Exam 4 - Ch 24 Flashcards
The fat cells (adipocytes) that make up adipose tissue are capable of storing…
unlimited quantities of triacylglycerols.
Adipose tissue (made of adipocytes) stores…
85% of the total energy available in the body.
In the digestion of fats (triacylglycerols),
bile salts break fat globules into smaller particles called _____ in the small intestine.
micelles
In the digestion of fats (triacylglycerols),
pancreatic lipases hydrolyze _______ to form _______ and fatty acids, which recombine in the intestinal lining.
ester bonds
monoacylglycerols
In the digestion of fats (triacylglycerols),
____ and _____ coat the fats, forming ______, which are transported to the cells of heart, muscle, and adipose tissues.
phospholipids and proteins coat the fats, forming chylomicrons, which are transported to the cells of heart, muscle, and adipose tissues.
In the digestion of fats (triacylglycerols),
lipases hydrolyze triacylglycerols, forming glycerol and free fatty acids, which are…
oxidized to acetyl CoA molecules for ATP synthesis.
The digestion of fats begins in the small intestine when bile salts emulsify fats that undergo…
hydrolysis to monoacylglycerols and fatty acids
Triaglycerol + 2H2O (w/ pancreatic lipase catalyst) —–>
2-monoacylglycerol
When blood glucose is depleted and glycogen stores are low,
the process of fat utilization is…
stimulated.
When blood glucose is depleted and glycogen stores are low,
the hormones glucagon and epinephrine are secreted into the bloodstream, where they bind to receptors on…
the membrane of adipose tissue.
When blood glucose is depleted and glycogen stores are low,
a hormone-sensitive lipase within the fat cells….
catalyzes the hydrolysis of triacylglycerols to glycerol and free fatty acids.
When blood glucose is depleted and glycogen stores are low,
glycerol and fatty acids diffuse into the bloodstream and…
bind with plasma proteins to be transported to the tissues, muscles, and fat cells.
Glycerol from fat digestion
adds a phosphate from ATP to form…
glycerol-3-phosphate.
Glycerol from fat digestion
undergoes oxidation of the —OH group to…
dihydroxyacetone phosphate.
Glycerol from fat digestion
becomes an intermediate in…
glycolysis and gluconeogenesis.
Look at slide 6 and ensure you understand the process from glycerol all the way to dihidroxyacetone phosphate
Hope ya done it
What is the function of bile salts in fat digestion?
Bile salts break down fat globules, allowing pancreatic lipases to hydrolyze the triacylglycerol.
How is glycerol utilized?
Glycerol adds a phosphate and is oxidized to an intermediate of the glycolysis and gluconeogenesis pathways.
A large amount of energy is obtained when fatty acids undergo….
oxidation in the mitochondria to acetyl CoA.
beta oxidation (β oxidation), which removes two-carbon segments containing the alpha and beta carbon from the carboxyl end of the fatty acid.
Oxidation of Fatty Acids
A large amount of energy is obtained when fatty acids undergo:
oxidation in the mitochondria to _____
beta oxidation (β oxidation), which removes two-carbon segments containing the alpha and beta carbon from....
acetyl CoA.
….the carboxyl end of the fatty acid.
Describe the metabolic pathway of β oxidation on stearic acid:
Where does β oxidation occur?
on the β carbon! look at slide 9`
A cycle in β oxidation
produces an acetyl CoA and a fatty acid that is…
repeats until the original fatty acid is completely degraded to two-carbon units that….
…shorter by two carbons.
….form acetyl CoA, which enters the citric acid cycle.
Fatty Acid Activation:
Fatty acids in the cytosol are transported through the inner mitochondrial membrane to….
undergo β oxidation in the matrix.
Fatty Acid Activation:
In an activation process,
a fatty acid is combined with ____ to yield ___
energy is released by the hydrolysis of ___ to __ and used to drive the reaction
In an activation process,
a fatty acid is combined with CoA to yield a high-energy fatty acyl CoA.
energy is released by the hydrolysis of ATP to AMP and used to drive the reaction
LOOK AT SLIDE 11… understand the chemical reaction with enzyme Acyl CoA synthetase
Transport of Fatty Acyl CoA:
A transport system called the ______ carries fatty acids into the mitochondria from the cytosol.
carnitine shuttle
Transport of Fatty Acyl CoA:
___ _____ catalyzes the transfer of a fatty acyl group to the hydroxyl group of carnitine to produce fatty acyl carnitine.
Carnitine acyltransferase
Transport of Fatty Acyl CoA:
___ ___ ___ then passes through the inner mitochondrial membrane into the matrix.
Fatty acyl carnitine
picture on slide 13
In the matrix, another carnitine acyltransferase
catalyzes what?
then releases what?
catalyzes the reverse reaction that transfers the fatty acyl group to CoA to reform fatty acyl CoA.
releases the carnitine and returns to the cytosol.
Thus, the carnitine shuttle moves fatty acyl CoA from the cytosol into the matrix, where the fatty acid can ______
undergo β oxidation.
In the carnitine shuttle system, fatty acids are activated and transported from the ____ through the ___ ___ ___ into the ____.
In the carnitine shuttle system, fatty acids are activated and transported from the cytosol through the inner mitochondrial membrane into the matrix
Slide 15 understand the image and process of the carnitine shuttle system
SLIDE 15 !
Beta (β) Oxidation of Fatty Acids: Reaction 1, Oxidation
Fatty acyl CoA undergoes beta (β) oxidation in a cycle of….
four reactions.
Beta (β) Oxidation of Fatty Acids: Reaction 1, Oxidation
_______catalyzes the transfer of hydrogen atoms from the α and β carbons of the activated fatty acid.
a trans C = C bond is formed between α and β carbons, and…. what is produced?
acyl CoA dehydrogenase
… the reduced coenzyme FADH2 is produced.
Slide 16 look at the reaction
Beta (β) Oxidation of Fatty Acids: Reaction 1, is what type of reaction?
Oxidation
Beta (β) Oxidation of Fatty Acids: Reaction 2, Hydration
a hydration reaction catalyzed by enoyl CoA hydratase adds the components of water to the ________
a hydroxyl group (—OH) attaches to the β carbon of the fatty acid, and….
trans double bond.
….a hydrogen atom attaches to the α carbon.
Beta (β) Oxidation of Fatty Acids: Reaction 2, is what type of reaction?
Hydration
Beta (β) Oxidation of Fatty Acids: Reaction 3, Oxidation
the secondary hydroxyl group on the β carbon (carbon 3) is oxidized by ?dehydrogenase to yield a ?.
the hydrogen atoms removed in the oxidation are transferred to NAD+ to yield a β keto or 3-keto group and….
3-hydroxyacyl CoA dehydrogenase to yield a ketone.
…….the reduced coenzyme NADH.
Beta (β) Oxidation of Fatty Acids: Reaction 4, Cleavage
the Cα — Cβ bond is cleaved by β-ketoacyl CoA thiolase to yield…
the shorter fatty acyl CoA repeats the four steps of the β- oxidation cycle until….
a two-carbon acetyl CoA and a new fatty acyl CoA that is shortened by two carbon atoms.
….the original fatty acid is completely degraded to two-carbon units of acetyl CoA.
Beta (β) Oxidation of Fatty Acids: Reaction 4, is what type of reaction?
Cleavage
Fatty Acid Length Determines Cycle Repeats
The number of carbons in a fatty acid determines….
….the number of times the cycle repeats and the number of acetyl CoA units it produces.
Fatty Acid Length Determines Cycle Repeats
The total number of times the cycle repeats is one fewer than….
…the total number of acetyl groups it produces.
Fatty Acid Length Determines Cycle Repeats
Odd-numbered fatty acids go through the same four steps of β oxidation until the final cycle, in which the remaining fatty acyl CoA…
…is cleaved to yield a propionyl CoA (C3) group and an acetyl CoA.
Beta (β) Oxidation of Fatty Acids
Capric acid (C10) undergoes four oxidation cycles that repeat reactions 1 to 4 and yield…
five acetyl CoA molecules, four NADH, and four FADH2.
Oxidation of Unsaturated Fatty Acids
Some fats from our diets contain unsaturated fatty acids, which have…
one or more cis double bonds.
Oxidation of Unsaturated Fatty Acids
An isomerase converts a cis double bond to a trans double bond between the α and β carbons so…
the fatty acid can undergo hydration
Oxidation of Unsaturated Fatty Acids
It forms a product that enters β oxidation at reaction 2, so the energy released by the β oxidation of an unsaturated fatty acid is slightly less because….
… no FADH2 is produced in that cycle.
Match the reactions of β oxidation with each of the following:
Water is added.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
hydration
Match the reactions of β oxidation with each of the following:
FADH2 forms.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
oxidation 1
Match the reactions of β oxidation with each of the following:
A two-carbon unit is removed.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
acetyl CoA cleaved
Match the reactions of β oxidation with each of the following:
A hydroxyl group is oxidized.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
oxidation 2
Match the reactions of β oxidation with each of the following:
NADH forms.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
oxidation 2
How many acetyl CoA groups are produced by the complete β oxidation of palmitic acid (C16)?
1) 16
2) 8
3) 7
2) 8 (16 C/2 = 8)
How many oxidation cycles are necessary to completely oxidize palmitic acid (C16)?
1) 16
2) 8
3) 7
3) 7 (16 C/2 – 1 = 7)
Hy poglycin A is a protoxin that is metabolized to become an inhibitor of acyl CoA dehydrogenase, the
first enzyme in the b oxidation pathway.
Calculate the total ATP produced by the complete oxidation of a fatty acid.
Can you do this?
Th e energy yield from a fatty acid changes with the number of β oxidation cycles needed for its oxidation. Each cycle
- requires an initial input of ___
- produces these three…
produces one acetyl CoA that enters the citric acid cycle,
generating…
- requires an initial input of two ATP.
- produces an NADH, an FADH2, and one acetyl CoA.
produces one acetyl CoA that enters the citric acid cycle,
generating 10 ATP.
ATP from Fatty Acid Oxidation
NADH generates energy for the synthesis of
2.5 ATP.
ATP from Fatty Acid Oxidation
FADH2 provides energy for the synthesis of
1.5 ATP.
Each β oxidation cycles produces
4.0 ATP = 2.5 from NADH and 1.5 from FADH2
ATP from β Oxidation, Capric Acid
Look at this table
done
Hy poglycin A is a molecule found in high concentrations in unripe ackee fruit, the national fruit of Jamaica. This molecule is a protoxin, meaning that it becomes a toxin when it is metabolized in the body. The metabolized version of hypoglycin A is an inhibitor of acyl CoA dehydrogenase, the first enzyme in the b oxidation pathway.
Ripened ackee fruit does not contain high levels of hypoglycin A.
The illness associated with ingesting hypoglycin A is known as Jamaican vomiting sickness. Because b oxidation is inhibited, people who suffer from this illness are forced to rely on their…
glucose and glycogen reserves to provide energy for ATP synthesis.
If carbohydrates are not available,
- fatty acids break down to meet energy needs.
* acetyl CoA molecules combine to form ketone bodies.
When large quantities of fatty acids are degraded,
• too much acetyl CoA is produced. • high levels of acetyl CoA accumulate in the liver.
• acetyl CoA molecules combine in a pathway known as
ketogenesis to form compounds called ketone bodies.
24.4 Ketogenesis and Ketone Bodies
Reaction 1: Condensation
In ketogenesis,
- two molecules of acetyl CoA combine to form…
- this condensation is in the opposite direction of the last step of β oxidation.
acetoacetyl CoA and HS—CoA.
24.4 Ketogenesis and Ketone Bodies
The hydrolysis of acetoacetyl CoA
• forms acetoacetate, a ketone body, and HS— CoA.
Acetoacetate can undergo either a hydrogenation or a decarboxylation (reactions 3 and 4) to produce other ketone bodies.
Reaction 2: Hydrolysis
24.4 Ketogenesis and Ketone Bodies
Ac etoacetate is reduced by 2H from NADH + H+ to β-hydroxybutyrate, which is considered a ketone body even though it does not contain a keto group.
Reaction 3: Hydrogenation
24.4 Ketogenesis and Ketone Bodies
Ac etoacetate can also undergo decarboxylation to yield acetone, a ketone body, and CO2.
Reaction 4: Decarboxylation
- in cases of diabetes, diets high in fat, and starvation.
- as ketone bodies accumulate.
- when acidic ketone bodies lower blood pH below 7.4 (acidosis).
Ketosis occurs
• insulin does not function
properly.
• glucose levels are insufficient
for energy needs.
• fats are broken down to
acetyl CoA.
• ketogenesis produces
ketone bodies.
In diabetes,
- is characterized by the pancreas producing inadequate levels of insulin.
- can result from pancreatic damage by viral infections or from genetic mutations.
Type 1 , insulin-dependent diabetes, which often begins in childhood,
- insulin is produced, but insulin receptors are not responsive.
- a person will not respond to insulin therapy.
In type 2, insulin-resistant diabetes, characteristic of adults,
• insufficient amounts of glucose are available in the
muscle, liver, and adipose tissue.
• liver cells synthesize glucose from noncarbohydrate
sources via gluconeogenesis (fatty acid degradation),
which elevates levels of acetyl CoA.
• excess acetyl CoA undergoes ketogenesis, and ketone
bodies accumulate in the blood.
• a person with uncontrolled diabetes can go into ketosis.
In all types of diabetes,
The digestion of fats begins in the small intestine when bile salts emulsify fats that undergo
hydrolysis to monoacylglycerols and fatty acids.
Bile salts secreted from the liver and stored in gallbladder are released into the duodenum, where they coat and emulsify large fat droplets into smaller droplets, thus increasing the overall surface area of the fat, which allows the lipase to break apart the fat more effectively.
Cliff Claven?
the process of fat utilization is stimulated when…
blood glucose is depleted and glycogen stores are low
the hormones glucagon and epinephrine are secreted into the bloodstream, where they bind to receptors on the membrane of adipose tissue. This occurs when…
WHEN… blood glucose is depleted and glycogen stores are low
a hormone-sensitive lipase within the fat cells catalyzes the hydrolysis of triacylglycerols to glycerol and free fatty acids.
thanks to glucagon and epi
glycerol and fatty acids diffuse into the bloodstream and bind with plasma proteins to be transported to the tissues, muscles, and fat cells.
glycerol and free fatty acids.
from the hydrolysis of triacyglycerols
Glycerol from fat digestion
adds. ..
undergoes. ..
becomes. ..
adds a phosphate from ATP to form glycerol-3-phosphate.
undergoes oxidation of the —OH group to dihydroxyacetone phosphate.
becomes an intermediate in glycolysis and gluconeogenesis.
Look at slide 6 to understand Dihydroxyacetone phosphate and it’s link to glycolysis AND gluconeogenesis
YUP
Fatty acids in the cytosol are transported through the inner mitochondrial membrane to undergo
β oxidation in the matrix.
Fatty Acid Activation
In an activation process,
a fatty acid is combined with ___ to yield ___
energy is released by the hydrolysis of….
CoA to yield a high-energy fatty acyl CoA.
….ATP to AMP and used to drive the reaction.
Fatty Acid + ATP + HS—CoA —–> ?
Fatty Acid + ATP + HS—CoA —–> Fatty acyl CoA + AMP + 2Pi + H2O
A transport system called the ___ ____ carries fatty acids into the mitochondria from the cytosol.
carnitine shuttle
What is the carnitine shuttle?
A transport system called the carnitine shuttle carries fatty acids into the mitochondria from the cytosol.
Carnitine acyltransferase catalyzes the transfer of a fatty acyl group to the __ to produce ___
hydroxyl group of carnitine to produce fatty acyl carnitine.
Transport of Fatty Acyl CoA (continued)
After carnitine acyltransferase heps produce fatty acyl carnitine,
Fatty acyl carnitine then…
…passes through the inner mitochondrial membrane into the matrix.
Transport of Fatty Acyl CoA (continued)
In the matrix, another carnitine acyltransferase
catalyzes the reverse reaction that transfers the ___ to ___ to reform _____
releases the ___ and ___ to the _____
catalyzes the reverse reaction that transfers the fatty acyl group to CoA to reform fatty acyl CoA.
releases the carnitine and returns to the cytosol.
Thus, the carnitine shuttle moves fatty acyl CoA from the cytosol into the matrix, where….
the fatty acid can undergo β oxidation.
Fatty acyl CoA undergoes beta (β) oxidation in a cycle of four reactions.
FINISH THIS SLIDE
