Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 11: Problem 15

List the proteins that unwind DNA during in vivo DNA synthesis. How do they function?

Short Answer

Expert verified
Question: List the proteins that unwind DNA during in vivo DNA synthesis and briefly describe their functions. Answer: The primary proteins involved in unwinding DNA during in vivo DNA synthesis are Helicase, Topoisomerase, and Single-strand binding proteins (SSB). Helicase unwinds the DNA by separating the two strands, Topoisomerase resolves issues caused by overwinding, and SSBs stabilize the single-stranded DNA, ensuring that the replication machinery can access and copy the genetic information.

Step by step solution

01

Identify the primary proteins involved in unwinding DNA

In in vivo DNA synthesis, the proteins that are primarily responsible for unwinding the DNA molecule are Helicase, Topoisomerase, and Single-strand binding proteins (SSB).
02

Understanding the function of Helicase

Helicase is an enzyme that plays a key role in DNA replication by separating the two strands of the double helix. Its primary function is to use ATP to break the hydrogen bonds between the two nucleotide strands, thereby leading to the unwinding of the DNA molecule. Helicase moves along the DNA in a 5' to 3' direction, creating a replication fork.
03

Understanding the function of Topoisomerase

Topoisomerase is an enzyme that helps to manage the supercoiling or overwinding that occurs during the DNA unwinding process. The DNA ahead of the replication fork tends to become overwound, or supercoiled, due to the activity of helicase. Topoisomerase resolves this problem by cutting one or both DNA strands and allowing them to rotate around each other, thereby relieving the tension caused by overwinding. After this, Topoisomerase reseals the DNA strands, allowing the unwinding process to continue smoothly.
04

Understanding the function of Single-strand binding proteins (SSB)

Single-strand binding proteins (SSBs) are small proteins that bind to the separated single-strands of DNA after they are unwound by helicase. They play an essential role in stabilizing the single-stranded DNA and preventing them from reforming the double helix structure, thus allowing the replication machinery to successfully access and copy the genetic information on each strand.
05

Summary

During in vivo DNA synthesis, the proteins responsible for unwinding the DNA molecule are Helicase, Topoisomerase, and Single-strand binding proteins (SSB). Helicase unwinds the DNA by separating the two strands, Topoisomerase resolves issues caused by overwinding, and SSBs stabilize the single-stranded DNA, ensuring that the replication machinery can access and copy the genetic information.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Unlike prokaryotes, why do eukaryotes need multiple replication origins?

In \(1994,\) telomerase activity was discovered in human cancer cell lines. Although telomerase is not active in human somatic tissue, this discovery indicated that humans do contain the genes for telomerase proteins and telomerase RNA. since inappropriate activation of telomerase may contribute to cancer, why do you think the genes coding for this enzyme have been maintained in the human genome throughout evolution? Are there any types of human body cells where telomerase activation would be advantageous or even necessary? Explain.

In this chapter, we focused on how DNA is replicated and synthesized. We also discussed recombination at the DNA level and the phenomenon of gene conversion. Along the way, we encountered many opportunities to consider how this information was acquired. On the basis of these discussions, what answers would you propose to the following fundamental questions? (a) What is the experimental basis for concluding that DNA replicates semiconservatively in both prokaryotes and eukaryotes? (b) How was it demonstrated that DNA synthesis occurs under the direction of DNA polymerase III and not polymerase I? (c) How do we know that in vivo DNA synthesis occurs in the \(5^{\prime}\) to \(3^{\prime}\) direction? (d) How do we know that DNA synthesis is discontinuous on one of the two template strands? (e) What observations reveal that a "telomere problem" exists during eukaryotic DNA replication, and how did we learn of the solution to this problem?

Reiji and Tuneko Okazaki conducted a now classic experiment in 1968 in which they discovered a population of short fragments synthesized during DNA replication. They introduced a short pulse of \(^{3} \mathrm{H}\) -thymidine into a culture of \(E .\) coli and extracted DNA from the cells at various intervals. In analyzing the DNA after centrifugation in denaturing gradients, they noticed that as the interval between the time of \(^{3} \mathrm{H}\) -thymidine introduction and the time of centrifugation increased, the proportion of short strands decreased and more labeled DNA was found in larger strands. What would account for this observation?

Distinguish between (a) unidirectional and bidirectional synthesis, and (b) continuous and discontinuous synthesis of DNA.
See all solutions

Recommended explanations on Biology Textbooks

Communicable Diseases

Read Explanation

Heredity

Read Explanation

Ecosystems

Read Explanation

Genetic Information

Read Explanation

Ecological Levels

Read Explanation

Plant Biology

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free