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1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

7. DNA and Chromosome Structure

DNA Structure

Genetics

7. DNA and Chromosome Structure

DNA Structure

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Multiple Choice

Which structure is formed when two DNA strands are twisted around each other?

Nucleosome

Alpha helix

Beta sheet

Double helix

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Verified step by step guidance

Understand the basic structure of DNA: DNA consists of two strands made up of nucleotides, which pair specifically (A with T, and G with C).

Recall that the two DNA strands are not just parallel but twist around each other, forming a specific three-dimensional shape.

Identify the term used to describe this twisted structure: it is known as the 'double helix'.

Differentiate this from other structures: a nucleosome is DNA wrapped around histone proteins, an alpha helix and beta sheet are types of protein secondary structures, not DNA structures.

Conclude that the correct structure formed by two DNA strands twisted around each other is the double helix.