Table of contents

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

9. Mitosis and Meiosis

Mitosis

Genetics

9. Mitosis and Meiosis

Mitosis

Previous problemNext problem

1:51 minutes

Problem 1b

Textbook Question

How do we know that DNA replication occurs during interphase, not early in mitosis?

Verified step by step guidance

Understand the question: The problem asks us to explain how scientists determined that DNA replication occurs during interphase and not during early mitosis. This involves understanding the experimental evidence and reasoning behind this conclusion.

Step 1: Recall the phases of the cell cycle. The cell cycle consists of interphase (G1, S, and G2 phases) and the mitotic phase (prophase, metaphase, anaphase, and telophase). DNA replication specifically occurs during the S phase of interphase.

Step 2: Review experimental evidence. Scientists used radioactive labeling experiments, such as incorporating tritiated thymidine (a radioactive form of thymine) into newly synthesized DNA. Cells were then observed under autoradiography to determine when DNA synthesis occurred.

Step 3: Analyze the results of these experiments. The radioactive labeling was detected in cells during interphase, specifically in the S phase, but not during mitosis. This provided direct evidence that DNA replication occurs before mitosis begins.

Step 4: Consider the reasoning. For mitosis to proceed correctly, the DNA must already be replicated so that each daughter cell receives an identical set of chromosomes. This functional requirement aligns with the experimental evidence that DNA replication is completed during interphase.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

DNA Replication

DNA replication is the process by which a cell duplicates its DNA before cell division. This occurs during the S phase of interphase, ensuring that each daughter cell receives an identical set of chromosomes. Understanding the timing of DNA replication is crucial for distinguishing between interphase and mitotic phases.

Interphase

Interphase is the phase of the cell cycle where the cell prepares for division, consisting of G1, S, and G2 phases. During interphase, the cell grows, synthesizes proteins, and replicates its DNA. Recognizing interphase as the stage for DNA replication helps clarify why replication does not occur during mitosis.

Mitosis

Mitosis is the process of cell division that results in two genetically identical daughter cells. It is divided into several stages: prophase, metaphase, anaphase, and telophase. Understanding that mitosis follows DNA replication in interphase is essential for grasping the overall cell cycle and the timing of genetic material distribution.

Watch next

Master Mitosis Steps with a bite sized video explanation from Kylia

Start learning

Related Videos

Related Practice

Multiple Choice

In which step is the DNA replicated?

In which step does the chromatin begin to condense

Which checkpoint is responsible for ensuring the DNA was replicated properly?

How do we know that mitotic chromosomes are derived from chromatin?

463

views

Textbook Question

How do we know that chromosomes exist in homologous pairs?

389

views

Textbook Question

Examine the following diagrams of cells from an organism with diploid number 2n=6, and identify what stage of M phase is represented.

497

views

Textbook Question

Our closest primate relative, the chimpanzee, has a diploid number of 2n = 48. For each of the following stages of M phase, identify the number of chromosomes present in each cell.

Mitotic metaphase

465

views

Textbook Question

Our closest primate relative, the chimpanzee, has a diploid number of 2n = 48. For each of the following stages of M phase, identify the number of chromosomes present in each cell.

Early mitotic prophase

437

views

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap