BIOC3022 EXAM 4 COMPLETE
QUESTIONS WITH 100% VERIFIED
ANSWERS
\.how is triglyceride mobilized from adipocytes? - ANSWERS-lipolysis.
Uses lipases to release fatty acids from triglycerides. Lipolysis in adipose
tissue is stimulated by hormones that respond to fasting (glucagon) or
stress (epinephrine)
Hormone stimulation of GPCR activates adenylyl cyclase, increasing
cAMP and activating PKA which then phosphorylates lipases to activate.
These reactions release fatty acid from glycerol backbone
hormonal control of triacylglycerol lipase, then diacylglycerol lipase,
then monoacylglycerol lipase to liberate all 3 fatty acids from glycerol
backbone.
\.what are the steps to B-oxidation? - ANSWERS-B carbon undergoes
oxidation to release acetyl CoA.
,1. Dehydrogenation: of long chain fatty acid- creates C=C double bond.
Enzyme: Acyl CoA dehydrogenase. Electrons (H+) transferred to FAD and
released as FADH2.
2. Hydration: of double bond adds a hydroxyl group to B-carbon.
Enzyme: Enol CoA hydratase
3. Dehydrogenation: using NAD as an electron acceptor. Enzyme: 3-
hydroxyacyl dehydrogenase
4. Thiolysis: between C2 and C3. A new molecule of CoA breaks the
bond by nucleophilic attack on C3. Releases C1 and C2 as acetyl CoA.
Enzyme: B-ketothiolase
repeat to release 2nd acetyl CoA group
\.how are acyl-CoA molecules transferred into the mitochondria? -
ANSWERS-by having a carnitine group added to it. From CPT1. And then
CACT (translocase for carnitine) transfers it across the inner mito
membrane.
\.How is cycling between fatty acid synthesis and degradation avoided?
why do we want to avoid it? - ANSWERS-Quantities of malonyl CoA and
citrate regulate whether synthesis or oxidation is occurring
, Malonyl CoA is a regulatory molecule for Fatty acid synthesis and also
inhibits CPT1 allosterically.
Reduced malonyl CoA enables FFA oxidation and energy production
Citrate also regulates PFK and glycolysis rates- excess signals to
glycolysis to slow down and pushes C through PPP producing NADPH to
make FFA
\.how is glycerol used? - ANSWERS-is converted to DHAP and sent to
gluconeogenesis
\.what is the energy yield from FFA oxidation? - ANSWERS-7 FADH2
7NADH
8 acetyl CoA
129 ATP
\.What are the pathways of ketogenesis and ketolysis? Know enzymatic
pathways and how specific tissues utilize these molecules. - ANSWERS-
Ketolysis: breakdown of ketone molecules
Ketogenesis: the movement of carbon units from the liver to other
tissues during a starvation. B oxidation is restricted to the muscle and
QUESTIONS WITH 100% VERIFIED
ANSWERS
\.how is triglyceride mobilized from adipocytes? - ANSWERS-lipolysis.
Uses lipases to release fatty acids from triglycerides. Lipolysis in adipose
tissue is stimulated by hormones that respond to fasting (glucagon) or
stress (epinephrine)
Hormone stimulation of GPCR activates adenylyl cyclase, increasing
cAMP and activating PKA which then phosphorylates lipases to activate.
These reactions release fatty acid from glycerol backbone
hormonal control of triacylglycerol lipase, then diacylglycerol lipase,
then monoacylglycerol lipase to liberate all 3 fatty acids from glycerol
backbone.
\.what are the steps to B-oxidation? - ANSWERS-B carbon undergoes
oxidation to release acetyl CoA.
,1. Dehydrogenation: of long chain fatty acid- creates C=C double bond.
Enzyme: Acyl CoA dehydrogenase. Electrons (H+) transferred to FAD and
released as FADH2.
2. Hydration: of double bond adds a hydroxyl group to B-carbon.
Enzyme: Enol CoA hydratase
3. Dehydrogenation: using NAD as an electron acceptor. Enzyme: 3-
hydroxyacyl dehydrogenase
4. Thiolysis: between C2 and C3. A new molecule of CoA breaks the
bond by nucleophilic attack on C3. Releases C1 and C2 as acetyl CoA.
Enzyme: B-ketothiolase
repeat to release 2nd acetyl CoA group
\.how are acyl-CoA molecules transferred into the mitochondria? -
ANSWERS-by having a carnitine group added to it. From CPT1. And then
CACT (translocase for carnitine) transfers it across the inner mito
membrane.
\.How is cycling between fatty acid synthesis and degradation avoided?
why do we want to avoid it? - ANSWERS-Quantities of malonyl CoA and
citrate regulate whether synthesis or oxidation is occurring
, Malonyl CoA is a regulatory molecule for Fatty acid synthesis and also
inhibits CPT1 allosterically.
Reduced malonyl CoA enables FFA oxidation and energy production
Citrate also regulates PFK and glycolysis rates- excess signals to
glycolysis to slow down and pushes C through PPP producing NADPH to
make FFA
\.how is glycerol used? - ANSWERS-is converted to DHAP and sent to
gluconeogenesis
\.what is the energy yield from FFA oxidation? - ANSWERS-7 FADH2
7NADH
8 acetyl CoA
129 ATP
\.What are the pathways of ketogenesis and ketolysis? Know enzymatic
pathways and how specific tissues utilize these molecules. - ANSWERS-
Ketolysis: breakdown of ketone molecules
Ketogenesis: the movement of carbon units from the liver to other
tissues during a starvation. B oxidation is restricted to the muscle and
