1. In the "DNA clock", some nucleotide changes cause amino acid substitutions in the encoded protein (nonsynonymous changes), and others do not (synonymous changes). In a comparison of rodent and human genes, rodents were found to accumulate synonymous changes 2.0 times faster than humans and nonsynonymous substitutions 1.3 times as fast. What factors could explain this difference? How do such data complicate the use of molecular clocks in absolute dating?
2. Imagine that Pangea were re-formed today. What might be some of the environmental effects, and how might these changes influence life on Earth?© BrainMass Inc. brainmass.com October 16, 2018, 8:14 pm ad1c9bdddf
1. Rodents are thought to have a "faster" molecular clocks because they have a higher metabolic rate, as well as a shorter generation time. With a faster metabolic rate, increased oxygen radicals (free radicals) are produced, and these are known to have mutagenic effects. In addition, the higher rates of DNA synthesis as well as nucleotide replacement in those animals with higher metabolic rates can help explain why the rate ...
Explain the processes of photosynthesis and cellular respiration.
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.
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. Propose a direction for future research and drug development for targeting mtDNA to combat the aging process.