The portal has been deactivated. Please contact your portal admin.

Question Video: Identifying the Relationship between the Chromosomal Number of Gametes and Somatic Cells Biology

Which of the following is correct about the somatic cells (body cells) of an organism and the gametes (sex cells) that the organism produces? [A] Gametes contain double the genetic material of a somatic cell. [B] Gametes contain half the genetic material of a somatic cell. [C] Gametes contain around 75% of the DNA that a somatic cell contains. [D] The genetic material of a somatic cell is DNA, whereas the genetic material of a gamete is RNA. [E] The genetic material of a somatic cell is RNA, whereas the genetic material of a gamete is DNA.

04:15

Video Transcript

Which of the following is correct about the somatic cells, body cells, of an organism and the gametes, sex cells, that the organism produces? (A) Gametes contain double the genetic material of a somatic cell. (B) Gametes contain half the genetic material of a somatic cell. (C) Gametes contain around 75 percent of the DNA that a somatic cell contains. (D) The genetic material of a somatic cell is DNA, whereas the genetic material of a gamete is RNA. (E) The genetic material of a somatic cell is RNA, whereas the genetic material of a gamete is DNA.

Before we answer our question, let’s go over some of the terms introduced here, starting with DNA. DNA is a biological molecule that stores and transmits genetic information. DNA is also typically transferred to offspring during sexual reproduction by condensing into chromosomes. Sexual reproduction involves two parents, and the offspring inherits DNA from both parents. In sexual reproduction, we want the new offspring to have the same amount of DNA as the parents. So each parent only pass on half of their DNA to each offspring. Notice that both the parent’s cells and the new offspring contain a full set of DNA tightly packed into chromosomes. These cells with two sets of DNA are called somatic cells.

This brings us to more important vocabulary to review. Somatic cells are cells with two sets of chromosomes. Cells that contain two sets of chromosomes are known as diploid. Somatic cells are also called body cells because they make up everything in the body except for cells used for sexual reproduction. So basically, somatic cells are everything in your body except for sperm or egg cells, which are the gametes. We’ll talk about those later. Here, we have an example of a human somatic cell and its nucleus, shown in yellow. Let’s take a closer look at the nucleus.

In the human somatic nucleus, we can see that we have 23 chromosomes from the biological mother, shown in pink, and 23 chromosomes from the biological father, shown in blue. All somatic cells have two sets of DNA, one from each parent. The 23 chromosomes from the biological mother and the 23 chromosomes from the biological father combine to give us the full 46 chromosomes that a human cell needs. When making an offspring, we only want half of the DNA from each parent. This is where the gametes come in.

Gametes are the sex cells, which in humans are the sperm cell or egg cell, depending on if you’re male or female, respectively. Gametes have only one set of chromosomes, which is known as haploid. Gametes are produced during meiosis with the intent of fusing with another gamete to produce a new individual during sexual reproduction. In humans, the human egg cell has 23 chromosomes, and the human sperm cell has 23 chromosomes. They fuse together during sexual reproduction, and this gives human cells the total of 46 chromosomes for our somatic cells. All organisms work this way where their gamete chromosome number should be half of the somatic chromosome number.

We already discussed humans, which have 23 chromosomes in their gametes and 46 chromosomes in their somatic cells. Mice have 20 chromosomes in their gamete. Therefore, they have 40 chromosomes in their somatic cells. Now you try. If a flatworm has eight chromosomes in their gamete, how many chromosomes would we expect in a somatic cell of a flatworm? Because the somatic cell should be double that of the gamete, the flatworm should have 16 chromosomes in its somatic cells. Let’s try that a different way. If corn has 20 chromosomes in its somatic cell, how many chromosomes should there be in the corn’s gamete? You should have found that the corn would have 10 chromosomes in its gamete.

Based on what we’ve learned, we should be able to answer our question. Our question asked, which of the following is correct about somatic cells of an organism and the gametes that the organism produces? The chromosomes in both the somatic cell and a gamete are made of DNA. Therefore, we can eliminate answer choices (D) and (E). We know that gametes are not double the amount of genetic material of the somatic cell, so we can eliminate answer choice (A). We also know that gametes are not 75 percent of the DNA that a somatic cell contains. So we can therefore eliminate answer choice (C). Therefore, the correct answer is answer choice (B). Gametes contain half the genetic material of a somatic cell.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.