Table of contents

Skip topic navigation

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

Previous problemNext problem

Struggling with Genetics?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

Which is the most accurate statement about the DNA double helix?

The two strands are antiparallel and held together by hydrogen bonds between complementary bases.

The double helix consists of two identical strands running in the same direction.

Adenine pairs with cytosine through three hydrogen bonds.

The sugar-phosphate backbones are located on the inside of the helix.

Previous problemNext problem

Verified step by step guidance

Understand the structure of the DNA double helix: DNA consists of two strands that form a helical shape.

Recall that the two strands run in opposite directions, meaning they are antiparallel. This means one strand runs 5' to 3' and the other runs 3' to 5'.

Recognize that the strands are held together by hydrogen bonds between complementary nitrogenous bases: adenine pairs with thymine, and cytosine pairs with guanine.

Remember the base pairing rules: adenine pairs with thymine via two hydrogen bonds, and cytosine pairs with guanine via three hydrogen bonds.

Note the position of the sugar-phosphate backbone: it is located on the outside of the helix, providing structural support, while the bases are on the inside forming the rungs of the ladder.