Question

Describe Professor Kwang Jeon’s observations of the amoebas and bacteria and explain how this relates to the endosymbiotic theory.

Answer 1

1. Endosymbiosis is the idea that certain organelles found in eukaryotic cells today, like mitochondria and chloroplasts were originally separate organisms which were absorbed into early eukaryotic cells and had a symbiotic relationship with them. Over time, they evolved along with the cells until they were fully part of the cell and no longer self-sufficient organisms.

The best piece of evidence for this theory is that chloroplasts and mitochondria have their own DNA, which is different than the DNA stored in the nucleus. This makes sense since they would have needed their own genetic material when they were independent organisms. Today, though, much of the genetic code controlling mitochondria and chloroplast production and activity has been incorporated into nuclear DNA.

Answer 2

2. They have their on set of genetic information. They have ribosomes attached to them (resembling the size/structure of bacteria) When an organism containing them divides by mitosis they replicate by binary fission and bacteria reproduce this way as well.

Answer 3

3. In 1987, Professor Jeon noticed that his collection of amoeba were developing a large
number of dots. These large number of dots turned out to be bacteria, which were quickly killing off Jeon's collection. Jeon noted the least sick ones and began keeping records of their progress. The least sick ones apparently were more resistant to the bacteria since they survived and returned to their normal modes. However, some 40,000 of the invading bacteria were still present within each of the surviving amoebas! Through transplanting experimentation, Jeon found that the nucleus of the amoebas could live without the once pathogenic bacteria. Jeon's accidental discovery proves that it is possible for an organism to become dependent on and a functional part of invading organisms.