Exam #2

Question 1

A pore that simultaneously transports two different molecules in the same direction is…

Answer 1

symport

Question 2

The _________ model describes the cell membrane as an assortment of integral proteins suspended freely in a lipid bilayer.

Answer 2

Fluid Mosaic

Question 3

While the binding of O2 to myoglobin as a function of pO2 is described by a simple _____________, the binding to hemoglobin is described by a more complex __________ curve.

Answer 3

Hyperbolic ; Sigmoidal

Question 4

Bacteria cell walls are composed of _________.

Answer 4

Peptidoglycans

Question 5

Which of the following increases the affinity of hemoglobin for O2?

Answer 5

an increase in pH

Question 6

When two carbohydrates are epimers

Answer 6

They differ only in the configuration around one carbon atom.

Question 7

The basic structure of a proteoglycan consists of a core protein and a :

Answer 7

glycosaminoglycan

Question 8

Carbohydrate metabolic enzymes bind D-glucose specifically. D-glucose has an estimated caloric value of 1kcal per 4 grams of carbohydrate. Based on the methods used to convert the energy of D-glucose into a useable form, what would you estimate the caloric value of L-glucose to be using the same method?

Answer 8

0 kcal per 4 grams; this is because L- enantiomers can’t be readily used.

Question 9

A good transition-state analog:

Answer 9

binds to the enzyme more tightly than the substrate.

Question 10

Both water and glucose share an -OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is _________.

Answer 10

the larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis.

Question 11

Allosteric enzymes…

Answer 11

usually have more than one polypeptide chain

Question 12

Enzyme catalysts

Answer 12

Increase the reaction rate for a given reaction by a thousand-fold or more.

Question 13

One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under conditions of zinc deficiency, when the enzyme may lack zinc, it would be referred to as the :

Answer 13

Apoenzyme

Question 14

Which vitamins are fat-soluble?

Answer 14

A, D, E K

Question 15

Which vitamins are not fat-soluble?

Answer 15

C