Question

If a parent cell has 18 chromosomes before mitosis, how many chromosomes will the daughter cells have? a. 18 b. 36 c. 9 d. 27

Short answer

Each daughter cell will have 18 chromosomes after the process of mitosis, as the chromosomes are duplicated and divided equally during mitosis, ensuring that the daughter cells have the same amount of genetic information as the parent cell. Therefore, the answer is a. 18.

Step-by-step solution

Understand Mitosis

Mitosis is a type of cell division, where a cell divides into two identical daughter cells. It is a crucial process in the growth, development, and repair of multicellular organisms. During mitosis, the cell's genetic material (chromosomes) is duplicated and then divided equally between the two daughter cells, ensuring that they have the same amount of genetic information as the parent cell.

Consider the Parent Cell's Chromosomes

The question states that the parent cell has 18 chromosomes before mitosis occurs. It is important to note that, during mitosis, the genetic material (chromosomes) is duplicated but not increased in number, as the purpose of the process is to divide the cell into two identical daughter cells with the same genetic information.

Determine Daughter Cell Chromosomes

Since the chromosomes are duplicated and divided equally during mitosis, each daughter cell will have the same number of chromosomes as the parent cell. In this case, the parent cell has 18 chromosomes, so each daughter cell will also have \(18\) chromosomes. So, the correct answer is: a. 18

Key concepts

Cell Division

Cell division is a fundamental biological process where a single cell divides to produce two new cells. It is essential for growth, repair, and reproduction in living organisms. Two main types of cell division are known as mitosis and meiosis. Mitosis leads to the production of two genetically identical daughter cells, each having the same number of chromosomes as the original cell.

During mitosis, the cell undergoes phases such as prophase, metaphase, anaphase, and telophase, each serving distinct functions in the preparation and division of genetic material. For instance, during metaphase, chromosomes align at the cell's equator before being separated into each new cell. This precise division is key to maintaining the species' chromosome count across generations and is why, in the exercise, the daughter cells end up with the same number of chromosomes as the parent cell.

Chromosomes

Chromosomes are the structures within cells that hold genetic information, made of DNA and proteins. In eukaryotic cells, which include human cells, the DNA is tightly coiled around proteins called histones, forming the chromosome. Each species has a characteristic number of chromosomes; for example, humans have 46. When a cell prepares to divide during mitosis, its chromosomes are duplicated so each new cell receives an identical set of genetic blueprints.

This duplication is crucial to ensure that, during mitosis, each daughter cell receives the proper amount and the exact same genetic material as the parent cell. Additionally, if there are any issues in the replication or separation of chromosomes, it can lead to genetic disorders or diseases. Therefore, the fidelity of chromosome duplication and segregation is vital to the organism's health and continuity.

Genetic Material

Genetic material refers to molecules that store the information necessary for building and maintaining an organism, and for passing traits to offspring. DNA is the primary genetic material in most organisms. Within the DNA, specific segments called genes carry the instructions for making proteins and conducting life processes.

In the context of mitosis, the genetic material is tightly regulated to ensure each daughter cell receives an exact copy. The entire process is geared towards preserving the genetic sequence and maintaining the integrity of the organism. The exercise illustrates this precision in genetic replication. If a cell has 18 chromosomes, its genetic material is duplicated and then equally divided, so each of the two resulting daughter cells will indeed have 18 chromosomes, upholding the continuity of genetic information.