CHM 112
GAGE
SPRING 2002
NAME ____________________________________
DATE_____________________________________
EXAM 5
1.
a.
Join the two amino acids below to form one of two possible dipepetides.
O
O
H2N
CH
C
(5)
OH
H2N
CH
C
OH
CH 2
CH 2
CH 2
C
O
OH
b.
Show by means of equations how glycine can act as a buffer.
(5)
O
H2N
CH
C
OH
H
c.
What is the tertiary structure of a protein and how is it maintained?
(5)
2.
At the end of this exam you will find a copy of the Krebs Cycle or the Tri-Acid Cycle.
Steps and compounds in this process have been numbered. Use these numbers to interpret and
respond to questions below where appropriate. When answering about a reaction, select the
clockwise direction unless otherwise indicated.
(16)
a.
What is the source of the pyruvate (1)?
________________________
b.
List the functional groups on molecule 4.
________________________
c.
What type of reaction is happening at 5?
________________________
d.
List any steps where the electron transport
chain will be engaged.
________________________
e.
After which step is the pyruvate totally oxidized?
________________________
f.
What type of reaction is occurring at 12?
________________________
g.
Which step is exothermic?
________________________
h.
What type of reaction is occurring at step 16?
________________________
i.
Explain why this metabolic pathway is shown with multidirectional arrows.
(4)
3. a.
Explain how an enzyme is able to increase the rate of a biochemical reaction.
(5)
b.
What does lactase dehydrogenase do?
(2)
c.
Sketch a graph of reaction rate as a function of substrate concentration and explain why
graph has the shape it does.
(4)
d.
Explain from a structural perspective why enzymes have a optimal temperature of
operation.
(4)