# Tutor profile: Morgan B.

## Questions

### Subject: Biomedical Science

If a protein has a mutation in its primary structure, what does that mean? How does it affect the secondary and tertiary structure of the protein?

To answer this question, you must understand the basic structure of a protein and behavior of amino acids. The primary structure of proteins consists of the amino acid sequence, linked together by peptide bonds. If there is a mutation in the primary structure, that means that there has been a change in the amino acid sequence that was originally coded. Mutations in the primary sequence may have an effect on secondary and tertiary structure, but not always. The secondary structure is the formation of alpha-helices and beta-pleated sheets through hydrogen bonding in the peptide backbone, so a mutation in the primary structure does not usually affect the secondary structure. However, the tertiary structure is formed via R-group interactions, which are the interactions of R-groups on the amino acids in the primary structure. If an amino acid in the sequence has been changed, this may affect the way all R-groups in the protein are able to interact, and may prevent the protein structure from forming properly. However, if an amino acid has been changed to an amino acid with an R-group that behaves the same and is similar in size to the one originally coded for, there may not be a detrimental affect to the tertiary structure and the protein will be able to form its 3D shape properly.

### Subject: Basic Chemistry

A chemist has 100g of calcium chloride that they would like to use in an experiment they are running. How many moles of calcium chloride does the chemist have?

The first step to answering this question is finding the formula for calcium chloride. The two elements in the compound are calcium (Ca) and chlorine (Cl). Next, you must use the oxidation numbers to determine how many moles of each element there are in the compound. Ca has an oxidation number of 2+ and Cl has an oxidation number of 1-, so using the crossover method, you determine that the formula for calcium chloride is CaCl(2). Next, you need to determine the molar mass of CaCl(2). The molar mass of Ca is 40.08 g/mol and the molar mass of Cl is 35.45 g/mol. CaCl(2) has one mole of calcium and two moles of chlorine, so you would add the molar masses together as shown below to determine the molar mass of CaCl(2): 40.08 g/mol Ca x 1 mol = 40.08g Ca 35.45 g/mol Cl x 2 mol = 70.90g Cl 1 mol CaCl(2) = 40.08g + 70.90g = 110.98 g Now that we know the molar mass of CaCl(2), we can use the mass given in the question to find how many moles of CaCl(2) the chemist has. 100g CaCl(2) x 1 mol CaCl(2)/110.98g = 0.90 mol CaCl(2)

### Subject: Algebra

Anneke is interested in buying unique ornaments to decorate her Christmas tree. She saved $35.00 for this occasion. When she gets to the store, she notices that each decorative ornament costs $2.50. How many ornaments can Anneke buy?

Total saved = $35.00 Cost of 1 ornament = $2.50 Number of ornaments = x In order to find out how many ornaments Anneke can buy, we list the unknown number as "x" and create an algebraic expression to help us. $2.50 x (x) = $35.00 We know that if we multiply $2.50 by the number x, we can determine how much money buying ornaments costs. But, the word problem tells us that Anneke only has $35.00, so we set $2.50 x (x) equal to that amount. Next, we divide both sides by $2.50 to isolate x and find the number of ornaments Anneke can buy. By doing this, we find: x = 14 Therefore, Anneke can buy 14 ornaments with her $35.00.

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