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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

How are the two strands of DNA held together in a double helix?

By hydrogen bonds between complementary nitrogenous bases

By covalent bonds between phosphate groups

By disulfide bridges between nucleotides

By ionic interactions between sugar molecules

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Verified step by step guidance

Recall the structure of DNA, which consists of two strands forming a double helix.

Understand that each strand is made up of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.

Recognize that the backbone of each strand is held together by covalent bonds between the sugar and phosphate groups, but these bonds do not hold the two strands together.

Focus on the interaction between the nitrogenous bases of the two strands: complementary bases pair specifically (adenine with thymine, guanine with cytosine).

Identify that the two strands are held together by hydrogen bonds formed between these complementary nitrogenous bases, stabilizing the double helix structure.