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WorksheetsBiochem Exam 3: Ketone Body Metabolism
Total questions: 92
Worksheet time: 49mins
Ketone bodies can move through the blood.
True
False
ketone Bodies are the ideal fuel source for the brain.
How long after a meal is it considered the "fasting state"?
3-8 hours
4-24 hours
1-2 hours
Postprandial means
before a meal
after a meal
during a meal
fasting state
During the fasting state, what is released from adipose tissues?
nitric oxide
glucose
fatty acids stored as TAGs
What enzyme cleaves 3 FAs from TAGs?
pancreatic enzymes
HS lipase
debranching enzyme
What transports free Fatty acids through the blood?
Albumin
chylomicrons
Where are FA oxidized to generate Acetyl-CoA, NADH and FADH2?
muscle
adipose tissue
kidney
liver
What is generated from B-oxidation of fatty acids in the liver?
NADH
NADPH
acetyl-CoA
FADH2
What is an alternate fuel source during fasting?
ketones
glulcose
What is the starting material used to produce ketone bodies?
citrate
glucose
Acetyl-CoA
NADH
Ketones bodies require carriers to be transported through the blood.
True
False
Acetoacetate and B-hydroxybutyrate are
ketones
esters
amino acids
basic
Acetoacetate and B-hydroxybutyrate are
organic bases
organic acids
Palmitic acid (16:0) is soluble in blood.
True
False
Which organ is the primary organ for ketone body synthasis?
Kidney
Liver
Pancreas
The liver can also use ketones and break them down for energy.
True
False
What causes ketogenesis?
fed state
fasting/starving
eating carbohydrates
restricting carb intake
What is considered starvation conditions?
4-24 hours
>24 hours
<24 hours
Ketogenesis leads to intensive mobilization of FA by the adipose tissue (lipolysis)
True
False
Ketone bodies are used as replacement glucose in which tissues?
cardiac muscle
skeletal muscle
kidneys
liver
When we have high levels of acetyl-CoA from B-oxidation of FA....
ketogenesis
glycolysis
During fasting conditions, Oxalaoacetate is diverted to
glycolysis
citric acid cycle
gluconeogenesis
What are the 2 ketone bodies?
acetoacetate
acetyl CoA
glucose
B-hydroxybutyrate
Ketone bodies are used in
liver
extrahepatic tissues
If acetyl-CoA is NOT feeding into the citric acid cycle, oxaloacetate will start feeding into gluconeogenesis to make glucose for the brain.
True
False
In fasting state, increased B-oxidation does what to acetyl Co-A levels?
increases
decreases
Acetyl CoA INHIBITS
pyruvate dehydrogenase complex
pyruvate carboxylase
A buildup of acetyl CoA does what to the TCA?
Inhibits
Activates
Increases Acetyl CoA ACTIVATES...
pyrvate dehydrogenase complex
Pyruvate carboxylase
CAC
increase pyruvate carboxylase --> more oxaloacetate --> promotes gluconeogenesis --> releases glucose for the brain
True
False
What must be present for Acetyl CoA to enter the CAC?
sufficient oxaloacetate
ketone bodies
lactate
During fasting state, acetyl CoA enters
CAC
ketogenesis
Where does beta oxidation occur?
cytoplasm
Smooth ER
mitochondrial matrix
B-oxidation GENERATES acetyl CoA while ketogenesis REQUIRES acetyl CoA
True
False
Where does ketogenesis occur?
mitochondrial matrix of liver cell
cytoplasm of liver cell
smooth ER
golgi body
Other than the liver, where can ketogenesis occur?
renal cortex
not this
Acetyl CoA is the precursor for ALL 3 ketone bodies (acetone, acetoacetate, B-hydroxybutyrate)
True
False
What joins 2 acetyl CoAs together in ketogenesis?
HMG-CoA synthase
thiolase
The first step of ketogenesis is the reverse of the last step of beta oxidation.
True
False
Formation of acetoacetyl CoA is very favorable direction of thiolase reaction.
True
False
What is the rate limiting step of ketone body synthesis?
thiolase
HMG CoA synthase
How many CoA's are freed from the formation of HMG-CoA in ketogenesis?
1
2
3
Where is the ONLY place HMG-CoA lyase is present?
mitochondrial matrix of the liver
cytosol of the liver
pancreas
CoA-SH must be removed from HMG-CoA via HMG-CoA lyase in order to traffic its products to other tissues.
True
False
Acetoacetate and B-hydroxybutyrate are products of HMG-CoA
True
False
Acetoacetate can enter the blood directly OR
be reduced to B-hydroxybutyrate
be used it beta oxidation
Which has more energy?
Acetoacetate
B-hydroxybutyrate
What causes acetoacetate to become acetone instead of B-hydroxybutyrate?
spontaneous decarboxylation
reduction reaction
What happens if acetone is formed instead of B-hydroxybutyrate?
acetone goes on to fuel TCA
acetone is volatile and exhaled in lungs
acetone is used as alternate energy source to glucose
What is sent to extrahepatic tissues to be used in energy production?
acetone
HMG-CoA
Acetoacetate and B-Hydroxybutyrate
What determines equilibrium of acetoacetate and B-hydroxybutyrate?
FADH2
ATP
NAD+/NADH ratio
NADH is higher during fasting due to increased B-oxidation.
True
False
How many B-hydroxybutyrates are made from acetoacetate?
1
2
3
How many acetones are made from acetoacetate?
1
2
3
HMG-CoA lyase is present only in the mitochondrial matrix of the liver.
True
False
The CoA-SH formed from ketogenesis can be used for
nothing...it gets exhaled
allows for B-oxidation to continue
Needed to activate FA
Need for thiolysis to generate Acetyl-CoA
Acetone from ketogenesis is used for
allows for continued B-oxidation
not usually generated under normal conditions
nothing...it gets exhaled through lungs
Causes fruity odor in mouth
Acetoacetate that is formed from ketogenesis can be used for....
gets exhaled in lungs
is not as reduced as B-hydroxybutyrate
used for energy production
sent to extrahepatic tissues
B-hydroxybutyrate that is formed in ketogenesis can be used for....
sent to extrahepatic tissues
the most reduced ketone body (has more energy)
used for energy production
Predominate ketone body that is formed (3:1)
What organ is the source for ketone bodies?
kidney
pancreas
liver
stomach
The liver is a producer of ketone bodies but it cannot consume them for energy.
True
False
The liver is ALWAYS synthesizing ketone bodies, but during fasting state, liver increases ketone body formation.
True
False
Why can't the liver USE ketone bodies for fuel?
the liver can use ketone bodies for fuel
It does not need oxygen
it lacks thiophorase to breakdown acetoacetate into 2 acetyl-CoAs
Extrahepatic tissues take in B-hydroxybutyrate from the blood and transports it to ____
the mitochondrial matrix
the cytosol
the nucleus
In the mitochondrial matrix, B-hydroxybutyrate is oxidized back to
acetoacetate
Acetone
The energy produced from acetoacetate is equal to the oxidation of 2 acetyl CoA entering the CAC
True
False
How much ATP is yielded from the oxidation of B-hydroxybutyrate?
2
32
22.5
Total ATP from glucose yields...
2
32
22.5
Ketogenic amino acids will
used to make glucose
used to make ketones
Ketogenic amino acids can be converted to Acetyl CoA or acetoacetyl CoA
true
false
Glucogenic aa can be converted into acetyl CoA.
True
False
The metabolic priority during prolonged starvation is to
maintain blood glucose levels
preserve proteins
Initially during fasting state, AA are degraded into glucogenic and ketogenic aa.
True
False
The second priority during prolonged starvation is to
maintain blood glucose levels
preserve proteins
During starvation, the body shifts from using glucose to using ___ for fuels
fatty acids
not this
What plasma levels change the most during starvation?
glucose
ketone bodies
fatty acids
The body can only use 30% of muscle for energy.
True
False
increased FA (from lypolysis) promotes hepatic ketone body synthesis during fasting
true
false
How is FA synthesis turned off during fasting?
Malonyl-CoA formation is inhibited
Carnitine shuttle is activated
TCA gets shut down during fasting. What happens to oxaloacetate?
it is used in ketone body synthesis
it gets used in gluconeogenesis
Beta oxidation is active during starvation.
True
False
Diabetic ketoacidosis results from
too much insulin and too much glucose uptake from blood
the body does not take up glucose from blood (body thinks it is starving)
overproduction of ketone bodies
ketosis
not this
ketone bodies are ____
organic bases
organic acids
Ketone bodies can ionize and release protons
True
False
ketoacidosis is when blood pH is too low and ketones are too high.
True
False
diabetic ketoacidosis results from cells not taking in glucose from the blood --> body thinks it is starving --> increased FA breakdown --> increased Acetyl CoA --> increased Acetyl CoA drives ketone body synthesis for energy since no glucose --> ketone bodies are overproduced --> ionize in the blood ---> protons are released --> blood pH drops
True
False
ketogenic diet
high carb, low fat
low carb, high fat
In ketogenic diet --> decrease glucose intake (low carb) --> body starts breaking down adipose into FA --> FA used to make acetyl CoA --> ketone bodies formed
True
False
Advantages of ketone bodies
make more energy than glucose
water soluble
can be used by heart, kidney, brain nerves, and muscles during starvation
can be used by liver
Disadvantages of ketones
not as much energy as oxidation of FA or glucose
can't be used by liver for energy
ketones are easily transported in the blood
excess ketogenesis can lead to ketoacidosis
