Difference Between Somatic and Germ Cells

Main Difference – Somatic vs Germ Cells

Somatic cells and germ cells are two basic cell types found in animals. Somatic cells are formed by mitosis during asexual reproduction and germ cells are formed by meiosis during sexual reproduction. Somatic cells are also known as vegetal cells. The main difference between somatic cells and germ cells is that somatic cells are involved in building the body of multicellular animals whereas germ cells are involved in producing haploid gametes, which participate in sexual reproduction. The somatic mutations do not pass through generations since they are not involved in the sexual reproduction. However, mutations in the germ cells pass through generations via sexual reproduction.

Key Areas Covered

1. What are Somatic Cells
      – Definition, Features, Function
2. What are Germ Cells
      – Definition, Features, Function
3. What are the Similarities Between Somatic and Germ Cells
– Outline of Common Features
4. What is the Difference Between Somatic and Germ Cells
– Comparison of Key Differences

Key Terms: Asexual Reproduction, Diploid, Germ Cells, Haploid, Multicellular Animals, Sexual Reproduction, Somatic Cells, Vegetal Cells

What are Somatic Cells

The regular type of body cells is called somatic cells. Typically, somatic cells in humans are diploid and they are produced by mitosis in asexual reproduction. That means, two sets of homologous chromosomes can be found in the nucleus. Some species may consist of haploid or polyploid somatic cells. The polyploid somatic cells are usually found in plants. In humans, the fusion of a sperm cell with the ovum forms the diploid zygote, which is developed into the multicellular organism by continuous mitotic cell divisions. An adult human body has more than three trillion somatic cells. These somatic cells are differentiated into four main types of tissues in the body known as epithelial tissue, connective tissue, muscle tissue, and nerve tissue. Tissues form organs and organs form organ systems.

Figure 1: Muscle fiber cells

Mutations in somatic cells do not contribute to the evolution since they play no role in the sexual reproduction. Cloning is a technique used to produce identical genetic clones of animals. A nucleus of a somatic cell is removed from the cell and injected into an ovum of the same species. The genetic material of the ovum is removed prior to the injection of the somatic cell nucleus. The muscle fiber cells are shown in figure 1. 

What are Germ Cells

A cell that gives rise to the gametes of an organism is referred to as germ cells. Germ cells are originated from the primitive streak of the embryo and they migrate to the gonads through the gut. Germ cells of angiosperms can be found in the floral meristem. The plant germ cells are developed after the embryonic development. The sperm is the male gamete and ovum or egg cell is the female gamete.

Multicellular organisms undergo sexual reproduction through the fusion of gametes. The gametes are haploid cells, which are produced by the meiosis of diploid germ cells. Germ cells are found in gonads; ovaries in females and testes in males. Several rounds of cell divisions occur in germ cells to produce gametes. The production of gametes from germ cells is called gametogenesis. Germ cells undergo both meiosis and mitosis during the production of gametes. The sequence of cells produced from germ cells to gametes is called a germline.

Figure 2: Oogenesis

 Oogenesis is the production of egg cells from germ cells whereas the spermatogenesis is the production of sperm cells. The meiotic division in spermatogenesis results in four, equal spermatids. In contrast, the meiotic division of oogenesis is asymmetrical. A single egg cell is formed while forming three polar bodies. The meiosis in spermatogenesis comprises rapid and uninterrupted cell divisions. But meiosis in oogenesis is interrupted until puberty. Mutations in germ cells pass through generations since they are involved in producing gametes. Oogenesis is shown in figure 2.

Similarities Between Somatic Cells and Germ Cells

• Somatic cells and germ cells are the two types of cells which collectively make up the body of multicellular organisms along with stem cells.
• Both somatic cells and germ cells are diploid in humans. Hence, two sets of homologous chromosomes are found in each somatic and germ cells.
• Both somatic cells and germ cells are capable of differentiating into specific cell types.

Difference Between Somatic Cells and Germ Cells

Definition

Somatic Cells: Somatic cells are any cells in a multicellular organism that are not involved in the production of gametes.

Germ Cells: Germ cells are the cells that create reproductive cells or gametes.

Types

Somatic Cells: Various types of somatic cells are arranged into different types of tissues in the body of multicellular organisms, performing specific functions.

Germ Cells: Germ cells produce male and female gametes.

Amount

Somatic Cells: Majority of the body cells in multicellular organisms are somatic cells.

Germ Cells: Germ cells are very few in number.

Functions

Somatic Cells: Somatic cells perform various functions in the body.

Germ Cells: Germ cells produce gametes, which participate in sexual reproduction.

Cell Division

Somatic Cells: Somatic cells undergo mitosis.

Germ Cells: Germ cells undergo meiosis.

Significance

Somatic Cells: Somatic cells are produced by asexual reproduction.

Germ Cells: Germ cells produce gametes in order to participate in the sexual reproduction.

Mutations

Somatic Cells: Mutations in somatic cells may not pass through the generations.

Germ Cells: Mutations in germ cells pass through the generations.

Effect on Evolution

Somatic Cells: Somatic cell mutations have no effect on evolution.

Germ Cells: Germ cell mutations have an effect on evolution.

Conclusion

Somatic cells and germ cells are two types of cells found in the body of multicellular organisms. Both somatic cells and germ cells are diploid in humans. Diploid germ cells give rise to haploid gametes by meiotic cell divisions. Sperm cells are the male gametes and egg cells are the female gametes. The fusion of a sperm cell with an egg cell produces a diploid zygote, which then proliferates by mitosis to produce a multicellular organism. The majority of body cells of a multicellular organism are somatic cells. Somatic cells undergo asexual reproduction to increase the cell number and cell regeneration. These somatic cells are arranged into tissues, organs, and organ systems in the body, performing specific functions. The main difference between somatic cells and germ cells is their function in the body of a multicellular organism.  

Reference:

“Somatic Cells: Definition, Examples & Types.” Study.com. N.p., n.d. Web. Available here. 15 July 2017.
“Germ Cells in Humans: Definition & Concept.” Study.com. N.p., n.d. Web. Available here. 15 July 2017. 

Image Courtesy:

1. “Diagram of muscle cells CRUK 035” By Cancer Research UK – Original email from CRUK (CC BY-SA 4.0) via Commons Wikimedia
2. “Oogenesis-polar-body-diagram” By Studentreader – Own work (CC BY-SA 3.0) via Common Wikimedia