AP Biology Questions on Restriction Enzymes and Plasmids

📚 Quick Study Guide

• ✂️ Restriction enzymes are proteins that cut DNA at specific sequences called restriction sites.
• 🧬 Plasmids are small, circular DNA molecules found in bacteria and some other microscopic organisms. They are often used as vectors to carry foreign DNA into a host cell.
• 🧫 Recombinant DNA is formed when DNA fragments from different sources are joined together. Restriction enzymes and plasmids are essential tools in creating recombinant DNA.
• 🧪 DNA ligase is an enzyme that joins DNA fragments together by catalyzing the formation of phosphodiester bonds.
• 🔢 Restriction enzymes produce fragments with either sticky ends (overhanging single-stranded DNA) or blunt ends (double-stranded DNA). Sticky ends are useful for creating recombinant DNA because they can easily anneal with complementary sticky ends.
• 💡 Plasmids used in cloning typically contain: an origin of replication (ori), an antibiotic resistance gene (e.g., ampicillin resistance), and a multiple cloning site (MCS) where restriction enzymes can cut.
• 🔬 Transformation is the process by which bacteria take up foreign DNA, such as a plasmid.

🧪 Practice Quiz

1. Which of the following enzymes is used to join DNA fragments together?
   1. DNA polymerase
   2. Restriction enzyme
   3. DNA ligase
   4. RNA polymerase
2. What is a plasmid?
   1. A type of restriction enzyme
   2. A small, circular DNA molecule found in bacteria
   3. A linear fragment of DNA
   4. A type of RNA
3. What is the function of a restriction enzyme?
   1. To replicate DNA
   2. To cut DNA at specific sequences
   3. To join DNA fragments together
   4. To transcribe DNA into RNA
4. What is recombinant DNA?
   1. DNA that has been cut into small fragments
   2. DNA that has been replicated many times
   3. DNA formed by joining fragments from different sources
   4. DNA that has been transcribed into RNA
5. What is a 'sticky end'?
   1. A DNA fragment with a blunt end
   2. A DNA fragment with overhanging single-stranded DNA
   3. A DNA fragment that is difficult to ligate
   4. A DNA fragment that is resistant to restriction enzymes
6. Which of the following is typically found on a plasmid used in cloning?
   1. A promoter sequence only
   2. An origin of replication, an antibiotic resistance gene, and a multiple cloning site
   3. A ribosome binding site only
   4. A terminator sequence only
7. What is transformation in the context of bacterial genetics?
   1. The process by which bacteria divide
   2. The process by which bacteria take up foreign DNA
   3. The process by which bacteria exchange DNA through conjugation
   4. The process by which bacteria mutate their DNA