Friday, April 1, 2011

Endosymbiotic Origins

Eukaryotic Cell
Prokaryotic Cell
      There are two basic types of cells found in organisms, prokaryotic cells and eukaryotic cells. Prokaryotic cells are those found in bacteria and archaea, while protists, fungi, animals, and plants are composed of eukaryotic cells. One of the main differences between these two types of cells is that chromosomes are located in the membrane-bound nucleus in eukaryotes and in a non-enclosed area known as the nucleoid in prokaryotes. Eukaryotes also contain other membrane-bound organelles while prokaryotes do not. Endosymbiotic theory posits that these membrane-bound organelles were originally small prokaryotes that were engulfed by larger predatorial cells.
     There is a large amount of evidence in support of this theory. For example, both mitochondria and chloroplasts have their own DNA which is found in one circular molecule not associated with histones. These organelles also have their own transfer RNAs, ribosomes, and other molecules needed for transcription and translate. Also, mitochondria and chloroplasts both divide in a process more similar to that of binary fission which occurs in prokaryotes. Mitochondria and chloroplasts have ribosomes which are more similar to prokaryotic ribosomes in terms of nucleotide sequence, size, and antibiotic sensitivities.
     You might be wondering how and why this would happen. As far as how, the smaller prokaryotic cells most likely entered the eukaryotic cells as internal parasites or undigested prey. From there a mutual relationship developed, benefiting both cells. The smaller cells gained protection in an increasingly oxygen enriched environment from the eukaryotic host, while the host was able to use nutrients from the photosynthetic prokaryote. Both cells became increasingly dependent on the benefits gained from the relationship until they were no longer separate organisms.


  1. I always enjoyed this concept, but forgot about it until the practice GRE. Thanks for the refresher!

  2. I have been suffering from (HERPES) disease for the last four years and had constant pain, especially in my knees. During the first year, I had faith in God that I would be healed someday.This disease started to circulate all over my body and I have been taking treatment from my doctor, a few weeks ago I came on search on the internet if I could get any information concerning the prevention of this disease, on my search I saw a testimony of someone who has been healed from (Hepatitis B and Cancer) by this Man Dr.Ekpiku and she also gave the email address of this man and advise we should contact him for any sickness that he would be of help, so I wrote to Dr.Ekpiku telling him about my (HERPES Virus) he told me not to worry that I was going to be cured!! hmm i never believed it,, well after all the procedures and remedy given to me by this man few weeks later I started experiencing changes all over me as the Dr. assured me that I have cured, after some time i went to my doctor to confirmed if I have been finally healed behold it was TRUE, So friends my advice is if you have such sickness or any other at all you can email Dr.Ekpiku or text/call me +16506538578 for more infor.