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

3. Energy & Cell Processes

Introduction to DNA Replication

Anatomy & Physiology

3. Energy & Cell Processes

Introduction to DNA Replication

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Problem 7

Textbook Question

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?a. DNA polymeraseb. DNA ligasec. Okazaki fragmentsd. primase

Verified step by step guidance

Identify the process described: DNA replication.

Understand the issue: DNA molecules have normal strands paired with segments of DNA a few hundred nucleotides long.

Recall the role of each component in DNA replication: DNA polymerase synthesizes new DNA strands, DNA ligase joins Okazaki fragments, Okazaki fragments are short DNA sequences, and primase synthesizes RNA primers.

Recognize that the presence of segments suggests that the short DNA sequences (Okazaki fragments) are not being joined together.

Conclude that the missing component is likely the enzyme responsible for joining these fragments, which is DNA ligase.

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Key Concepts

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

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA, resulting in two identical copies. This process involves several key enzymes and proteins that work together to unwind the DNA double helix, synthesize new strands, and ensure the accuracy of the replication. Understanding the roles of these components is crucial for analyzing any issues that arise during replication.

Okazaki Fragments

Okazaki fragments are short segments of DNA that are synthesized on the lagging strand during DNA replication. They are formed because DNA polymerase can only add nucleotides in a 5' to 3' direction, necessitating the creation of these fragments as the replication fork opens. These fragments must be joined together to form a continuous strand, highlighting the importance of specific enzymes in the replication process.

DNA Ligase

DNA ligase is an essential enzyme that facilitates the joining of Okazaki fragments by forming phosphodiester bonds between adjacent nucleotides. This enzyme is crucial for sealing nicks in the sugar-phosphate backbone of DNA, ensuring the integrity of the newly synthesized strand. If DNA ligase is absent, the replication process will result in incomplete DNA strands, which is likely the issue in the scenario presented.