Table of contents

1. Overview of Cell Biology2h 49m
2. Chemical Components of Cells1h 14m
3. Energy1h 33m
4. DNA, Chromosomes, and Genomes2h 31m
5. DNA to RNA to Protein2h 31m
6. Proteins1h 36m
7. Gene Expression1h 42m
8. Membrane Structure1h 4m
- The Lipid Bilayer
  38m
- Membrane Proteins
  25m
9. Transport Across Membranes1h 52m
10. Anerobic Respiration1h 5m
11. Aerobic Respiration1h 11m
12. Photosynthesis52m
13. Intracellular Protein Transport2h 18m
14. Cell Signaling1h 28m
15. Cytoskeleton and Cell Movement1h 39m
16. Cell Division3h 5m
17. Meiosis and Sexual Reproduction50m
18. Cell Junctions and Tissues48m
19. Stem Cells13m
- Stem Cells
  13m
20. Cancer44m
21. The Immune System1h 6m
22. Techniques in Cell Biology1h 41m

4. DNA, Chromosomes, and Genomes

Helical Formations of DNA

Cell Biology

4. DNA, Chromosomes, and Genomes

Helical Formations of DNA

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Multiple Choice

Which of the following property is false regarding supercoiled DNA?

Supercoiling is a helix that has twisted upon itself

Supercoiling can be fixed by topoisomerases

Supercoiling only happens in circular DNA

Supercoiling can happen in both circular and linear DNA

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Verified step by step guidance

Understand the concept of DNA supercoiling: Supercoiling refers to the additional twisting of the DNA double helix. It occurs when the DNA helix twists upon itself, which can happen in both circular and linear DNA molecules.

Recognize the role of topoisomerases: These are enzymes that help manage DNA supercoiling by cutting, twisting, and rejoining DNA strands, thus relieving or introducing supercoils.

Identify the false statement: The statement 'Supercoiling only happens in circular DNA' is false because supercoiling can occur in both circular and linear DNA.

Review the properties of circular and linear DNA: Circular DNA, such as plasmids, naturally exists in a supercoiled state to compact the DNA. Linear DNA, like eukaryotic chromosomes, can also become supercoiled during processes such as replication and transcription.

Conclude by confirming the correct understanding: The false property regarding supercoiled DNA is the claim that it only occurs in circular DNA, as supercoiling is a property that can be observed in both circular and linear DNA forms.