Problem 8 - Biology: Concepts and Applications

Question

Dogs have a diploid chromosome number of 78. How many chromosomes do their gametes have? a. 39 c. 156 b. 78 d. 234

Step-by-Step Solution

Answer

39 chromosomes in dog gametes.

Step 1: Understanding Diploid Number

The diploid number represents the total number of chromosomes in a somatic cell of an organism. In this case, dogs have a diploid chromosome number of 78.

Step 2: Defining Gametes

Gametes are reproductive cells (such as sperm and eggs) that contain half the number of chromosomes of a typical body cell. This is known as the haploid number.

Step 3: Calculating Haploid Number

To find the number of chromosomes in gametes, divide the diploid number by 2. For dogs: \( \frac{78}{2} = 39 \).

Step 4: Conclusion

The number of chromosomes in a dog's gametes is 39, which corresponds to option a.

Key Concepts

Diploid

In biology, the term "diploid" refers to a cell that contains two complete sets of chromosomes. This is a key characteristic of somatic cells, which make up most of the body's tissues and organs. For dogs, the diploid number is 78, meaning their body cells have 78 chromosomes in total. This number includes paired chromosomes, one set from each parent. The concept of diploidy is central to many biological processes, including growth and maintenance of the organism. It ensures genetic diversity while maintaining the integrity of genetic information.

Understanding diploidy is crucial for grasping how genetic traits are inherited and how organisms develop and grow. Anytime you hear "diploid," think of the total count of chromosomes available in a regular cell, a vital aspect for the organism's functionality and reproduction.

Haploid

While diploid cells contain two sets of chromosomes, haploid cells have just one complete set. This single set signifies half the total number in diploid cells, making haploid cells unique and essential for sexual reproduction. Haploid cells are typically represented in gametes, which are the sperm and egg cells.

The haploid number ensures that when gametes meet during fertilization, the resulting zygote returns to the diploid state. Thus, for dogs with a diploid number of 78, the haploid number is 39, calculated by dividing the diploid number by two.

• Ensures genetic information is halved for reproduction purposes.
• Allows for genetic variation through the combination of maternal and paternal sets of chromosomes.

Knowing the haploid structure helps explain how traits are passed down and how genetic continuity is maintained over generations.

Gametes

Gametes are the special reproductive cells—sperm in males and eggs in females—involved in sexual reproduction. These cells are crucial because they carry half the genetic information compared to somatic body cells. Gametes are unique as they are haploid, containing only one set of chromosomes.

In the case of dogs, their gametes have 39 chromosomes, meaning each parent contributes 39 chromosomes to the offspring. This merging of gametes during fertilization creates a zygote with a full diploid chromosome complement, reintroducing the paired chromosome sets needed for development.

Factors such as genetic diversity and species survival are greatly enhanced by this process. Gamete formation follows a specialized cell division process called meiosis, which ensures genetic variety and correct chromosomal distribution. Understanding gametes sheds light on the fundamental processes that drive sexual reproduction and genetic continuation.