Model Organisms

Geneticists have identified certain model organisms which are useful for studying genetic processes in cells. Among the bacteria, E. coli, which is commonly found in the mammalian intestinal tract, has been one of the most widely studied species due to its genetic simplicity and the ease with which it may be grown in the laboratory. Bacillus subtilis, typically found in soil environments, has also been intensively studied because of its tolerance for genetic modification and its ability to produce commercially available biochemicals. Among plants, Arabidopsis thaliana, a mustard weed, has been selected as a model organism due to its high reproductive rate and relatively small genome size. These features make this small weed simpler to genetically manipulate than more complex plant species. Within the Fungi kingdom, the bread mold Neurospora crassa has been chosen as a representative organism because its haploid genome allows the effects of mutations in its DNA to be directly observed. In addition, Neurospora’s short life cycle is useful for efficiently studying patterns of genetic inheritance. Baker’s yeast, or Saccharomyces cerevisiae, is another model organism that has been valuable to genetic research. Yeast is an advantageous organism to study because it is a simple, unicellular eukaryote that is easy to grow and genetically manipulate. Among animals, the fruit fly Drosophila melanogaster is used as a model organism mainly due to its short life cycle and high reproductive rate. Because of these attributes, the inheritance of genetic traits and mutations in this organism can be traced through many generations in a relatively short period of time. Another useful animal model is the mouse. Recently developed techniques allow scientists to breed mice with intentionally engineered mutations in particular genes. By tracking the effect of these mutations, it is possible to identify why certain genes are required and what functions they serve. Finally, the worm C. elegans has been chosen as a developmental model because it is a transparent organism where all cells are visible when viewed under a microscope. This feature is useful because it allows researchers to directly observe changes in the growth patterns of individual cells. Among archaea and extremophilic bacteria – those which grow in extremely salty or high temperature environments - Halobacteria are good model organisms because they are easy to culture and manipulate in the laboratory. Furthermore, the biochemical machinery of archaea resembles that of eukaryotes and could therefore be useful in understanding the workings of higher organisms.

Question 1: Among the bacteria, which organism is commonly used in the laboratory and also easy to study due to its simplicity?
  1. E. coli
  2. Yeast
  3. Drosophila melanogaster
  4. C. elegans


Answer 1

Answer - (a) E. coli

Question 2: Bacillus subtilis, typically found in soil environments, has also been intensively studied because of its ability to produce which commercially useful products?
  1. Biochemicals
  2. Petrochemicals
  3. Biometals
  4. Blood chelators


Answer 2

Answer - (a) Biochemicals

Question 3: Why is Arabidopsis thaliana, mustard weed, a model organism among plants?
  1. Because of its small genome size
  2. Because of its fast generation time
  3. Because of the facile genetic manipulation methods developed for it
  4. Because of its small genome size and fast generation time


Answer 3

Answer - (d) Because of its small genome size and fast generation time

Question 4: True or False? Within the Fungal kingdom, the bread mold Neurospora crassa has been chosen as a representitive organism because its haploid genome allows the effects of mutations in its DNA to be directly observed phenotypically.
  1. True
  2. False


Answer 4

Answer - (b) True

Question 5: Yeast is a unicellular ____________.
  1. prokaryote
  2. eukaryote
  3. fungus
  4. bacterium


Answer 5

Answer - (b) eukaryote

Question 6: The inheritance of the genetic traits and mutations in Drosophila melanogaster can be traced through many generations mainly because of its _________.
  1. Short life cycle
  2. Fast generation time
  3. Genetic manipulation methods
  4. All of the above


Answer 6

Answer - (d) All of the above

Question 7: What is special about C. elegans as a model organism?
  1. Its small genome size
  2. Its fast generation time
  3. Its genetic manipulation tools
  4. Its transparent body


Answer 7

Answer - (d) Its transparent body

Question 8: Why are Halobacteria useful models for studying higher organisms?
  1. The ease of culturing them
  2. The well-developed genetic manipulation methods
  3. Their homology to the eukaryotic biochemical machinery
  4. All of the above


Answer 8

Answer - (d) All of the above