BACs

Definition

BACs, or Bacterial Artificial Chromosomes, are large DNA constructs derived from bacterial genomes that can be used as vectors for cloning and manipulating large DNA fragments. They serve as important tools in genetic engineering and microbiology research.

5 Must Know Facts For Your Next Test

1. BACs can accommodate DNA inserts of up to 300 kilobases (kb), much larger than the typical 10-15 kb capacity of plasmids.
2. The large insert size of BACs allows for the cloning of entire genes, gene clusters, or even whole operons, facilitating the study of complex genetic systems.
3. BACs are maintained at a low copy number in the host bacterial cell, ensuring the stability of the cloned DNA fragments.
4. BACs can be engineered to contain selectable markers, such as antibiotic resistance genes, allowing for the selection and identification of transformed bacterial cells.
5. The use of BACs has been instrumental in genome sequencing projects, as they provide a reliable way to clone and maintain large DNA fragments for subsequent analysis.

Review Questions

• Explain the advantages of using BACs over plasmids for cloning large DNA fragments.
  • Compared to plasmids, BACs can accommodate much larger DNA inserts, up to 300 kilobases in size. This allows for the cloning of entire genes, gene clusters, or even whole operons, enabling the study of complex genetic systems. Additionally, BACs are maintained at a low copy number in the host bacterial cell, ensuring the stability of the cloned DNA fragments. These features make BACs a superior choice for cloning and manipulating large DNA sequences in genetic engineering and microbiology research.
• Describe how BACs are utilized in genome sequencing projects.
  • BACs have been instrumental in genome sequencing projects due to their ability to reliably clone and maintain large DNA fragments. By creating genomic libraries composed of BAC clones, researchers can systematically sequence and assemble the entire genome of an organism. The large insert size of BACs allows for the cloning of entire genes or gene clusters, facilitating the analysis of complex genetic structures and the identification of important functional elements within the genome.
• Evaluate the role of BACs as tools in genetic engineering and microbiology research.
  • BACs are versatile and powerful tools in the field of genetic engineering and microbiology research. Their ability to accommodate large DNA inserts enables the cloning and study of complex genetic systems, such as entire genes, gene clusters, or operons. This allows researchers to gain a deeper understanding of gene structure, function, and organization. Additionally, the stability of BACs in bacterial hosts and the ability to engineer them with selectable markers make them invaluable for a wide range of applications, including genome sequencing, genetic manipulation, and the construction of genomic libraries. The versatility and capabilities of BACs have significantly advanced our understanding of microbial genetics and facilitated groundbreaking discoveries in the field of microbiology.

Related terms

Plasmids: Small, circular DNA molecules found in bacteria that can replicate independently of the bacterial chromosome and are often used as vectors for genetic engineering.

Cosmids: Hybrid vectors that combine features of both plasmids and bacteriophages, allowing for the cloning of larger DNA fragments than plasmids alone.

Genomic Libraries: Collections of cloned DNA fragments that represent the entire genome of an organism, used for studying gene structure, function, and organization.