Biosynthesis of Fatty Acids & Eicosanoids Flashcards
(93 cards)
Which statetement is incorrect?
A. Fatty acids are synthesized by an extramitochondrial system, which is responsible for the complete synthesis of palmitate from acetyl-CoA in the cytosol.
B. In most mammals, glucose is the primary substrate for
lipogenesis, but in ruminants it is acetate, the main fuel molecule they obtain from the diet
C. inhibition of lipogenesis occurs in type 2 diabetes mellitus
D. variations in the activity of the lipogenesis affect the nature and extent of obesity.
C.
inhibition of lipogenesis occurs in type 1
(insulin-dependent) diabetes mellitus,
Which statement is incorrect?
A. Unsaturated fatty acids in phospholipids of the cell membrane are
important in maintaining membrane fluidity
B. high ratio
of saturated fatty acids to polyunsaturated fatty acids (S:P ratio) in the diet
is considered to be beneficial in preventing coronary heart disease
C. Animal tissues have limited capacity for desaturating fatty acids, and require certain dietary polyunsaturated fatty acids derived from plants.
D. essential fatty acids are used to form eicosanoic (C20) fatty acids, which
give rise to the eicosanoids prostaglandins, thromboxanes, leukotrienes,
and lipoxins
B
high ratio
of polyunsaturated fatty acids to saturated fatty acids (P:S ratio) in the diet
is considered to be beneficial in preventing coronary heart disease
mediate inflammation, pain, induce sleep,
and also regulate blood coagulation and reproduction.
Prostaglandins
act
by inhibiting prostaglandin synthesis
Nonsteroidal
anti-inflammatory drugs (NSAIDs)
have muscle contractant and chemotactic properties and are important in allergic
reactions and inflammation.
Leukotrienes
Which is true of lipogenesis?
A. Synthesis of fatty acids (lipogenesis) occurs in the cytosol
B. Lipogenesis cofactor includes NADPH, ATP, Mn2+, biotin, and HCO3
C. Acetyl-
CoA is the immediate substrate
D. free palmitate is the end product.
E. All of the above
F. None of the above
E. All of the above
source of CO2 and is required in the initial reaction for the
carboxylation of acetyl-CoA to malonyl-CoA
Bicarbonate
what enzyme is responsible for conversion of acetyl-CoA to malonyl-CoA
acetyl-CoA carboxylase
Acetyl-CoA carboxylase has a requirement for what vitamin
B vitamin biotin
Enzyme that involves in carboxylation of biotin involving ATP
Biotin carboxylase
covalently linked to the BCP
Biotin
a homodimer of
two polypeptide chains containing six enzyme
activities and the acyl carrier protein
Fatty Acid Synthase Complex
ACP contains with vitamin as cofactor?
pantothenic acid
Which one is the correct sequence of enzyme domains of fatty acid synthase
A. n-Ketoacyl synthase-Maolnyl/acetyl transacylase-ACP-enoyl reductase-dehydratase-thioesterase-c
B. n-Ketoacyl synthase-Maolnyl/acetyl transacylase-dehydratase-enoyl reductase-ketoacyl reductase-ACP-thioesterase-c
C. n-thioeterase-ACP-enoyl reductase-dehydratase-Maolnyl/acetyl transacylase-
keto acyl synthase-n
D. None of the above
B. n-Ketoacyl synthase-Maolnyl/acetyl transacylase-dehydratase-enoyl reductase-ketoacyl reductase-ACP-thioesterase-c
This enzyme catalyzes
reactions to form acetyl (acyl)-malonyl enzyme.
malonyl acetyl
transacylase
a priming molecule of acetyl-CoA combines with a? (REACTION 1A)
cysteine —SH group
combines
with the adjacent —SH on the 4′-phosphopantetheine of ACP of the other
monomer (REACTION 1 B)
malonyl-CoA
WHAT ENZYME catalyzeS REACTIONS 1A AND 1 B by , to form acetyl (acyl)-malonyl enzyme
malonyl acetyl transacylase
The acetyl group attacks the methylene group of the malonyl residue, catalyzed by _____________ and liberates CO2, forming 3-ketoacyl enzyme
(acetoacetyl enzyme) (reaction 2), freeing the cysteine —SH group.
3- ketoacyl synthase
The 3-ketoacyl group is reduced, dehydrated, and reduced again (reactions 3-5) to form the corresponding ______________________ (product of reaction 5).
saturated acyl enzyme
A new malonyl-CoA molecule combines with the ___________, displacing the saturated acyl residue onto the free cysteine —SH group.
—SH of 4′- phosphopantetheine
The sequence of reactions is repeated six more times
until a saturated 16-carbon acyl radical (palmitoyl) has been assembled. Then it is liberated from the enzyme complex by the activity of the _________
sixth enzyme
in the complex, thioesterase (deacylase).
Which of the statement is incorrect?
A. The acetyl-CoA used as a primer forms carbon atoms 15 and 16 of palmitate.
B. The addition of all the subsequent C2 units is via malonyl-CoA.
C. Propionyl-CoA instead of acetyl-CoA is used as the primer for the synthesis of long-chain fatty acids with an odd number of carbon atoms
D. All of the above
E. None of the above
E. None of the above
involved as a donor of reducing equivalents in the reduction of the 3-ketoacyl and the 2,3-unsaturated acyl derivatives
NADPH