Chapter 12, Problem 33A

Summary Introduction

To write:

Correct vocabulary that describes the given process

Introduction:

Sometimes there is an error during replication of DNA. These are rare and the cells have repair mechanisms that can repair some of the damage. Sometimes these changes are permanent and the DNA does not code for the same protein any longer.

Answer to Problem 33A

Mutation

Explanation of Solution

A permanent change in the cell’s DNA is called mutation. This change occurs in the nucleotide sequence in DNA. It can be caused by errors in replication, transcription, cell division or by some external agents.

Mutations can occur in single base pair or a large section of DNA may be deleted. Point mutation in one base pair may cause genetic disorder. There are many types of point mutations; missence and nonsense mutations. Insertions occur when a nucleotide is added to the DNA sequence. Deletion occurs when a nucleotide is removed from a DNA sequence.

A new kind of mutation was discovered in 1991 that involves an increase in number of copies of repeated codons called tandem repeats. This caused many disorders such as fragile X syndrome.