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CH 28: Fatty acid synthesis

Terms in this set (28)

CLICKER: what is the name of the 16 carbon saturated fatty acid?
Palmitic acid
What are the three stages of fatty acid synthesis
1. transfer of Acetyl CoA out of the mitochondria into the cytoplasm
2. Activation of acetyl CoA in the cytoplasm to form malonyl CoA
3. Repetitive addition and reduction of 2 carbon units to synthesize C16 fatty acid
In stage 3 of fatty acid synthesis, where does synthesis of C16 fatty acid occur
on an acyl carrier protein, a molecular scaffold
In stage 1 of fatty acid synthesis, citrate is transported into the cytoplasm and cleaved into
oxaloacetate and acetyl CoA
List the sequence of events of the citric acid cycle
1. C-C bond formation between acetate (2C) and oxaloacetate (4C) to make citrate (6C)
2. isomerization via dehydration/rehydration
3/4. oxidative decarboxylation to give 2 NADH
5. Substrate level phosphorylation to give GTP
6. dehydration gives FADH2
7. hydration
8. dehydration gives NADH
___ carries acetyl groups from mitochondria to the cytoplasm
citrate
Citrate that is made in the mitochondria is transported to the cytoplasm and cleaved by ___ to generate acetyl CoA for fatty acid synthesis
ATP-citrate lyase
In stage 1 of fatty acid synthesis, what are the conditions that promote fatty acid synthesis
1) High ATP levels in the matrix allosterically inhibits isocitrate dehydrogenase
2) CAC stops, isocitrate accumulated
3)inhibition of isocitrate dehydrogenase leads to accumulation of citrate in the matrix of mitochondria
4) citrate can be moved into cytoplasm
5) the accumulation of citrate will promote Fatty Acid Synthesis
___ is the indicator of high energy in the cell
citrate
citrate acts as a ___ effector for the first enzyme of
positive, fatty acid biosynthesis
A high level of citrate will inhibit __ and divert the carbohydrate that has been fragmented from combustion to the formation of
carbohydrate fragmentation, lipids
In stage 2 of fatty acid synthesis, Malonyl-CoA is formed from
acetyl-CoA and bicarbonate
What is the committed step in fatty acid synthesis
formation of malonyl CoA
in stage 3 of fatty acid synthesis, the synthesis of fatty acids is catalyzed by
fatty acid synthase (FAS)
FAS catalyzes a repeating 4 step sequence that elongates the fatty acid chain by __ carbons in each step
2
NADPH is used as an ____ in stage 3 of fatty acid synthesis
electron donor
What is the overall goal of fatty acid synthesis
To attach acetate unit (2 carbon) from malonyl CoA to a growing chain and reduce it
The reaction of fatty acid synthesis involves cycles of 4 enzyme-catalyzed steps. What are they ?
1. Condensation : of the growing chain with activated acetate
2. Reduction : of carbonyl to hydroxyl
3. Dehydration : of alcohol to trans-alkene
4. Reduction : of alkene to alkane
The growing chain of fatty acids are initially attached to the enzyme via
thirster linkage
___ acetyl CoA are carboxylated to make __ malonyl CoA using __
7,7, ATP
There are ___ cycles of condensation, reduction, dehydration, and reduction

These cycles use ___ to reduce ___ and a trans-double bond
7

NADPH, B-Keto
Where does fatty acid synthesis occur?
cytoplasm
The source of carbon atoms for growing fatty acid chain is
acetyl CoA
Fatty acid synthesis is catalyzed by a single enzyme called __. It contains 7 different catalytic sites in one polypeptide chain.
fatty acid synthase
What is the intermediate of fatty acid synthesis linked to
acyl carrier protein (ACP)
fatty acid synthase is driven by the release of CO2 in a decarboxylation step, what is used in the carboxylation step
ATP
fatty acid synthesis requires a reducing power obtained from __ to go through reduction steps
NADPH
fatty acid synthesis leads to the production of a single product and no intermediates. What is the final product
16 carbon saturated fatty acid.
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