Question 1

A chiral molecule called L-malic acid has the following physical properties: it has a melting point of $102^	ext{o}C$, rotates polarized light $+27^	ext{o}$ to the left, and has two pKa values, $pK_a = 3.4$ and $pK_a = 5.2$. What are the physical properties of its enantiomer D-malic acid?

Accepted Answer

Melting point $102^	ext{o}C$, rotates polarized light $-27^	ext{o}$ to the right, pKa values $3.4$ and $5.2$

Question 2

Which of the following amino acids contains an aromatic side chain?

Accepted Answer

phenylalanine

Question 3

What is the relationship between the two molecules shown in the Fischer projection below?

$\begin{array}{cccc}
A & & B \
| & & | \
D & & C \
\end{array}$

Accepted Answer

They are enantiomers

Question 4

Which of the following is a non-essential amino acid used to make proteins?

Accepted Answer

$\mathrm{HO{-}CH_2{-}CH(NH_2){-}COOH}$ (serine)

Question 5

Which pair of amino acids can have hydrophobic interactions?

Accepted Answer

glycine and alanine

Question 6

Enzymes function as catalysts by:

Accepted Answer

lowering the activation energy ($E_a$)

Question 7

The enzyme Chymotrypsin cuts the polypeptide backbone on the carboxy side of aromatic amino acids. If the following polypeptide is cut:
Asp-Tyr-Phe-Glu-Asn-Cys-Pro-Lys-Gly
Where will the first cut occur?

Accepted Answer

Between Tyr and Phe

Question 8

Which of the following does NOT increase the rate of a reaction?

Accepted Answer

Increasing the products

Question 9

A Fischer projection of D-glucose is shown. Which number carbon is responsible for giving it the 'D-' designation?

$\begin{array}{c}
HOCH_2 \
| \
C_1 \
| \
C_2 \
| \
C_3 \
| \
C_4 \
| \
C_5 \
| \
CH_2OH 
\end{array}$

Accepted Answer

5

Question 10

What makes a sugar a 'reducing' sugar and what are some examples of reducing and non-reducing sugars?

Accepted Answer

A sugar is reducing if it has a free anomeric carbon; examples: glucose (reducing), sucrose (non-reducing)

Question 11

What is the glycosidic bond linkage in the molecule shown below?

$\mathrm{	ext{Glucose}-\alpha(1ightarrow4)-	ext{Glucose}}$

Accepted Answer

$\alpha$-1,4 glycosidic

Question 12

The conversion of cyclic D-glucose between the alpha form and the beta form is called:

Accepted Answer

mutarotation

Question 13

Which of the following is the correct description of the relationship between the two molecules shown below?

$\begin{array}{c}
	ext{Molecule 1:} \
	ext{D-glucose} \
	ext{Molecule 2:} \
	ext{L-glucose} 
\end{array}$

Accepted Answer

They are enantiomers

Question 14

Reduction of glucose with $\mathrm{H_2}/\mathrm{Pt}$ forms which product?

Accepted Answer

sorbitol (an alcohol at the C1 carbon)

Question 15

An enzyme that catalyzes the conversion of a cis double bond to a trans double bond is classified as a(n):

Accepted Answer

isomerase

Question 16

The theory that suggests that an enzyme is a flexible molecule whose shape is altered by the reaction conditions or substrate binding is the ______ model.

Accepted Answer

induced-fit

Question 17

Which of the following is NOT a type of non-substrate level control for enzymes?

Accepted Answer

zymogen control

Question 18

Classify D-glucose according to the location of its carbonyl group (aldo/keto) and the number of carbon atoms it has.

Accepted Answer

An aldose with 6 carbons

Question 19

Which of the following is required by some protein enzymes to become enzymes that function properly (called an 'ideal apoenzyme')?

Accepted Answer

coenzyme

Question 20

Which of the following statements best describes the difference between cellulose and starch?

Accepted Answer

Cellulose has $\beta$-1,4 glycosidic bonds, while starch has $\alpha$-1,4 and $\alpha$-1,6 glycosidic bonds

GOB Chemistry Study Guide: Amino Acids, Enzymes, Carbohydrates, and Polysaccharides

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