Skip to main content
Ch. 3 - Cell Division and Chromosome Heredity
Chapter 3, Problem 4

Cohesion between sister chromatids, as well as tension created by the pull of kinetochore microtubules, is essential to ensure efficient separation of chromatids at mitotic anaphase or in meiotic anaphase II. Explain why sister chromatid cohesion is important, and discuss the role of the proteins cohesin and separase in sister chromatid separation.

Verified step by step guidance
1
Understand the role of sister chromatid cohesion: Sister chromatid cohesion is crucial for maintaining the alignment and proper segregation of chromatids during cell division. It ensures that each daughter cell receives an identical set of chromosomes.
Identify the role of cohesin: Cohesin is a protein complex that holds sister chromatids together after DNA replication. It forms a ring-like structure that encircles the chromatids, maintaining their cohesion until anaphase.
Discuss the role of separase: Separase is an enzyme that becomes active at the onset of anaphase. It cleaves the cohesin complex, allowing sister chromatids to separate and be pulled towards opposite poles of the cell.
Explain the importance of tension: The tension created by kinetochore microtubules pulling on sister chromatids is a signal that ensures proper attachment and alignment before separation. This tension is crucial for the correct timing of separase activation.
Summarize the process: Cohesin maintains chromatid cohesion until anaphase, when separase cleaves cohesin, allowing chromatids to separate. This process is regulated by the tension from microtubules, ensuring accurate chromosome segregation.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Sister Chromatid Cohesion

Sister chromatid cohesion refers to the physical connection between sister chromatids, which are identical copies of a chromosome formed during DNA replication. This cohesion is crucial during cell division, as it ensures that the chromatids remain attached until the appropriate stage of mitosis or meiosis, preventing premature separation and ensuring accurate distribution of genetic material to daughter cells.
Recommended video:

Cohesin Proteins

Cohesin is a protein complex that plays a vital role in maintaining sister chromatid cohesion. It forms a ring-like structure that encircles the chromatids, holding them together from the time of DNA replication until anaphase. The regulated release of cohesin is essential for the proper timing of chromatid separation, ensuring that each daughter cell receives the correct number of chromosomes.
Recommended video:

Separase

Separase is an enzyme that is crucial for the separation of sister chromatids during cell division. It cleaves the cohesin proteins, thereby releasing the chromatids from each other at the onset of anaphase. The activity of separase is tightly regulated to ensure that chromatid separation occurs only when all chromosomes are properly aligned and attached to the spindle apparatus, preventing errors in chromosome segregation.
Related Practice
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

302
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

335
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 prophase I

234
views
Textbook Question

The diploid number of the hypothetical animal Geneticus introductus is 2n = 36. Each diploid nucleus contains 3 ng of DNA in G₁.

Complete the following table by entering the number of chromosomes and amount of DNA present per cell at the end of each stage listed.

End of Cell Cycle      Number of             Amount of
Stage                        Chromosomes       DNA        _
Telophase I
Mitotic telophase
Telophase II

237
views
Textbook Question

The diploid number of the hypothetical animal Geneticus introductus is 2n = 36. Each diploid nucleus contains 3 ng of DNA in G₁.

What amount of DNA is contained in each nucleus at the end of S phase?

303
views
Textbook Question

The diploid number of the hypothetical animal Geneticus introductus is 2n = 36. Each diploid nucleus contains 3 ng of DNA in G₁.

Explain why a somatic cell of Geneticus introductus has the same number of chromosomes and the same amount of DNA at the beginning of mitotic prophase as one of these cells does at the beginning of prophase I of meiosis.

373
views