+
Cards In This Set
| Front | Back |
|
What is nitrogen fixation?
|
the formation of NH4+ from N2 gas
|
|
. Animals are totally dependent on plants and microorganisms for
nitrogen fixation and nitrate assimilation because animals:
|
lack the enzymes to reduce
N2 and NO3- to NH4+
|
|
Denitrifying bacteria are
capable of all EXCEPT:
|
oxidizing NH4+ to NO3-
|
|
Nitrogen fixation involves the enzyme ____ catalyzing the rxn: N2 + 10
____ + ___ e- à 2 NH4+ + H2
|
nitrogenase; H+; 8
|
|
The correct sequence for electron-transport in nitrate reductase is:
A.
NADH
B.
–SH
C.
FAD
D.
Cyt b557
E.MoCo
F.
NO3-
|
ABCDEF
|
|
All N2-fixing systems are nearly identical and have all of the
requirements except:
a. ATP
b. O2-free conditions
c. the enzyme nitrogenase
d. strong reductant
e. all are true
|
E. all are true
|
|
The involvement of ATP in
the nitrogenase complex is because ATP is needed to:
|
break the N2 triple bond
|
|
Control over nitrogenase
activity is accomplished by which of the following?
|
NH4+ prevents expression of
the genes that encode nitrogenase
|
|
N-acetylglutamate functions in ammonium incorporation into metabolic
intermediates as:
|
an allosteric activator for
carbamoyl-phosphate synthetase I (CPS-I)
|
|
What reaction does
glutamate dehydrogenase (GDH) catalyze?
|
the reductive amination of alpha-keto to yield glutamate
|
|
The rxn, glutamate + NAD(P) + H2O à NH4+ + alpha-keto + NAD(P)H
+ H+, is catalyzed by:
|
glutamate dehydrogenase
(GDH
|
|
Glutamine synthetase (GS) belongs to what class of enzymes?
|
ligase
|
|
The reaction, 2 NH4+ + alpha-keto + NADPH + ATP à glutamine + NADP+ + ADP +
Pi + H2O, is the combined result of what two enzymes?
|
glutamate dehydrogenase and
glutamine synthetase
|
|
Glutamate synthase (GOGAT) catalyzes the rxn ___ + ____ + ____ à 2 glutamate + NADP+
|
A. alpha-keto; NADPH; glutamine
|
|
Bacterial glutamine
synthetase (GS) monomers are inactive because they must be:
|
stacked for interface
active site development
|
