Exam 2: FA Synthesis Flashcards
Primary tissue of FA synthesis
Liver
FA synthesis also occurs in the following tissues
Adipose tissue
Kidney
Mammary glands during lactation
Synthesis of FA occurs in
Cytosol
When isocitrate DH is inhibited by ATP, ____ accumulates
Citrate
When citrate accumulates, it is exported to the
Cytosol
High sugar forces glycolysis to make lots of ___ in the ___
ATP
Liver
Once citrate is exported to cytosol, ____ used it to produce acetyl CoA
Citrate lyase
After acetyl CoA is back in cytosol, ___ is created via _____
Malonyl CoA
Acetyl CoA carboxylase
FA synthesis keeps adding ___ to a growing FA chain
Malonyl CoAs
FA synthase is an ____ with multiple enzyme domains
Enzyme complex
One portion of FA synthase is this molecule
ACP
ACP stands for
Acyl Carrier protein
ACP is similar to
CoA
There is a terminal ___ group at the end of FAS
Thiol
Process of ACP of FAS grabbing acetyl’s
- ACP grabs acetyl
- ACP transfers acetyl to holding site
- ACP grabs malonyl
- Acetyl and Malonyl combine
- Ketone converted to alcohol
- Water removed
- Molecule reduced
FAS steps
Condensation
Reduction
Dehydration
Reduction
End product of FA synthesis
Palmitate (16:0)
FAS uses ___ to reduce
NADPH
NADPH is created in
Pentose Phosphate Pathway
FA are ____ molecules
Highly reduced
NADPH is created by this enzyme in the cytosol
Malic enzyme
Release of the FA is accomplished by
Palmitoyl Thioesterase
Part of FAS complex
Palmitate can be ____ and ___ by ____ and ___ (enzymes_
Elongated and desaturated
Elongases
Desaturases
Humans cannot create double bonds beyond the ____ carbon
9th-10th C
Conditions that stimulate FA synthesis
- High energy charge
- Lots of acetyl CoA
- Lots of NADH and FADH2
- Lots of citrate
- Lots of sugar
- Insulin
Degradation of FA to make ATP occurs in the
Mitochondria
Key enzymes in FA synthesis
Citrate lyase
Acetyl CoA carboxylase
FAS
In the cytosol, ____ releases acetyl CoA from citrate in preparation for FA synthesis
Citrate lyase
Eating lots of ___ stimulates fat synthesis
Sugar
GLUT2 Function
Transport glucose, galactose, and fructose out of intestine into liver
GLUT2 is ___ independent
Insulin
GLUT4 Function
Transport glucose into muscle and adipose tissue via facilitated diffusion
GLUT4 is stimulated by 2 things:
- Insulin
2. Low energy charge
About 90% of insulin-stimulated glucose uptake occurs in
Skeletal muscle
By adding a ___ to glucose, glucose concentration in muscle remains low and ___ keeps coming in
Phosphate
Glucose
When muscle energy charge is low, G6P runs through…
Glycolysis
Prep step
Krebs
When muscle glycogen is low, G6P is converted to
Glycogen
Exercise stimulates accumulation of ___ in cell membrane for 1-2 hours afterwards
GLUT4
Glucokinase is stimulated by
Insulin
Fructose
Glucokinase is ___ by its product
NOT inhibited
___ has a lesser affinity for glucose
Glucokinase
If glucose and does not need to go through glycolysis and glycogen is full, high energy charge will
Inhibit PFK
Inhibition of PFK causes ____ to accumulate
G6P
G6P inhibites
Hexokinase
Inhibition of hexokinase causes ___ to accumulate
Glucose
Glucose accumulation stops flow from ___ to ____
Blood into muscle
Rate limiting step in FA synthesis
Acetyl CoA carboxylase
Stimulation of ACC
Citrate
Insulin
Inhibition of ACC
Malonyl CoA
Palmitoyl CoA
Epinephrine
Glucagon
High calories increase synthesis of ____ via changes in transcription factor regulation
ACC
AMPK phosphorylates ACC, causing
Inactivation
Malonyl CoA inhibits
Carnitine acyl transferase I
Citrate inhibits
PFK1
___ is primary site of fructose disposal
Liver
___ and ___ are enzymes essential for fructose metabolism and are highly expressed in the ___
Fructokinase
Triokinase
Liver
___ and GLUT8 transport fructose into liver
GLUT2
____ has limited expression in muscle and adipose tissue
Triokinase
Small amounts of fructose cause the release of ___ from a regulatory protein
Glucokinase
Normally, F6P binds to GK regulatory protein and ____ is inhibited
Glucokinase
When F1P binds to regulatory protein, GK is set free and ___
Activated
Fructose skips the regulation of __
PFK
Fructose stimulates ___
Glucokinase
Fructose produces more ____ and ATP
Acetyl CoA
HSL is strongly inhibited by
Insulin
___ is elevated in type 2 diabetes
ATGL
___ is reduced in type 2 diabetes and heavily inhabited
HSL
HSL has 10 fold higher specific activity for ___ than ___
DAG
TAG
Imbalance of ____ breakdown in obese individuals
TAG/DAG
When the cell overexpresses more ATGL, more ___ is produced
DAG
Insulin inhibits HSL, which normally likes to break down ___
DAG
DAG accumulates and activates ____
PKC