Question

5. What are the internal structures of the mitochondria and what parts of cellular respiration take place in each part? (inner/outer membranes, cristae, matrix, intermembrane space)

Answer 1

Internal structure of mitochondria is as below:

Protein synthesis mRNA Intermembrane space Outer membrane Mitochondrial Inner membrane envelope Matrix granule Matrix Pyruvate +acety! COA Fatty acid B-oxidation, Kreb's cycle Nucleic acid and protein synthesis Mitochondrial ribosomes Cristae Chromosome (DNA) Electron transfer Oxidative phosphorylation Steroid metabolism F. (stalk) F, (sphere) ATP synthase Intra crystal space - Crystal membrane Inter- membrane space Peripheral space Inner membrane Outer membrane Fig. 2.21. Diagrammatic representation of mitochondrion ultrastructure. A. Mitochondrial cross section showing various parts. B. Detailed structure of a crista.

cellular respiration taking place in each part of mitochondria is as given below:

1. Inner membrane: site of the electron transport chain, an important step in aerobic respiration.

2. Outer membrane: It is the gateway to the mitochondrion, just like the cell membrane is for the cell. It has porins to allow smaller proteins in and protein complexes to allow bigger proteins in. It works in concert with the inner membrane to allow these proteins into the matrix.

3. Cristae: electrons are passed through the electron transport chain, which pumps protons to power the production of energy molecules called ATP.

4. Matrix: site of Krebs Cycle reactions.

5. Intermembrane space: plays a pivotal role in the coordination of mitochondrial activities with other cellular processes. These activities include the exchange of proteins, lipids, or metal ions between the matrix and the cytosol, the regulated initiation of apoptotic cascades, signalling pathways that regulate respiration and metabolic functions, the prevention of reactive oxygen species produced by the respiratory chain, or the control of mitochondrial morphogenesis.