Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 11: Problem 9

What are the molecular composition and arrangement of the components in the nucleosome?

Short Answer

Expert verified
Short Answer: Nucleosomes are composed of histone proteins and DNA. They contain a histone octamer with two copies of core histone proteins (H2A, H2B, H3, and H4), around which 146 base pairs of DNA are wrapped in a left-handed superhelical turn. Histone H1 acts as a linker by binding to the linker DNA and the nucleosome core, helping stabilize the structure. The organization of nucleosomes in chromatin fibers allows DNA compaction, protection, and regulation of gene expression.

Step by step solution

01

1. Components of Nucleosomes

Nucleosomes are the fundamental units of DNA packaging in the eukaryotic cell and consist of two main components: histone proteins and DNA.
02

2. Histone proteins

Histone proteins play a crucial role in nucleosome structure. A nucleosome is made up of 8 histone proteins, forming a histone octamer. This octamer comprises two copies of each core histone proteins H2A, H2B, H3, and H4.
03

3. DNA wrapping

About 146 base pairs of DNA are wrapped around the histone octamer core in a left-handed superhelical turn. This organization allows the DNA to be compacted and protects it from damage.
04

4. Histone H1

Histone H1 is known as a linker histone, which is not a part of the histone octamer core. Still, it plays a role in stabilizing nucleosome structure by binding to the linker DNA and the nucleosome core. Linker DNA is the segment of DNA between two adjacent nucleosomes.
05

5. Chromatin fiber

Nucleosomes are organized like beads on a string, with each nucleosome connected by linker DNA and histone H1. The string of nucleosomes can then be further compacted into a chromatin fiber.
06

6. Importance of nucleosome structure

Nucleosome structure is essential for its function, as it allows DNA to be compacted, reducing its length inside the nucleus. The organization also regulates access to the genetic information, allowing specific genes to be turned on or off by remodeling nucleosomes or modifying histone proteins.

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

What genetic process is occurring in a puff of a polytene chromosome?

During what genetic process are lampbrush chromosomes present in vertebrates?

In this chapter, we focused on how DNA is organized at the chromosomal level. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, propose answers to the following fundamental questions: (a) How do we know that viral and bacterial chromosomes most often consist of circular DNA molecules devoid of protein? (b) What is the experimental basis for concluding that puffs in polytene chromosomes and loops in lampbrush chromosomes are areas of intense transcription of RNA? (c) How did we learn that eukaryotic chromatin exists in the form of repeating nucleosomes, each consisting of about 200 base pairs and an octamer of histones? (d) How do we know that satellite DNA consists of repetitive sequences and has been derived from regions of the centromere?

Why might we predict that the organization of eukaryotic genetic material will be more complex than that of viruses or bacteria?

Contrast the structure of SINE and LINE DNA sequences. Why are LINEs referred to as retrotransposons?
See all solutions

Recommended explanations on Biology Textbooks

Cellular Energetics

Read Explanation

Substance Exchange

Read Explanation

Biological Structures

Read Explanation

Genetic Information

Read Explanation

Microbiology

Read Explanation

Cells

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