Cellular Respiration and photosynthesis are paired processes. Photosynthesis converts light energy into organic molecules (i.e. carbohydrates). These molecules are used as fuel sources in organisms that employ cellular respiration for production of ATP and carbon dioxide.

Although it appears that Photosynthesis has preceded Cellular Respiration by billions of years, the processes share many structural features.

1. Create a table comparing and contrasting the two processes. Include in your comparison variables such as organism type, energy source, cellular location, substrates/reactants/products, full and balanced chemical reaction, carrier molecules, and any other parameter you find relevant.

Photosynthesis Respiration
organisms green plants, some bacteria all living organisms
description light is converted into energy used the chemical bonds of molecules (glucose) are broken for cellular processes, in the down, releasing energy used for cellular form of ATP, NADPH, processes, in the form of ATP
and eventually, glucose
energy source water, light, carbon dioxide glucose, oxygen
products carbohydrates, oxygen water, carbon dioxide
basic equation 6CO2+12H2O+energy=C6H12O6+6O2+6H2O C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
cellular location chloroplasts mitochondria (in eukaryotes), cell membrane (in prokaryotes)

2. Apart from its essential role in cellular respiration, the mitochondrion is thought to be implicated in a variety of disease states as well as the process of aging. The mitochondrion contains its own circular DNA molecule(s) (termed mtDNA) which largely encodes for proteins localized to the mitochondrion itself. Please provide a hypothesis and suggest an experiment to test the relationship between mtDNA and human aging.

Mutations in mtDNA genes have been linked to several diseases and to the aging process. Many of the symptoms of mtDNA-linked diseases are seen in elderly people (Alzheimer's disease, diabetes, muscle weakness, vision loss, etc.). It is hypothesized that mitochondria are involved in the aging process because a byproduct of cellular respiration is oxygen free radicals, which can attack the proteins used in cellular respiration and the mtDNA.

One hypothesis that could be tested is that certain mutations in mtDNA cause aging-related symptoms. The experiment could be:
1. Screen the mtDNA of young people and old people and see if there are any mutations that occur more often in the old people.
2. Pick one of the mutations to study. Then you could do one or both of the following:
3a. Study the DNA of a large number of people and take their family histories. You would predict that people who have the mutation would have family members who died at a younger age than would be expected, or that they would have family members who had more neurodegenerative disorders and other aging-related diseases than would be expected.
3b. Create a strain of transgenic mice with the mutation. You would predict that the mice with the mutation would age faster and/or die younger than the normal mice.

Propose a direction for future research and drug development for targeting mtDNA to combat the aging process.

Coenzyme Q10 is involved in cellular respiration and is thought to protect cells from damage caused by free radicals. CoQ10 and other antioxidants (such as vitamins A, C, E and selenium) could be used in supplement or topical forms to treat cellular damage caused by free radicals (I think I've seen commercials for lotion with CoQ10 in it).

Alternatively, if the disease you want to treat is related to a mutation in a mtDNA gene, in the future, it could be treated by introducing normal copies of the gene into the cell using gene therapy.