what is the relationship between primitive bacteria and modern mitochondria and chloroplasts?

Question

2. Present an overview of two classical experiments which demonstrated that DNA is the genetic material. Also, can RNA be the genetic material? Explain.


I don't no how to answer this.. any1 can help? thank you u advance..

Answer 1

Modern mitochondria/chloroplasts are very similar; this has let to the widely accepted theory of endosymbiosis, which says that mitochondria/chloroplasts actually were bacteria who were engulfed by larger bacteria and live inside them. Mitochondria/chloroplasts have their own circular DNA molecule, just like bacteria, and they have ribosomes which resemble bacterial ribosomes, and they reproduce by binary fission just like bacteria. Basically, mitochondria and chloroplasts are virtually bacterica that have gone a few changes over the ages from living inside the larger eukaryotic cells.

One classical experiment was the Griffith experiment; this said that some kind of chemical serves as the element of heridity, because living harmless bacteria could be transformed into pathogenic strains from mixing them with dead pathogenic bacteria.

Another one was teh Hershey-Chase experiment. This one proved that it was not protein which was the genetic material (which was widely believed to be true at the time), but rather was DNA that served as the genetic material.

RNA could be the genetic material, and RNA most likely was the first genetic material. However, RNA is highly unstable due to the presense of an extra oxygen atom, and thus it's role of being the genetic material has been taken over by the far more stable DNA.

Answer 2

1-There's a theory that modern mitochondria and chloroplasts evolved from primitive aerobic or photosynthetic bacteria. An anaerobic cell *accidentally* engulfed a bacterium, and it happened to be at the time when oxygen and/or sunlight were becoming more efficient sources of energy. Process of natural selection, and cells with double membrane bound chloroplasts and mitochondria evolved. Evidence which supports this includes the fact that the mitochondria and chloroplasts are membrane bound, they have their own DNA, and they have their own ribosomes.

2-Look up Hershey Chase experiment and Oswald Theodore Avery experiment on wikipedia or google. Yes, RNA can be genetic material. There are viruses which carry only RNA in their protein capsids. Once they have injected their RNA into a bacterium, they use reverse transcriptase to make DNA, then carry out the same transcription translation process as normal.