Unit 1 Section 6: Mutations and Cancer

Mutation Germ mutation Somatic mutation Chromosome Deletion Inversion Translocation Nondisjunction Gene mutation	Point mutation Frame-shift Mutagen Teratogen Cancer Oncogene Proto-oncogene Anti-oncogene Carcinogen Tumor	Benign Malignant Metastasize Carcinoma Sarcoma Lymphoma Leukemia Chemotherapy Radiation therapy

Truths about mutations:

Most are minor.
Many are harmful.
Some are lethal.
Very few are helpful.

Which type of mutation are these?  

Germ mutation - occur in gametes.

Somatic mutation - occur in body cells.

Chromosome mutations:

1. Deletion - a piece of a chromosome breaks off and is lost.
2. Duplication - occurs when a gene sequence is repeated in excess of the normal amount.
3. Inversion - a piece of a chromosome breaks off and reattaches itself in reverse order.
4. Translocation - rearrangement of chromosome parts between nonhomologous chromosomes (reciprocal translocation).
5. Non-disjunction - a pair of chromosomes fail to separate during cell division.

A piece of chromosome breaks off and is lost.

A piece of a chromosome breaks off and reattaches in reverse order.

A broken piece attaches to a nonhomologous chromosome.

Nondisjunction is a special chromosome mutation in which a pair of chromosomes fail to separate during cell division.

  Gene mutations:

1. Point mutation or SNP (Single Nucleotide Polymorphism)- a change in a single nitrogen base in DNA. Involves the substitution of a wrong base during the replication process. 
2. Frame-shift mutation - the addition or deletion of one or more nitrogen bases (some number that is not a multiple of three) into a DNA sequence, causing the gene sequence to read out of order.

   Example using a sentence - the letter w is deleted:

   The cow jumped over the moon.
   becomes
   The coj umpedo vert hem oon.

    

  **Short Video on Gene mutations:

• What 3 types of genetic mutations do they discuss in the video?
• How do the mutations affect your DNA?

Mutagen: anything that causes a mutation.

Some well known environmental examples:

Ultraviolet radiation
Tars from tobacco
Asbestos

Teratogen:anything that can cause malformations of an embryo or fetus.

Some examples:

• Arsenic
• Benzene
• Caffeine
• Cannabis
• Ethyl alcohol
• Tobacco

1.6a Assignment - Mutations and Cancer
Scoring criteria

1. Some theories state that mutations are involved in the evolution of life on Earth. Assuming this is true, write a paragraph describing the difference that a somatic mutation and a germ mutation would have on future generations.
2. Do you think chromosome mutations or gene mutations might occur most often? State the reasons for your choice.
3. Chromosome mutations probably occur in which of the four steps of the cell cycle?
4. List three other Teratogen that are not listed on this webpage and give a brief description of each.
5. Explain the difference between a gene mutation and a chromosome mutation?
6. What is melanoma? What causes it?
7. List 3 chemicals found in cigarette smoke that cause cancer.
8. What was Asbestos used for?
9. How would you describe the mutations shown in the pictures linked above.   What type (germ or somatic) of mutations are they? Why?
10. View video on Gene mutations (top of page) and answer the questions here.

Honors biology: complete this section along with the above questions

    1. Using internet resources search and find one disorder in animals caused by a mutation: include

• Name of mutation
• What might be the cause?
• A picture if possible (not all mutations are visible)
• How it effects the organism?

 

Research Links:

• Why so many mutations? - the talk of mutations(evolution).
• Biology 1114 notes on mutations - Oklahoma State University
• Online Mendelian Inheritance in Man - The National Center for Biotechnology Information
• Mutation Rate in E. coli - A paper by Prof. Chuck Holliday, LaFayette College
• What are mutations? - Science at a distance.

A mutation is helpful if it gives the organism an advantage over ones without the mutation.