Concept explainers
A nucleosome consists of (a) DNA and scaffolding proteins (b) scaffolding proteins and histones (c) DNA and histones (d) DNA, histones, and scaffolding proteins (e) histones only
Introduction: A chromosome is a thread-like structure made up of DNA. It is tightly packed in the nucleus of a cell. Humans normally have 23 pairs of chromosomes.
Answer to Problem 1TYU
Correct answer: A nucleosome consists of DNA and histones. Hence, the correct answer is option (c).
Explanation of Solution
Reason for the correct answer:
The nucleosome is the basic unit of chromatin structures. The basic unit of each nucleosome contains a bead-like structure that has 146 DNA base pairs wrapped around the disc-shaped core of eight histone molecules. The nucleosomes prevent the DNA from becoming tangled. Histones play an important part in the regulation of gene expression.
Option (c) is given as “DNA and histones”.
The nucleosome consists of DNA and histones.
Hence, the correct answer is option (c).
Reasons for the incorrect answers:
Option (a) is given as “DNA and scaffolding proteins”.
Nucleosomes consist of DNA, but scaffolding proteins are not present in nucleosomes.
Hence, option (a) is incorrect.
Option (b) is given as “scaffolding proteins and histones”.
Scaffolding proteins are modular proteins that play a crucial role in cell-signaling pathways. Scaffolding proteins are not present in nucleosomes. Histones proteins are present in nucleosomes.
Hence, option (b) is incorrect.
Option (d) is given as, “DNA, histones, and scaffolding proteins”.
Nucleosomes consist of DNA and histones, but scaffolding proteins are not present. Hence, option (d) is incorrect.
Option (e) is given as, “histones only”.
Not only histones, but DNA is also present in the nucleosomes.
Hence, option (e) is incorrect.
Hence, options (a), (b), (d), and (e) are incorrect.
The nucleosome is the basic unit of chromatin structures that consist of DNA and histones.
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Chapter 10 Solutions
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