Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Nucleic Acids

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Nucleic Acids

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Problem 7

Textbook Question

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?a. 5′-AGCT-3′ with 5′-TCGA-3′b. 5′-GCGC-3′ with 5′-TATA-3′c. 5′-ATGC-3′ with 5′-GCAT-3′d. All of these pairs are correct.

Verified step by step guidance

Step 1: Understand that DNA is a double helix structure, where two strands are held together by hydrogen bonds between pairs of nucleotides. The pairs are always adenine (A) with thymine (T), and guanine (G) with cytosine (C).

Step 2: Remember that DNA strands are antiparallel, meaning one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction.

Step 3: Evaluate each option by comparing the base pairs. They should be complementary (A with T, G with C) and the sequences should be in reverse order due to the antiparallel nature of DNA strands.

Step 4: For option a, the sequences are 5′-AGCT-3′ and 5′-TCGA-3′. These are complementary and in reverse order, so they could form a DNA double helix.

Step 5: For option b, the sequences are 5′-GCGC-3′ and 5′-TATA-3′. These are not complementary, so they could not form a DNA double helix.

Step 6: For option c, the sequences are 5′-ATGC-3′ and 5′-GCAT-3′. These are complementary but not in reverse order, so they could not form a DNA double helix.

Step 7: Therefore, only option a could form a short stretch of a normal double helix of DNA.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Base Pairing Rules

Base pairing rules dictate how nucleotides in DNA pair with each other. Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G). This complementary base pairing is essential for the formation of the double helix structure of DNA, ensuring accurate replication and transcription.

DNA Structure

DNA is structured as a double helix, consisting of two strands that run in opposite directions (antiparallel). Each strand is composed of a sugar-phosphate backbone and nitrogenous bases. The specific orientation of the strands (5' to 3' directionality) is crucial for understanding how base pairs align and interact within the helix.

Nucleotide Sequences

Nucleotide sequences refer to the specific order of nucleotides in a DNA strand. The sequence determines the genetic information carried by the DNA. In the context of the question, evaluating whether the given pairs of sequences can form a double helix involves checking for complementary sequences that adhere to the base pairing rules.