Transposable Elements: Types, Function, and Examples in AP Biology

📚 Quick Study Guide

• 🧬 Transposable Elements (TEs): Also known as jumping genes, are DNA sequences that can change their position within a genome.
• 🧩 Types of TEs:
  • I. Class I (Retrotransposons): Transpose through an RNA intermediate. 'Copy and paste' mechanism.
  • II. Class II (DNA Transposons): Transpose directly as DNA. 'Cut and paste' or 'copy and paste' mechanism.
• ⚙️ Retrotransposons:
  • 🔑 Long Terminal Repeats (LTRs): Resemble retroviruses.
  • 🗝️ Non-LTRs: Include LINEs (Long Interspersed Nuclear Elements) and SINEs (Short Interspersed Nuclear Elements).
• ✂️ DNA Transposons:
  • 📍 Autonomous: Encode their own transposase enzyme.
  • 📌 Non-autonomous: Require transposase from another transposon.
• 🔬 Function:
  • 🌱 Genetic Variation: Contribute to mutations and genome plasticity.
  • 🛡️ Gene Regulation: Can influence gene expression.
  • 🚧 Genome Evolution: Play a role in genome size and structure.
• 🌱 Examples:
  • 🌽 Ac/Ds system in Maize: A classic example of autonomous and non-autonomous DNA transposons.
  • 👨‍🔬 LINE-1 elements in humans: A type of retrotransposon that can cause insertional mutagenesis.

🧪 Practice Quiz

1. Which of the following best describes a transposable element?
   1. A. A segment of DNA that can change its position within a genome.
   2. B. A type of restriction enzyme.
   3. C. A structural component of the ribosome.
   4. D. A protein involved in DNA replication.
2. What is the primary difference between Class I and Class II transposable elements?
   1. A. Class I elements transpose as DNA, while Class II elements transpose through an RNA intermediate.
   2. B. Class I elements transpose through an RNA intermediate, while Class II elements transpose as DNA.
   3. C. Class I elements are found only in prokaryotes, while Class II elements are found only in eukaryotes.
   4. D. Class I elements are smaller than Class II elements.
3. Which type of transposable element utilizes a 'copy and paste' mechanism involving an RNA intermediate?
   1. A. DNA transposons
   2. B. Retrotransposons
   3. C. Autonomous transposons
   4. D. Non-autonomous transposons
4. What is the role of transposase in transposition?
   1. A. It is an RNA molecule that guides the transposon to its new location.
   2. B. It is an enzyme that catalyzes the movement of the transposon.
   3. C. It is a structural protein that protects the transposon from degradation.
   4. D. It is a regulatory protein that controls the expression of genes near the transposon.
5. LINEs and SINEs are examples of what?
   1. A. LTR retrotransposons
   2. B. Non-LTR retrotransposons
   3. C. DNA transposons
   4. D. Autonomous transposons
6. Which of the following is a potential consequence of transposable element insertion into a gene?
   1. A. Increased gene expression
   2. B. Decreased gene expression
   3. C. Gene disruption
   4. D. All of the above
7. In the Ac/Ds system in maize, what is the role of the Ac element?
   1. A. It is a non-autonomous element that requires the Ds element for transposition.
   2. B. It encodes the transposase enzyme necessary for the transposition of both Ac and Ds elements.
   3. C. It inhibits the transposition of the Ds element.
   4. D. It is a type of retrotransposon.