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Ch. 12 - The Cell Cycle
Campbell - Campbell Biology 12th Edition
Urry12th EditionCampbell BiologyISBN: 9785794169850Not the one you use?Change textbook
Chapter 12, Problem 6

Which of the following occurs during S phase?
a. Condensation of the chromosomes
b. Replication of the DNA
c. Separation of sister chromatids
d. Spindle formation

Verified step by step guidance
1
Understand the cell cycle: The cell cycle consists of interphase (G1, S, G2 phases) and mitotic phase (M phase).
Identify the S phase: The S phase, or synthesis phase, is part of interphase where DNA replication occurs.
Review the options: (A) condensation of the chromosomes occurs during prophase of mitosis, (B) replication of the DNA occurs during the S phase, (C) separation of sister chromatids occurs during anaphase of mitosis, (D) spindle formation begins in prophase of mitosis.
Focus on DNA replication: During the S phase, each chromosome is duplicated, resulting in two sister chromatids for each chromosome.
Conclude the correct answer: Based on the understanding of the S phase, the correct answer is (B) replication of the DNA.

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Key Concepts

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

Cell Cycle

The cell cycle is a series of phases that cells go through to grow and divide. It consists of interphase (G1, S, and G2 phases) and mitotic phase (M phase). Understanding the cell cycle is crucial for identifying when DNA replication occurs, which is during the S phase of interphase.
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S Phase

The S phase, or synthesis phase, is a part of interphase in the cell cycle where DNA replication occurs. During this phase, the cell duplicates its DNA, ensuring that each daughter cell receives an identical set of chromosomes. This is essential for maintaining genetic consistency across cell generations.
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DNA Replication

DNA replication is the process by which a cell duplicates its DNA, producing two identical copies. This occurs during the S phase of the cell cycle and involves unwinding the double helix, using each strand as a template to synthesize new complementary strands, ensuring genetic information is accurately passed on.
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