hi I'm Kathy with love Larn in this video I will be discussing the endosymbiotic theory and at the end of the video I'm going to give you guys a quiz to test your understanding of some of the key points I'll be covering so definitely stay tuned till the end of the video and if you have our level up RN microbiology flashcards go ahead and pull out your flashcards on endosymbiotic Theory so you can follow along with me the endosymbiotic theory explains how certain organel in particular mitochondria and chloroplast evolved from procaryotic cells the mitochondrian is an organel in a eukaryotic cell where aerobic cellular respiration occurs the endosymbiotic theory states that this organel originally arose when a bacterium capable of aerobic cellular respiration was taken into a eukaryotic cell via phagocytosis and then remained in the cell as an intracellular component this Theory also applies to chloroplasts which are organel found in some eukaryotic cells such as plant cells and algae cells the chloroplast is where photosynthesis occurs and the endosymbiotic theory states that this organel originally arose when a bacterium capable of photosynthesis was taken into a eukaryotic cell via phagocytosis and then remained in that cell as an intracellular component there are several key pieces of evidence that support endosymbiotic Theory first of all the DNA in mitochondria and chloroplast is circular which is the same as procaryotic or bacterial cells but is different than UK carotic cells which contain DNA in linear chromosomes the next piece of evidence is the fact that the ribosomes found in mitochondria and chloroplasts are 70s ribosomes which is the same as procaryotic ribosomes but is different than eukaryotic ribosomes which are ads ribosomes mitochondria and chloroplast are small in size just like procaryotic cells whereas eukaryotic cells are larger in size mitochondria and chloroplast divide by binary fish just like procaryotes whereas eukaryotic cells divide by mitosis and finally mitochondria and chloroplast have a double membrane and the composition of the inner membrane is similar to the composition of a procaryotic plasma membrane whereas the composition of the outer membrane is more similar to a eukariotic plasma membrane which suggests that when the bacterium was taken up via phagocytosis the host cells plasma membrane wrapped around the bacterium and this became the outer membrane of the organel all right it's quiz time and I have three questions for you question number one the presence of which two organel in a eukaryotic cell can be explained by the endosymbiotic theory the answer is mitochondria and chloroplast number two how do the ribosomes in a chloroplast support endosymbiotic Theory the answer is the ribosomes in a chloroplast are 70s ribosomes which are the same as the ribosomes found in a procaryotic Cell question number three the inner membrane of a mitochondrian is similar in composition to the plasma membrane of a eukaryotic cell true or false the answer is false it is similar in composition to the plasma membrane of a procaryotic cell all right that's it for this video I hope it was helpful thank you so much for watching and good luck with studying we invite you to subscribe to our Channel and share a link with your classmates and friends in nursing school and if you found value in this video be sure to hit that like button and let us snow which you found to be particularly helpful