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Olivia C.
PhD Student, research in biophysics
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Biomedical Science
TutorMe
Question:

Many diseases are caused by a single amino acid mutation. Why is a small shift in DNA sequence, such as a nucleic acid insertion or deletion, detrimental in some cases?

Olivia C.
Answer:

Proteins in the human body are encoded in the DNA, with every 3 DNA bases representing one amino acid. The DNA sequence is very specific, and if one DNA base is missing or changed, this can shift the pattern of 3 bases down the line, to completely skip an amino acid or change it to something else. For example, if glycine, a very flexible amino acid, is changed to a proline, a rigid and kinked amino acid, the entire protein will likely change shape. Changing the shape or chemistry of a protein will likely alter its function, or it may promote amyloid formation. Amyloids are aggregates of misfolded proteins that cannot be destroyed by normal protein degradation, which promotes diseases like Alzheimer's or Diabetes mellitus type 2. In conclusion, every amino acid plays a role in protein structure and function. If the sequence is altered just a little bit, it could very well cause disease.

Basic Chemistry
TutorMe
Question:

What is the chemical explanation to why oil and water do not mix? What can you add to a solution of water and oil to make them mix?

Olivia C.
Answer:

There a few chemical explanations as to why oil and water do not mix. First, they have different densities. Oil is less dense than water, or in other words, its molecules are not as compact. Second, the interactions between water molecules are strong when there are many of them. Water molecules are more attracted to water molecules, rather than to oil molecules. Because of the hydrophobic effect, water molecules will orient themselves in the the pattern that requires the least amount of energy, which forces the oil molecules to interact with each other, probably in a large droplet. Adding detergent to a mixture of oil and water will help them mix. Detergent molecules are attracted to both oil and water, so addition of detergent plus a little bit of shaking will make an emulsion of oil and water.

Biology
TutorMe
Question:

What is convergent evolution? Give a definition, an example, and explanation of the importance of this concept.

Olivia C.
Answer:

Convergent evolution is the process where organisms develop similar traits but are not closely related to each other. An example of convergent evolution is wings on bats (mammals) and birds. Although they did not evolve at the same time, their wings serve the same purpose now. This concept is important to remember in light evolution, because although many organisms have similar features such as wings, it does not mean they are closely related, or that the features came about at the same time in evolution.

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