Question

Small loops of nonchromosomal DNA that are found naturally in bacteria are called a. plasmids. b. primers. c. vectors. d. clones.

Short answer

a. plasmids.

Step-by-step solution

Understand the Question

The question asks about small loops of nonchromosomal DNA found naturally in bacteria and requests identification of the correct term from multiple choices.

Recall Key Concepts

Recall that bacteria can contain extra-chromosomal DNA in small loops, which have unique roles, such as carrying genes that provide special functions like antibiotic resistance.

Evaluate Each Option

Consider each term: - Plasmids: Known to be small, circular DNA in bacteria, involved in genetic functions. - Primers: Short strands of RNA or DNA that serve as a starting point for DNA synthesis. - Vectors: Vehicles used to transfer genetic material to cells, can include plasmids but are not inherently small DNA loops themselves. - Clones: Genetically identical cells or organisms, not related to small DNA loops.

Select the Correct Answer

Given the definitions, the term that matches small loops of nonchromosomal DNA found naturally in bacteria is 'plasmids'.

Key concepts

Nonchromosomal DNA

In the world of genetics, understanding where DNA is located is essential. While most people think of DNA within the chromosomes in the nucleus, bacteria have another type known as nonchromosomal DNA. This DNA exists outside of the bacterial chromosome and plays crucial roles within the bacterial cell. One of the primary forms of this nonchromosomal DNA is known as plasmids.
Plasmids are small, circular, double-stranded DNA molecules. Unlike chromosomal DNA, which houses the essential genes for bacterial survival, plasmids carry genes that provide additional functions. These can include:

• Antibiotic resistance
• Virulence factors (helping bacteria infect hosts)
• Metabolic processes (breaking down unusual substances)

Bacteria can have multiple plasmids and, interestingly, they can share plasmids with other bacteria through a process called conjugation. This horizontal gene transfer is one reason why bacterial populations can quickly adapt to new environments.

Genetic Functions

The genetic functions of plasmids extend beyond merely existing as loops of DNA. They serve as genetic tools enabling bacteria to adapt and thrive under various conditions. Plasmids can carry genes that perform specialized functions that aren't typically encoded by the bacterial chromosome.
Here's how plasmids contribute to genetic functions:

• **Antibiotic Resistance Genes:** These genes enable bacteria to survive despite the presence of antibiotics. Given our increasing reliance on antibiotics, the role of plasmids in spreading resistance is critical.
• **Biodegradation:** Some plasmids have genes that help bacteria digest and break down a variety of organic compounds, aiding in environments that have certain detoxification processes.
• **Pathogenicity:** Plasmids can carry genes that make a bacterium more virulent or better able to cause disease. This attribute is especially notable in studying bacterial infections and developing treatments.

Additionally, in biotechnology and genetic engineering, scientists utilize plasmids extensively. They harness plasmids to insert specific genes into bacterial cells intentionally, making these cells produce desired products, such as insulin or other medications.

Antibiotic Resistance

Antibiotic resistance is a significant medical concern globally, and plasmids play a pivotal role in this issue. Genes that provide resistance to antibiotics are often located on plasmids. These plasmids can then be transferred between bacteria, spreading resistance traits rapidly across bacterial populations.

• **Mechanisms of Resistance:** Bacteria can become resistant through several mechanisms. These can include producing enzymes that deactivate antibiotics, altering their cell walls to prevent antibiotic entry, or using efflux pumps to remove the antibiotic from the cell.
• **Transfer of Resistance Genes:** Plasmids facilitate the process known as horizontal gene transfer. Unlike vertical gene transfer that occurs during reproduction, horizontal transfer allows bacteria to share genetic material directly. This enables even unrelated bacterial species to acquire resistance genes.
• **Real-world Implications:** The spread of antibiotic-resistant bacteria is alarming, leading to infections that are harder to treat and control. It highlights the need for careful use of antibiotics and significant research into alternative treatments.

Understanding plasmids and the role they play in resistance informs both the creation of more effective treatments and the development of strategies to mitigate this pressing health issue.