Mutation

The mutation lab utilizes Tetrahymena strains carrying temperature sensitive mutations in genes involved in cell division. At permissive temperatures, the cells are normal, but when shifted to the restrictive temperature, they exhibit easily observed and characterized changes in morphology. This is a clear and simple demonstration of mutations, how temperature sensitive mutations work, and the effects of permissive and restrictive temperature effects in a safe, simple system. The module can be expanded to look at the long and short term effects of exposure to restrictive temperatures and recovery parameters, and can be combined with other modules, to stimulate student development of independent inquiry projects. For more advanced classes, these mutants can also be used as a basis for genetic investigation of dominance and recessiveness, and gene complementation.

Mutation

VIDEOS

“Fat” mutant

(licensed under Creative Commons by-nc-nd 4.0)

 

This cell line carries a temperature sensitive mutation that causes cells grown at a high temperature (restrictive or nonpermissive temperature) (> 37°C ) to become very round and fat, with abnormal swimming patterns, while cells grown at lower temperatures (permissive temperature) (< 32°C) show normal morphology and swimming patterns. Compare the shape and swimming motion of these mutants with the “balloon animal” mutants and the normal cells. “Fat” cells grown at the restrictive temperature can only survive for a few days. A nice discussion of different types of mutations can be found at http://en.wikipedia.org/wiki/Mutation.

“Balloon animal” mutant

(licensed under Creative Commons by-nc-nd 4.0)

 

This cell line carries a temperature sensitive mutation that causes cells grown at a high temperature (restrictive or nonpermissive temperature) (>37°C) to become very misshapen, often forming long protrusions that stick out from the cell. When the cells are grown at lower temperatures (permissive temperature) (<32°C), morphology and swimming patterns are normal. Compare the shape and swimming motion of these mutants with “fat” cells and the normal cells. “Balloon animal” cells grown at the restrictive temperature can only survive for a few days. See the discussion of different types of mutations at http://en.wikipedia.org/wiki/Mutation.

Normal cells

(licensed under Creative Commons by-nc-nd 4.0)

 

Normal Tetrahymena are torpedo shaped cells that swim using multiple rows of cilia along the length of the cell.

Module Protocol

High School

Relevant Concepts

Mutation; Gene regulation; Science as a Process

Next Generation Science Standards Relationships

High School: HS-LS1-1 | HS-LS2-6 | HS-LS3-2 | HS-LS4-3 | HS-LS4-4 | HS-LS4-5

NYS Science Curriculum Guideline Relationships

Key Ideas 1.1 | 1.2 | 1.3 | 4.1 | 4.2 | 4.3 | 4.4

References