Lecture 5: SBT 2103: Cellular Basis of Life:
Similarities between mitochondria and chloroplasts:
Mitochondria and chloroplast both have:
A double membrane surrounding the organelles.
Purportedly prokaryotic origins according to the endosymbiotic theory which suggests that
mitochondria and chloroplast were once prokaryotic bacteria engulfed by endocytosis in
early eukaryotes.
Their own circular DNA which codes for certain enzymes required for the chemical
reactions that take place in these organelles.
Their own 70S ribosomes made up of 50S and 30S subunits to translate proteins
The enzyme ATP synthase which utilizes the energy released from the movement of
protons across it (proton-motive force) to phosphorylate ADP to ATP. (Thus, another
similarity would be that they both produce ATP)
Electron transport chains, which are embedded in the inner mitochondrial membrane and
thylakoid membrane in mitochondria and chloroplasts respectively.
Both organelles have chemical cycles in which the initial acceptor is regenerated at the end
of the cycle. In mitochondria, the Krebs cycle occurs after which oxaloacetate is
regenerated at the end of the reaction. In chloroplasts, the Calvin cycle occurs in which
ribulose bisphosphate (RuBP) is regenerated at the end of the reaction.
Differences between mitochondria and chloroplasts:
Mitochondria are involved in cellular respiration whereas chloroplasts are involved in
photosynthesis. Thus, the overall chemical reactions for the processes occurring in them
are different and reversed.
- Respiration: C6H12O6+6O2 ---> 6CO2+6H2O+ATP
- Photosynthesis: 6CO2+6H2O --->C6H12O6+6O2
Mitochondria are found in all animal and plant cells. Chloroplasts, however, are found in
only specific types of plant cells, such as the palisade mesophyll and spongy mesophyll
cells of leaves. These cells are the ones involved in carrying out photosynthesis. Other
types of plant cells, such as root cells do not contain chloroplasts.
Chloroplasts contain pigments such as chlorophyll a, chlorophyll b and carotenoids.
Mitochondria do not contain any such pigments.
The types of electron acceptors present in mitochondria and chloroplast vary. While
mitochondria contain NAD and FAD, chloroplasts contain NADP.
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Similarities between mitochondria and chloroplasts:
Mitochondria and chloroplast both have:
A double membrane surrounding the organelles.
Purportedly prokaryotic origins according to the endosymbiotic theory which suggests that
mitochondria and chloroplast were once prokaryotic bacteria engulfed by endocytosis in
early eukaryotes.
Their own circular DNA which codes for certain enzymes required for the chemical
reactions that take place in these organelles.
Their own 70S ribosomes made up of 50S and 30S subunits to translate proteins
The enzyme ATP synthase which utilizes the energy released from the movement of
protons across it (proton-motive force) to phosphorylate ADP to ATP. (Thus, another
similarity would be that they both produce ATP)
Electron transport chains, which are embedded in the inner mitochondrial membrane and
thylakoid membrane in mitochondria and chloroplasts respectively.
Both organelles have chemical cycles in which the initial acceptor is regenerated at the end
of the cycle. In mitochondria, the Krebs cycle occurs after which oxaloacetate is
regenerated at the end of the reaction. In chloroplasts, the Calvin cycle occurs in which
ribulose bisphosphate (RuBP) is regenerated at the end of the reaction.
Differences between mitochondria and chloroplasts:
Mitochondria are involved in cellular respiration whereas chloroplasts are involved in
photosynthesis. Thus, the overall chemical reactions for the processes occurring in them
are different and reversed.
- Respiration: C6H12O6+6O2 ---> 6CO2+6H2O+ATP
- Photosynthesis: 6CO2+6H2O --->C6H12O6+6O2
Mitochondria are found in all animal and plant cells. Chloroplasts, however, are found in
only specific types of plant cells, such as the palisade mesophyll and spongy mesophyll
cells of leaves. These cells are the ones involved in carrying out photosynthesis. Other
types of plant cells, such as root cells do not contain chloroplasts.
Chloroplasts contain pigments such as chlorophyll a, chlorophyll b and carotenoids.
Mitochondria do not contain any such pigments.
The types of electron acceptors present in mitochondria and chloroplast vary. While
mitochondria contain NAD and FAD, chloroplasts contain NADP.
1
