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Biological Chemistry


The typical length of a DNA strand is 3.4cm. In order to fit into a cell, the DNA strand is supercoiled around proteins called histones. Histones are a family of five proteins thet are rich in the amino acids and lysine. How do histones stabilize the DNA strand? (look at the backbone of the DNA strand at the molecular level.)

Drawing Structures of Tetrapeptides

How to draw the structure of this tetrapeptide: Ala-Ser-Tyr-Thr What type of bonding between amino acid residues is most important in holding a protein and polypeptide in a specific secondary configuration?

Explanation for the Chemical Structure of Hydrocortisone

Can you please explain the chemical structure of cortisol and hydrocortisone? What is the difference on the structure? How many functional groups hydrocortisone has and what are they? What's in the chemical structure of hydrocortisone that makes it relieves the swelling and inflammation in the skin? Can you please explain

Threonine & Leucine

Which of the amino acids, threonine and leucine, would you expect to find on the inside of a globular protein and which would you expect on the outside, if either? Why?

Tripeptide Protein: Acidic, Basic, or Neutral?

Alanine has an R-group structure of CH3, cysteine has an R-group structure of HS-CH2, and aspartic acid has an R-group structure of HOOC-CH2 Write out the structural formula for this tripeptide, asp-ala-cys. Is the tripeptide basic, acidic, or neutral? How can you tell?

Current through proteins

A direct current was passed through a solution containing alanine, histidine, and aspartic acid at a pH of 6.0. One amino acid migrated to the cathode (+) and one migrated to the anode (-) and the other remained stationary. Match the behavior with correct amino acid. The isoelectric point of histidine is 10.0.

Proteins: Primary vs. Secondary Structures

Can there be a secondary structure without a primary structure? Why or why not? Can there be a primary structure without a secondary structure? Why or why not? What types of bonds are responsible for the secondary structure of a protein? How would the addition of a heavy metal affect the secondary structure of a protein?

Primary structure of glucagon

Glucagon His-ser-glu-gly-thr-phe-thr-ser-asp-tyr-ser-lys-tyr-leu-asp-ser-arg-arg-ala-gln-asp-phe-val-gln-trp-leu-met-asn-thr Which of the amino acids in the molecule would you expect to be on the inside of the protein? Why?

Are Albumins Polar or Nonpolar?

Blood is essentially an aqueous solution but it must transport a variety of non polar substances (hormones for example). Colloidal proteins, termed albumins, facillitate this transport. Must these albumins be polar or nonpolar?

Lidocaine and Bonding to Receptors

Draw abbreviated structural formulae of the products of the complete hydrolysis of lidocaine, and identity the functional groups from the first diagram attached. Lidocaine is thought to bond to receptors in its methylated form. Identify in writing the atoms or groups that could be involved in its bonding to a receptor via h

Chemistry Problem Set: Molecular Behaviour

Are the following questions true or false? a) A carboxylic acid favours the ion form (R-COO-) and its pH is higher than its pKa. b) In most membranes, the polar heads of the phospholipids align towards the middle of the membrane. c) All proteins contain either an alpha helix or beta sheets.

Understanding molecular behaviour

Are the following statements true or false? If false, explain why. a) In most globular proteins, the nonpolar amino acids tend to be concentrated at the surface of the protein. b) A small organic molecule required by an enzyme in order for the enzyme to be a functional catalyst is known as a vitamin. c) Lipids that are

Construct Standard Curve And Identify Unknown Sample's Value

Construct a standard curve from a data set and find the concentration of an unknown sample. The following data was obtained using spectrophotometry: Absorb.----------- ug/ml protein 0--------------------------0 0.22--------------------100 0.098-------------------50 0.086-------------------25 0.038------------------12.5