AP Biology - Mitochondria FRQ Question

Question

1. Mitochondria can’t operate outside of a cell. What barriers prevent them from doing so and how might one try to circumvent those barriers?

Please provide as many bullet points as possible to answer this question :)

Answer 1

Mitochondria are unable to operate outside of a cell due to several fundamental reasons:

1. Dependence on Cellular Machinery: Mitochondria are reliant on the cellular environment, including access to nutrients, ions, enzymes, and cofactors, which are provided by the host cell. The intracellular milieu provides the necessary conditions for mitochondrial function and metabolism.
2. Interactions with Cellular Components: Mitochondria interact with other organelles and cellular components. For instance, they receive signals and communicate with the nucleus to coordinate cellular processes. Isolating them from this network of interactions would disrupt their function.
3. Genomic Integration: Mitochondria contain their own DNA (mitochondrial DNA or mtDNA) and genetic machinery. This DNA encodes some critical proteins essential for mitochondrial function. Separating mitochondria from the cell would prevent access to nuclear-encoded proteins needed for mitochondrial function.

To attempt to circumvent these barriers and study mitochondria outside the cell or in an isolated environment, researchers use techniques such as:

1. Mitochondrial Isolation: By carefully isolating mitochondria from cells while preserving their structure and function, researchers can study them in a controlled laboratory setting. Techniques involve using cell fractionation, differential centrifugation, and density gradient centrifugation to obtain purified mitochondrial fractions.
2. In Vitro Studies: Researchers can conduct in vitro experiments using isolated mitochondria to study specific mitochondrial processes, including oxidative phosphorylation, electron transport chain activity, ATP production, and mitochondrial membrane potential.
3. Artificial Liposomes or Nanoparticles: Creating artificial structures such as liposomes or nanoparticles that mimic aspects of the cellular environment can provide a medium for studying some aspects of mitochondrial function. These structures can encapsulate mitochondrial components and mimic certain features of the intracellular environment.
4. Reconstitution Studies: In some cases, researchers can reconstitute mitochondrial components or complexes in an artificial environment to study specific aspects of mitochondrial function. This involves isolating and reintroducing key proteins or complexes into an experimental setup.