MCAT Biology : Functional Groups and Properties
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Example Question #21 : Functional Groups And Properties
Which of the following compounds will be the most reactive with an alcohol to form an ester product?
Acid chloride
Amide
Acid anhydride
Carboxylic acid
Acid chloride
All of the options, except for the carboxylic acid itself, are derivatives of a carboxylic acid. These derivatives differ in their reactivity when creating new compounds. Acid chlorides are the most reactive compounds, and amides are the least reactive out of these option. Acid chlorides and acid anhydrides frequently participate in reactions, while amides are less likely to react.
Example Question #22 : Functional Groups And Properties
What is the least reactive acid derivative?
Ester
Acid chloride
Carboxylic acid
Amide
Amide
The reactivity of acid derivatives is largely dependent on the leaving group. If the leaving group is a strong base it is considered a poor leaving group, which makes it less reactive. Amides have a leaving group that is a very strong base, compared to other options. As a result, amides are very stable compounds and are the least reactive out of the options.
Example Question #91 : Molecular Properties
Understanding the function of the sodium-potassium pump, which of the following residues might possibly line the channel?
Lysine
Isoleucine
Aspartic acid
Oleic acid
Aspartic acid
Aspartic acid is the only viable answer. Its R-group contains a second carboxylic acid that is deprotonated in most physiological conditions. The negatively charged aspartate will interact favorably with the positively charged cations moving through the pump. Lysine is a basic amino acid that contains an amine group at the terminal end of its R-group. Isoleucine is an aliphatic and hydrophobic amino acid. Oleic acid is an example of a fatty acid, which can carry a negative charge in some conditions, but it is not an amino acid and thus cannot be incorporated into a protein.
Example Question #24 : Functional Groups And Properties
Carbonic anhydrase is a very important enzyme that is utilized by the body. The enzyme catalyzes the following reaction:
A class of drugs that inhibits this enzyme is carbonic anhydrase inhibitors (eg. acetazolamide, brinzolamide, dorzolamide). These drugs are commonly prescribed in patients with glaucoma, hypertension, heart failure, high altitude sickness and for the treatment of basic drugs overdose.
In patients with hypertension, carbonic anhydrase inhibitors will prevent the reabsorption of sodium chloride 
When mountain climbing, the atmospheric pressure is lowered as the altitude increases. As a result of less oxygen into the lungs, ventilation increases. From the equation above, hyperventilation will result in more 
Carbonic anhydrase inhibitors are useful in patients with a drug overdose that is acidic. The lumen of the collecting tubule is nonpolar. Due to the lumen's characteristic, molecules that are also nonpolar and uncharged are able to cross the membrane and re-enter the circulatory system. Since carbonic anhydrase inhibitors alkalize the urine, acidic molecules stay in a charged state.
James is designing a protein that is able to reabsorb back into the bloodstream in the presence of a carbonic anhydrase inhibitor. For this protein to be reabsorbed, which of the following animo acid(s) should the protein be abundant in?
I. Glu
II. Asn
III. Gln
II and III
I only
I and III
III only
II only
II and III
A carbonic anhydrase inhibitor will alkalinize the urine. Amino acids with an acidic side chain will lose their hydrogen and become charged in a basic condition. Amino acids that are basic will stay in an uncharged state and will be able to cross the lumen membrane of the collecting tubule. Of the answer choices, only asparagine (Asn) and glutamine (Gln) will stay in a neutral state due to the base property of the side chain. Glutamic acid (Glu) will lose its proton in the basic environment and will become charged.
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