Lessons 3-4: Fatty Acid Metabolism

Palmitate structure

Carboxylic acid with 16 total carbons

Where in the cell does fatty acid synthesis occur?

Cytoplasm

Draw pathway of the first step of FA breakdown (activation) Include all enzymes, substrates, and energy substrates.

FA + CoA + ATP yields fatty acyl-CoA, enzyme is acyl-CoA synthetase

When the chylomicrons reach the capillaries, their TG molecules will get broken down into fatty acids via ___

Lipoprotein lipase, which is found in capillaries and activated by insulin Insulin promotes the storage of energy by activating lipoprotein lipase and activating glucose transporters. This allows these biomolecules to enter cells for storage.

Where does ketogenesis primarily occur?

Liver

After the reaction between the acetyl-CoA and malonyl-CoA on fatty acid synthase, a 4-carbon long fatty acid is left bound to fatty acid synthase. What substrate will come along next and bind to fatty acid synthase, allowing the polymerization reaction to continue?

Malonyl-CoA

Which two amino acids are strictly ketogenic?

lysine and leucine

Describe the pathway by which the amino group of an amino acid travels from a skeletal muscle cell to the bladder.

The amino group is transferred to alpha-ketoglutarate, converting it into glutamate. This reaction is catalyzed by a transaminase, which converts the amino acid into an alpha-ketoacid that can be used for energy. the glutamate carries the amino group to the liver where it is converted into urea via the urea cycle. From there, the urea travels to the kidney, where it is filtered into the bladder for excretion.

True or false? Fatty-Acyl-CoA Synthetase needs to attach a CoA group to the fatty acid before the rate-limiting step.

True

Draw out the fatty acid synthesis pathway, including all enzymes, substrates, and energy substrates.

see photo

Which of the following does bile NOT contain? (A) Lipase (B) Bile salts (C) Pigments (D) Cholesterol

(A) Lipase Bile contains Bile Salts, Pigments and Cholesterol.

The breakdown of fatty acids consists of three main steps. Put them in order from first to last: I. Oxidation II. Transportation III. Activation

III > II > I The breakdown of fatty acids consists of the following steps in order: III. Activation II. Transportation I. Oxidation

Does malonyl-CoA activate or inhibit Carnitine acyl transferase I? Why does this make sense?

Malonyl-CoA inhibits Carnitine acyl transferase I. This makes sense because malonyl-CoA is the starting substrate for fatty acid synthesis; thus, high levels of malonyl-CoA indicate that fatty acid synthesis is active. If we are building up fatty acids, we don't want to be breaking them down at the same time.

The liver will receive many of these fatty acids that are carried by albumin. Why does the liver need these fatty acids during the fasting state?

During the fasting state, the liver is working hard to produce glucose via the breakdown of glycogen. This requires energy, and the liver primarily relies on fatty acids for that energy.

One way to get Oxaloacetate back into the mitochondria is to convert it into pyruvate, which produces a molecule of NADPH. Besides activating antioxidants, what other role does NADPH play within the cell?

NADPH is used as an important reducing agent during fatty acid synthesis.

Why doesn't the liver use its own glucose for energy or use its own glucose to make its own fatty acids?

During the fasting state, the liver's job is to generate glucose for the rest of the body. Thus, the liver will upregulate processes such as gluconeogenesis and glycogenolysis while downregulating processes such as fatty acid synthesis and glycolysis.

Bile emulsifies fats. Explain what this means on a chemical level.

Fats are very non-polar, making them avoid interaction with the water in our intestines. Instead, fats will clump together. Bile is both polar and nonpolar; thus, its nonpolar regions will interact with the fats and its polar regions will interact with the water, causing the fats to be dissolved.

What two substrates initially bind to fatty acid synthase during the polymerization of a long-chain fatty acid?

Acetyl-CoA and malonyl-CoA

What allows acyl carnitine to traverse the outer mitochondrial membrane? The inner mitochondrial membrane?

Acyl carnitine is simply able to diffuse across the outer mitochondrial membrane due to its high permeability. The inner mitochondrial membrane, on the other hand, is very impermeable; thus, acyl carnitine needs to be transported across with the help of acyl carnitine translocase.

Compare the structure of acyl-CoA versus acetyl-CoA.

Acyl-CoA is a fatty acid with a CoA instead of an OH group. Acetyl-CoA is an acetyl group with a CoA attached.

It can be said that all digestion leads to the liver. Describe the path that each of the following macronutrients takes to get from the small intestine to the liver: (1) Sugars (2) Proteins (3) Fats

(1) Sugars are broken down to mono/disaccharides and are transported from enterocytes directly into capillaries that lead directly to liver (2) Proteins are broken down to amino acids and are transported from enterocytes directly into capillaries that lead directly to the liver (3) Fats are packaged into chylomicrons and then travel through the lymphatic system to veins. From there, they enter arteries and finally capillaries where they will get broken down. The leftovers known as chylomicron remnants will then get transported to the liver.

Compare the role of the following lipases: (1) Bile salt-dependent lipase (2) Lipoprotein lipase (3) Hormone-sensitive lipase

(1) Bile salt-dependent lipase - Breaks down triacylglycerol molecules in the small intestine in preparation for absorption. (2) Lipoprotein lipase - Breaks down triacylglycerol molecules in the bloodstream that are being transported by chylomicrons and VLDLs in preparation for absorption by adipocytes and other cells. (3) Hormone-sensitive lipase - Breaks down triacylglycerol molecules in adipocytes in order to transport them into the bloodstream and to the rest of the body to use for energy.

Will it activate or inhibit acetyl-CoA carboxylase? (1) Citrate (2) Glucagon (3) Fatty Acids (4) Insulin

(1) Citrate - activate (2) Glucagon - inhibit (3) Fatty Acids - inhibit (4) Insulin - activate

Let's Review -- Where does each of the following metabolic pathways take place in the cell? (1) Glycolysis (2) Gluconeogenesis (3) The Linking Step (4) The Kreb's Cycle (5) The Electron Transport Chain (6) Fatty Acid Synthesis (7) Beta-oxidation

(1) Glycolysis - Cytoplasm (2) Gluconeogenesis - Liver (3) The Linking Step - Mitochondrial Matrix (4) The Kreb's Cycle - Mitochondrial Matrix (5) The Electron Transport Chain - Inner Mitochondrial Membrane (6) Fatty Acid Synthesis - Cytoplasm (7) Beta-oxidation - Mitochondrial Matrix

Put the following steps of triacylglycerol digestion in order: I. Triacylglycerol formation II. Transport through lymphatic system III. Transport into enterocyte IV. Packaging V. Triacylglycerol breakdown VI. Transport through blood stream (A) V > III > I > IV > II > VI (B) I > III > V > IV > II > VI (C) V > III > I > IV > VI > II (D) I > III > V > IV > VI > II

(A) V > III > I > IV > II > VI The following are the steps of triacylglycerol digestion in order: V. Triacylglycerol breakdown III. Transport into enterocyte I. Triacylglycerol formation IV. Packaging II. Transport through lymphatic system VI. Transport through blood stream

Which enzyme in the fatty acid synthesis pathway catalyzes the rate-limiting step? (A) Fatty Acid Synthase (B) Acetyl-CoA Carboxylase (C) Citrate Lyase (D) Citrate Synthase

(B) Acetyl-CoA Carboxylase Acetyl-CoA carboxylase is the enzyme that catalyzes the rate-limiting step of fatty acid synthesis.

Which enzyme catalyzes the rate-limiting step of beta-oxidation? (A) Acyl Synthetase (B) Carnitine Acyl Transferase I (C) Acyl Carnitine Translocase (D) Carnitine Acyl Transferase II

(B) Carnitine Acyl Transferase I Carnitine acyl transferase I is the enzyme that catalyzes the rate-limiting step of beta-oxidation.

Which of the following statements about fatty acid synthesis is correct? (A) Fatty acids can be used to synthesize glucose. (B) Fatty acids can be synthesized from glucose. (C) Fatty acids can be broken down to generate NADPH (D) Fatty acids are important in nucleotide synthesis.

(B) Fatty acids can be synthesized from glucose. Excess glucose (from dietary carbohydrates) can be converted into acetyl-CoA, which can be used to build up fatty acids. Because the PDH reaction is irreversible, fatty acids cannot be converted back into glucose.

In the fasted state, amino acids are sent to the ___________ where they are converted into glucose via gluconeogenesis. (A) Spleen (B) Liver (C) Pancreas (D) Kidney

(B) Liver

Which of the following is NOT another type of dietary fat? (A) Cholesterol (B) Free fatty acids (C) Glycerol (D) Phospholipids

(C) Glycerol Other types of dietary fat include Cholesterol, Cholesterol Esters, Phospholipids and Free Fatty Acids.

VLDLs will transport the Triacylglycerols to various cells. What do you call the remains of the VLDL molecule? (A) HDL (B) LDL (C) IDL (D) MDL

(C) IDL IDL (Intermediate Density Lipoprotein) is the remnants of VLDL, and is typically reabsorbed at the liver or used by the blood to become LDL.

In the liver, fatty acids synthesized from glucose can be packaged with the chylomicron remnants to form: (A) HDLs (B) Chylomicrons (C) VLDLs (D) Albumin

(C) VLDLs

If a 20-carbon long fatty acid is synthesized from 10 acetyl-CoA molecules, ___ ATP and ___ NADPH will be required. (A) 10, 10 (B) 10, 20 (C) 9, 9 (D) 9, 18

(D) 9, 18 If a 20-carbon long fatty acid is synthesized from 10 acetyl-CoA molecules, 9 ATP and 18 NADPH will be required.

The fatty acids generated by hormone-sensitive lipase will travel through the bloodstream to their target tissues via: (A) VLDLs (B) HDLs (C) Chylomicrons (D) Albumin

(D) Albumin

Which of the following statements about LDL and HDL is FALSE? (A) LDL and HDL are both mainly composed of cholesterol. (B) HDL is associated with apolipoproteins that will recover excess cholesterol from the blood vessels. (C) LDL is associated with most of the cholesterol measured in the blood, and delivers cholesterol to cells. (D) None of the above statements are false.

(D) None of the above statements are false. Each of the following statements is true

The excess acetyl-CoA molecules in the fasting state are used to produce: (A) fatty acids (B) amino acids (C) glycogen (D) ketones

(D) ketones The excess acetyl-CoA molecules in the fasting state are used to produce ketones. In the fed state, these excess acetyl-CoA can be used to create fatty acid stores.

Is fatty acid synthesis activated or inhibited by the following hormones? -Insulin -Glucagon -Epinephrine

-Insulin promotes FA synthesis -Glucagon inhibits FA synthesis -Epinephrine inhibits FA synthesis A couple of hours after a meal, insulin levels begin to fall, and its opposing hormones, glucagon and epinephrine, are released into the bloodstream. The decrease in the level of insulin and increase in the levels of glucagon and epinephrine sends signals to adipose cells, via hormone receptors and various modifications of intracellular enzymes, to release fatty acids into the bloodstream. These fatty acids are then delivered to various tissues as a fuel source and broken down to produce energy.

Draw pathway of the third step of FA breakdown (beta-oxidation) Include enzymes, substrates, and energy substrates.

4 steps: dehydrogenation, hydration, dehydrogenation, acylation

What would happen to the body's ability to digest fats if the gall bladder stopped secreting bile into the small intestine?

Bile causes fats to be broken down into smaller chunks that are able to be digested and absorbed. Without bile, fat droplets would pass through without being absorbed

Draw pathway of the second step of FA breakdown (transportation) Include all enzymes, substrates, and energy substrates.

Carnitine shuttle across inner mitochondrial membrane; see photo

Before being transported into the lymphatic system from the enterocyte (intestinal cell), triacylglycerides are packaged into chylomicrons. Describe the structure of a chylomicron.

Chylomicrons consist of lipoproteins and fatty acids which form a bubble around triacylglycerides and other fats.

What bonds hold triglycerides together

Ester bonds, they bind each acyl group to the glycerol backbone

True or False? When fasting, fatty oxidation is upregulated due to an increase in glucagon and a decrease in insulin. After several days, however, as levels of acetyl-CoA rise, beta-oxidation is inhibited.

False. Beta-oxidation is not downregulated due to the presence of acetyl-CoA. This allows fatty acid levels to continue rising.

True or false? Isomerases and Reductases are both needed for monounsaturated fatty acids to undergo Beta-Oxidation.

False. Isomerases are needed for monounsaturated fatty acids to undergo Beta-Oxidation. Reductase enzymes are not needed unless the fatty acid is Polyunsaturated.

Why is it more efficient to store energy as lipids rather than as glycogen?

First, the energy yield per gram of lipid (about 38 kJ/g) is more than twice that for carbohydrate(about 17 kJ/g). Second, lipid is stored as anhydrous lipid droplets, but carbohydrates (such as glycogen and starch) are stored with water, which roughly triples the effective weight of carbohydrates.

Hormone-sensitive lipase will be activated by a decrease or increase in the concentration of insulin? Glucagon?

Hormone-sensitive lipase is activated during the fasting state due to decreasing levels of insulin and increasing levels of glucagon.

Which of the following are required for Acetyl-CoA Carboxylase to function? I. ATP II. Biotin III. NADH

I and II only ATP and Biotin are required for Acetyl-CoA Carboxylase to function.

Acetyl CoA carboxylase catalyzes the first, highly regulated step in fatty acid synthesis. Which of the following molecules activates acetyl CoA carboxylase? I. Citrate I. Glucagon III. Insulin

I and III Citrate and insulin activate acetyl CoA carboxylase. Citrate is a feed forward activator, as it is an earlier intermediate of acetyl CoA as part of the process of malonyl CoA formation. Glucagon and fatty acid inhibit acetyl CoA carboxylase. Fatty acids are a feedback inhibitor. When lots of fatty acids have been synthesized, they let the cell know that no more fatty acids need to be synthesized at that time.

The chylomicrons enter the lymphatic system via lacteals. They will travel and empty into veins via which of the following: I. Right Thoracic Duct II. Central Thoracic Duct III. Left Thoracic Duct

I and III Only The chylomicrons will empty into the bloodstream via the right and left thoracic duct.

Which of the following ketones are most commonly used as energy sources in various tissues? I. Acetoacetate II. 3-Hydroxyacetone III. 3-Hydroxybutyrate

I and III only Acetoacetate and 3-Hydroxybutyrate are the most common ketones used for energy by various tissues.

Amino acids can be used to make which of the following? I. Protein II. Glucose III. Fatty Acids

I, II, and III Amino acids can be used to make protein, glucose, or fatty acids.

Match each of the following conditions to the length of the fatty acid. I. 2-12 Carbons II. 14-20 Carbons III. >20 Carbons (A) Must be oxidized elsewhere. (B) Can freely diffuse into the mitochondria (C) Must use a Carnitine Shuttle to enter Mitochondria.

I. 2-12 Carbons - (B) Can freely diffuse into the mitochondria II. 14-20 Carbons - (C) Must use a Carnitine Shuttle to enter Mitochondria. III. >20 Carbons - (A) Must be oxidized elsewhere.

Fatty acids with odd numbers of carbons must also be Oxidized for energy. Which of the following statements about this oxidation are true? I. In the first cycle, instead of an Acetyl CoA being formed, a Propionyl-CoA will be formed. II. Propionyl-CoA can be converted into Succinyl-CoA using vitamins B7 and B12. III. Succinyl-CoA can be converted to Malate and enter Gluconeogenesis.

II and III only True statements about the oxidation of odd-C fatty acids: I. In the final cycle, instead of 2 Acetyl CoA being formed, 1 Acetyl CoA and 1 Propionyl-CoA (3C) will be formed. II. Propionyl-CoA can be converted into Succinyl-CoA using vitamins B7 and B12. III. Succinyl-CoA can be converted to Malate and enter Gluconeogenesis.

Define where/when and what is transported by each of the following vehicles for lipid transport: LDL HDL VLDL Chylomicrons

LDL- As cells remove triglycerides from VLDL, it becomes IDL, followed by smaller, cholesterol-rich LDL HDL- Circulating LDL in the bloodstream exchanges components with HDL, which is synthesized in the liver. In exchange for excess cholesterol, HDL donates apolipoproteins to the LDL VLDL- is synthesized by the liver; transports TGs from the liver to the body's cells Chylomicrons- transports TGs from intestines to liver

Where do each of these reactions take place? -Fatty acid oxidation -Fatty acid synthesis

Oxidation occurs in the mitochondria; synthesis occurs in the cytoplasm Both of these processes require the transport of fatty acid components between the cytoplasm and the mitochondria.

True or false? The product of Acetyl-CoA Carboxylase is the Malonyl-CoA that will be used in Fatty Acid Synthesis.

True

True or false? When being transported into the Enterocyte (intestinal epithelium), the Free fatty acids, cholesterol, and bile salts are in Micelle form.

True

True or False? After the fatty acids are absorbed by adipocytes, they are reconverted back into triacylglycerides.

True Triacylglycerol molecules are too large to diffuse through membranes and need to be broken down into fatty acids to be transported

T/F: Fatty acid synthesis begins from the methyl end and proceeds toward the carboxylic acid end.

True. Its synthesis begins from the methyl end and proceeds toward the carboxylic acid end. Thus, C16 and C15 are added first and C2 and C1 are added last. C15 and C16 are derived directly from acetyl CoA. For further 2-carbon additions, acetyl CoA is first activated to malonyl CoA, a 3-carbon compound, by the addition of a CO2.

Because acetyl-CoA is the building block for fatty acid synthesis, we need to shuttle acetyl-CoA from the mitochondrial matrix into the cytoplasm. This is done via the ______ shuttle

Via the citrate shuttle

Glucose metabolism and fatty acid synthesis are connected by a shuttle system. Which of the following leaves the mitochondria during the synthesis of palmitic acid from glucose? a) Citrate b) Pyruvate c) Malate d) Oxaloacetate

a) Citrate Acetyl CoA cannot directly cross the mitochondrial membrane and enter the cytosol to be used for the process of fatty acid synthesis. Thus, acetyl CoA and oxaloacetate condense to form citrate. Citrate is able to cross the mitochondrial membrane. Citrate, once in the cytosol, is converted back into oxaloacetate and acetyl CoA to begin the process of fatty acid synthesis.

Fatty acid breakdown is a highly regulated process. Which of the following is an inhibitor of its rate limiting step? a) Malonyl CoA b) Succinyl CoA c) Oxaloacetate d) Acetyl CoA

a) Malonyl CoA The rate limiting step of fatty acid breakdown is the formation of acyl carnitine by acyl carnitine transferase I, an enzyme located on the outer membrane of the mitochondria. Cytosolic malonyl CoA, an intermediate involved in fatty acid synthesis, is an allosteric inhibitor of acyl carnitine transferase I. This is important, because your body does not want to be synthesizing and breaking down fatty acids at the same time. By using a substrate of fatty acid synthesis to inhibit fatty acid oxidation, the human body has essentially made these two processes mutually exclusive.

Palmitic acid is a fatty acid broken down by β-oxidation to ultimately generate ATP. The breakdown of one molecule of palmitic acid will release 8 molecules of acetyl CoA and how many molecules each of NADH and FADH₂? a) 16 NADH and 16 FADH₂ b) 7 NADH and 7 FADH₂ c) 8 NADH and 16 FADH₂ d) 8 NADH and 8 FADH₂

b) 7 NADH and 7 FADH₂ The series of four reactions of β-oxidation is repeated (n/2)-1 times for even numbered fatty acid chains, where "n" is the number of carbons (which is 16 for palmitic acid). This produces one NADH and one FADH₂ per cycle, so 7 each for 7 cycles.

Biotin is an important cofactor in many of the human body's metabolic processes. Which of the following enzymes involved in fatty acid synthesis relies upon biotin as a cofactor? a) Malonyl transacylase b) Acetyl CoA carboxylase c) Malonyl CoA carboxylase d) Acetyl transacylase

b) Acetyl CoA carboxylase Acetyl CoA carboxylase, which catalyzes the rate limiting step in fatty acid synthesis, relies upon biotin as a cofactor to carry out its function. In this step of fatty acid synthesis, carbon dioxide, biotin, and acetyl CoA carboxylase form a complex. Biotin is important because it allows the binding of the carbon dioxide, which ultimately transfers to the acetyl CoA molecule to make malonyl CoA. The other answer choices provided do not have cofactors.

In short bowel syndrome, fat cannot be properly absorbed, so long-chain fatty acids are mobilized from adipose tissue to generate energy for cell survival. The initiating substrate for this fatty acid oxidation is which of the following? a) Long chain fatty acid b) Fatty acyl CoA c) Fatty acyl carnitine d) Acetyl CoA

b) Fatty acyl CoA Long-chain fatty acids are released from adipose cells and must be activated and transported into mitochondria for oxidation. Fatty acyl CoA reacts with carnitine, forming fatty acyl carnitine, which crosses the inner mitochondrial membrane. The acyl group is then transferred back to CoA, forming fatty acyl CoA in the mitochondrial matrix. Fatty acyl CoA is thus the initiating substrate for fatty acid oxidation. The end product of fatty acid oxidation is acetyl CoA, which is oxidized via the TCA cycle and oxidative phosphorylation to produce carbon dioxide, water, and ATP.

To form triacylglycerol from diacylglycerol, which of the following compounds is required? a) Acetyl CoA b) Glycerol c) Fatty acyl CoA d) Glycerol 3-phosphate

c) Fatty acyl CoA Triacylglycerol is formed when a diacylglycerol reacts with a fatty acyl CoA. Glycerol and glycerol 3-phosphate form the backbone of the triacylglycerol. Acetyl CoA is involved in fatty acid synthesis, and not directly in triacylglycerol synthesis

As part of fatty acid transport, fatty acids, cholesterol, and bile salts are transported together to the intestinal epithelium. What form do these fatty acids, cholesterol, and bile salts take? a) Chylomicrons b) Triglycerides c) Micelles d) Chylomicron remnants

c) Micelles When transported into the enterocyte (intestinal epithelium), the fatty acids, cholesterol, and bile salts are in micelle form. When fatty acids leave the enterocyte, they are in chylomicron form. As chylomicrons are broken down by lipoprotein lipase in the bloodstream before transport to the liver, they become chylomicron remnants. Triglycerides are contained within the chylomicron and chylomicron remnants, but they are not themselves the unit of transport.

Fatty acid synthesis is a multi-step process that involves many important enzymes and intermediates. The first irreversible step in fatty acid synthesis is catalyzed by which of the following? a) Glucose 6-phosphate dehydrogenase b) Fatty acid synthase c) Malonyl CoA carboxylase d) Acetyl CoA carboxylase

d) Acetyl CoA carboxylase Fatty acids are synthesized from acetyl CoA. The first step of fatty acid synthesis is the carboxylation of acetyl CoA to form malonyl CoA by acetyl coa carboxylase. This is a highly regulated and irreversible step in fatty acid synthesis: the rate of this reaction is increased by citrate and inhibited by long-chain fatty acyl CoA. Once malonyl CoA has been formed, fatty acid synthase then sequentially adds 7 malonyl CoA molecules to acetyl CoA to form 16 C palmitate

Bile secreted by the gallbladder emulsifies fats, allowing them to be absorbed by the small intestine. Which of the following is not a component of bile? a) Salts b) Cholesterol c) Phospholipids d) Lipase

d) Lipase Bile contains salts, phospholipids, and cholesterol. These three components of bile allow it to have both hydrophilic and hydrophobic functional groups. This, in turn, gives bile the ability to solubilize, or "emulsify," amphipathic fatty molecules. Lipase is a type of protein produced by the pancreas, not the gallbladder, as part of the digestive process. Bile does not contain lipase.

Palmitate, the primary product of fatty acid synthesis, can be modified or desaturated to form other fatty acids. Where in the cell does this occur? a) Rough endoplasmic reticulum b) Golgi body c) Mitochondria d) Smooth endoplasmic reticulum

d) Smooth endoplasmic reticulum Fatty acid modification occurs in the smooth endoplasmic reticulum of the cell. Elongases and desaturases catalyze this process, while acetyl CoA carboxylase is responsible for de novo fatty acid synthesis. As with de novo fatty acid synthesis, new carbons are added in the form of malonyl CoA. It is also important to note that mammals cannot incorporate a double bond beyond carbon-9 in fatty acids.

β-oxidation of odd-chain fatty acids results in the production of propionyl CoA. This enters the citric acid cycle after conversion to which of the following? a) Oxaloacetate b) Citrate c) Acetyl CoA d) Succinyl CoA

d) Succinyl CoA β-oxidation of odd chain fatty acids leaves a 3-carbon molecule - propionyl CoA. This propionyl CoA is oxidized to form succinyl CoA via a special set of enzymes. It then enters the TCA cycle.

What is the primary role of carnitine? a) Activation of long-chain fatty acids in the cytosol b) Breakdown of odd-chain, but not even-chain fatty acids c) Breakdown of even-chain, but not odd-chain fatty acids d) Transport of acyl groups across the inner mitochondrial membrane

d) Transport of acyl groups across the inner mitochondrial membrane In the outer mitochondrial membrane, carnitine reacts with activated fatty acyl CoA to form fatty acyl carnitine, which can then pass to the inner mitochondrial membrane. Therefore, carnitine is important for the transport of fatty acyl CoA from the cytosol to the mitochondria and allows for β-oxidation to occur. Carnitine is not involved in the activation or oxidation steps of FA oxidation.

Triacylglyceride molecules can be broken down into glycerol and fatty acids. Glycerol can be broken down for use as energy via ______ and fatty acid chains can be broken down for use as energy via _____.

glycolysis, beta-oxidation Glycerol can be broken down for use as energy via glycolysis and fatty acid chains can be broken down for use as energy via beta-oxidation.

Draw the pathway for transporting acetyl-CoA into the cytoplasm for fatty acid synthesis (citrate shuttle), including all the enzymes, substrates, and energy substrates.

see photo