Yamxx
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This is a BMAT past paper question I need help with:

21. Mitochondria are the site of aerobic respiration in animal cells. A theory of the evolution of animal cells states that these mitochondria may once have been aerobic bacteria that were taken into the cytoplasm of a cell in an early ancestor of the animals, allowing the cells to gain the ability to respire using oxygen.
Assuming this theory is correct, which of the following statements are true of these aerobic bacteria and human white blood cells?

1 The structure of their DNA is a double helix.
2 They would both possess a cell wall.
3 They would both possess a nucleus.
4 They would both possess a cell membrane.

The answer is 1 and 4 only

Why is that?

Thank you!
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username2199397
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Bassically they are saying that these Aerobic bacteria are animal cells. (Mitochondria were considered as individual single-membraned bacteria cells that lived inside another cell hence why mitochondria have a double cell membrane one from mitochondria (bacteria) and the other (outer) from the cell it used to live inside of. So what's the similarities between animal cells and white blood cells eg. Neutrophil? They both don't contain cell walls and only white blood cell contains a nucleus (multilobbed), mitochondrion only contain extra chromosomal dna (mDNA) not a nucleus. Do its 1 and 4
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Yamxx
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(Original post by shohaib712)
Bassically they are saying that these Aerobic bacteria are animal cells. (Mitochondria were considered as individual single-membraned bacteria cells that lived inside another cell hence why mitochondria have a double cell membrane one from mitochondria (bacteria) and the other (outer) from the cell it used to live inside of. So what's the similarities between animal cells and white blood cells eg. Neutrophil? They both don't contain cell walls and only white blood cell contains a nucleus (multilobbed), mitochondrion only contain extra chromosomal dna (mDNA) not a nucleus. Do its 1 and 4
Thank you!
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OxFossil
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(Original post by Yamxx)
Thank you!
Although the answer remains the same, shohaib712's answer is not quite accurate. Mitochondria arose from bacterial (prokaryote) endosymbionts, rather than being animal (eukaryotes) endosymbionts. They have retained many of the features of this ancestral bacterial origin. The ancestral pro-mitochondrion was probably something like Rickettsia, which has a DNA genome. That's why point 1 is correct. However, unlike eukaryotes (including humans), bacteria do not possess a nucleus. That accounts for point 3.

Neither animals nor bacteria have a plant-like cell wall, but cell membranes or capsules (the outer wall of the mitochondrion is probably derived from the original bacterium, rather than being the membrane of the original host.) That's why point 4 is correct and point 2 is incorrect.
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Yamxx
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(Original post by OxFossil)
Although the answer remains the same, shohaib712's answer is not quite accurate. Mitochondria arose from bacterial (prokaryote) endosymbionts, rather than being animal (eukaryotes) endosymbionts. They have retained many of the features of this ancestral bacterial origin. The ancestral pro-mitochondrion was probably something like Rickettsia, which has a DNA genome. That's why point 1 is correct. However, unlike eukaryotes (including humans), bacteria do not possess a nucleus. That accounts for point 3.

Neither animals nor bacteria have a plant-like cell wall, but cell membranes or capsules (the outer wall of the mitochondrion is probably derived from the original bacterium, rather than being the membrane of the original host.) That's why point 4 is correct and point 2 is incorrect.
Thank you I can now fully understand the answer!
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