3.8: Mutation Causes
- Page ID
- 59262
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Learning Objectives
- Discuss causes of mutation.
- Explain spontaneous mutation.
Causes of Mutation
Mutations have many possible causes. Some mutations seem to happen spontaneously without any outside influence. They can occur when mistakes are made during DNA replication or transcription. Other mutations are caused by environmental factors. Anything in the environment that can cause a mutation is known as a mutagen.
Types of mutagens include radiation, chemicals, and infectious agents. Examples of mutagens are listed in the table below (Table \(\PageIndex{1}\)).. Do you know of other examples of each type of mutagen shown here?
| Mutagen | Type | Examples |
|---|---|---|
| Radiation | UV Radiation | Natural sunlight, tanning beds |
| Radiation | X-rays | Medical, dental, airport security screening |
| Chemical | Cigarette smoke | Active and passive smoke |
| Chemical | Nitrate and nitrate preservatives | Hot dogs and other processed meats |
| Chemical | Benzoyl peroxide | Common ingredient of acne products |
| Infectious agents | Pathogens | HPV and Helicobacter pylori |
Spontaneous Mutations
Mutations are random changes in the sequence of bases in DNA. There are five common types of spontaneous mutations. These are described in the table below (Table \(\PageIndex{2C}\))..
| Mutation | Description |
|---|---|
| Tautomerism | a base is changed by the repositioning of a hydrogen atom |
| Depurination | loss of a purine base (A or G) |
| Deamination | spontaneous deamination of 5-methycytosine |
| Transition | a purine to purine (A to G, G to A), or a pyrimidine to pyrimidine (C to T, T to C) change |
| Transversion | a purine becomes a pyrimidine, or vice versa |
The Chernobyl Disaster: Follow-up
Though the area immediately around the Chernobyl disaster may not be safe for human life for thousands of years, the Exclusion Zone around the Chernobyl nuclear power station has become a haven for wildlife. As humans were evacuated from the area 25 years ago, existing animal populations multiplied and rare species not seen for centuries have returned or have been reintroduced, for example lynx, wild boar, wolf, Eurasian brown bear, European bison, Przewalski's horse, and eagle owl. The Exclusion Zone is so lush with wildlife and greenery that in 2007 the Ukrainian government designated it a wildlife sanctuary. It is now one of the largest wildlife sanctuaries in Europe.
Chapter Summary
- Mutations are caused by environmental factors known as mutagens.
- Types of mutagens include radiation, chemicals, and infectious agents.
- Mutations may be spontaneous in nature.
Review Questions
Use this resource to answer the questions that follow.
Q. What is mutation?
A. Mutations are all the chemical process in the cells.
B. Mutations are random changes in the sequence of bases in DNA.
C. Mutation is a process of cell death.
D. Mutation is a process of protein synthesis.
- Answer:
- B
Critical Thinking Questions
- Define mutation and mutagen.
- List three examples of mutagens.
- Distinguish between a transition and a transversion.
- What happens to most of the mutations that develop naturally?
- Where in the genome do most mutations occur?
- Are most mutations bad? Explain your answer.
- What is meant by DNA repair?
Glossary
- Mutation
- Mutations are random changes in the sequence of bases in DNA
- Mutagen
- Anything in the environment that can cause a mutation is known as a mutagen.