
Nuclear division occurs through a process called mitosis. Mitosis has several phases: prophase, metaphase, anaphase, and telophase.
Each phase plays an important role in making sure the DNA is accurately replicated and divided.
It's important to remember that nuclear division is just one part of the cell cycle. It has to be followed by cytokinesis to complete cell division.

Cytoplasmic Division

Cytoplasmic division, also known as cytokinesis, is the process where the cell's cytoplasm divides to form two separate daughter cells.
This step follows nuclear division and ensures that each daughter cell gets its own cytoplasm and organelles.
Cytokinesis differs in plant and animal cells. In animal cells, the cell membrane pinches inwards to separate the cytoplasm. In plant cells, a cell plate forms along the centerline of the cell, eventually dividing it into two.
If mitosis happens without cytokinesis, the result is a single cell with multiple nuclei. This can lead to issues with cell function and size.

Multinucleated Cells

Multinucleated cells are cells that have more than one nucleus. This can occur due to mitosis without cytokinesis.
When cytokinesis doesn't happen, the cell ends up with multiple nuclei inside a shared cytoplasm.
Multinucleated cells are found commonly in certain tissues like muscle tissues. They are also seen in some disease conditions. However, they result from a unique cellular process.
These cells can continue to grow and function, but they are not typical of most of the body's cells.