Could Extraterrestrial Life Look Like An Extremophile?

Overview & Concepts

Astrobiologists are interested in the salt-loving Archaen, Halobacterium sp. NRC-1, for the possibility that similar life forms could exist on Mars.  Halobacterium live in high salinity and temperatures ranging from -7 to 27C.  Halite has been discovered in meteorites from Mars and salt also provides some protection from UV light  suggesting that Halobacterium can model a Martian lifeform. 

Students use bioinformatics (ClustalW) to compare the Halobacterium cytochrome c oxidase subunit I DNA sequence with that of up to 9 other species.  They observe similarities and differences in codes and consider possible phylogenies.   Then students use the Carolina Biological Supply Co. kit, “Introduction to Life in an Extreme Environment,” to grow Halobacterium from salt crystals, observe the organisms and design an experiment to study effects of changes in the extremophile environment.

Grade Level: 

Concepts Covered: 

Genetics,  DNA sequence,  Microscopy,  Scientific Method,  Taxonomy 

Prior Knowledge Required: 

Knowledge of DNA, descent of species and scientific method.

Activity Notes

Days to Teach: 

Bioinformatics activity: 1 day. Halobacterium research: Will vary depending on Halobacterium incubation time (2 weeks @ room temperature, 7 days at 47 degrees C.) and depth of investigation; intervening days could be used for other activities..


Computers with internet access,  Carolina Biological Supply Co. "Introduction to Life in an Extreme Environment" kit #15-4770,  Microscopes, Test tube racks,  Incubator (to reduce growth time)

Teaching Tips / Activity Overview: 

  1. Background – Astrobiologists are interested in Halobacterium for the possibility that they could exist on Mars.
  2. Using bioinformatics and Carolina Biological Supply Co. kit, “Introduction to Life in an Extreme Environment,” students will learn that diversity on life includes life forms that survive in extreme conditions on Earth and possible could exist in similar extraterrestrial environments.
  3. From an assortment of DNA sequences provided for comparison (including pictures of organisms) students choose 5 in addition to Halobacterium to use Clustal alignment and tree. (eg.) 
  4. Students draw their tree and answer questions.
  5. Proceed to the Carolina Biological Supply Company kit: 15-4770: Introduction to Life in an Extreme Environment Teacher's Manual with Student Guide. The kit includes most materials needed, instructions for teacher and student worksheets. 



Students will be assessed on worksheet completion and data collection and conclusions from Halobacterium research.



Richard Pool wrote this activity.

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