BACs and YACs are:

Options

A. Natural DNA obtained from bacteria and
B. Useful vectors for eukaryolic gene transfer
C. Artificial DNA obtained from bacteria and yeast
D. Both b and c

Answer

**Step-by-Step Text Solution:**

1. **Understanding BACs and YACs:**
- BAC stands for Bacterial Artificial Chromosome, while YAC stands for Yeast Artificial Chromosome. Both are types of vectors used in genetic engineering.

2. **Function and Capacity:**
- BACs can carry approximately 195 kilobases (KB) of DNA, making them suitable for cloning larger DNA fragments.
- YACs can carry even larger DNA inserts, approximately 450 KB, which allows for the cloning of very large genes or genomic fragments.

3. **Source of BACs and YACs:**
- Both BACs and YACs are artificial constructs. They are not naturally occurring but are engineered in laboratories.
- BACs are derived from bacterial cells, while YACs are derived from yeast cells.

4. **Applications:**
- Both BACs and YACs are primarily used for cloning and transferring genes, particularly in eukaryotic systems. They are useful for gene mapping and sequencing projects.

5. **Conclusion:**
- The correct answer to the question is that BACs and YACs are "Useful vectors for eukaryotic gene transfer" and "Artificial DNA obtained from bacteria and yeast." Therefore, the correct option is both B and C.