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67 Cards in this Set

  • Front
  • Back
What are fatty acids?
Monocarboxylic acid with varying degrees of carbon (or alkyl) groups terminating in a carboxyl group
How are fatty acids classified?
classified by the length of their chain
Short chain: 1-4 Carbons
Medium chain: 5-12 carbons
Long chain: 13-22 carbons
very long chains: 22+ carbons
What are the 8 major saturated fatty acids?
Butyric acid
Caproic acid
Caprylic acid
Capric acid
Lauric acid
Myristic acid
Palmitic acid
Stearic acid
what does Butyric acid do?
plays critical role in colon health
Lowers serum cholesterol
what does Caproic acid do?
lowers serum cholesterol
what does Caprylic acid do?
lowers serum cholesterol
what does Capric acid do?
lowers serum cholesterol
what three major saturated fatty acids increase serum cholesterol?
Lauric acid
Myristic acid
Palmitic acid
what does Lauric acid do?
first of three most widely distributed fatty acids
Raises serum cholesterol
important in anti-infection factor in milk
what does Myristic acid do?
second most widely distributed fatty acid
Strongly raises serum cholesterol levels
what does Palmitic acid do?
third most widely distributred fatty acid
Major fatty acid that humans synthesize
Strongly raises serum cholesterol levels
what does Stearic acid do?
Cocoa is 40% (milk 5% and lard 10%)
Lowers serum cholesterol
What two monosaturated fatty acids play a major role in our health?
Oelic acid
Nervoinic acid
what does Oelic acid do?
most common fatty acid found in nature
used to trap cholesterol inside human cells
what does Nervonic acid do?
the major fatty acid in brain sphingolipids
used to form Myelin
What Omega-6 polyunsaturated fatty acid is essential?
Linoleic acid
-essential omega-6 fatty acid which forms
Most common in nature
what two fatty acids are formed from Linoleic acid and then used to synthesize eicosanoids?
1. Dihomo-gamma-linoleic: precursor for anti-inflammatory eicosanoids
2. Arachadonic acid: precursors for pro-inflammatory eicosanoid synthesis
what are the symptoms of Linoleic deficiency? (Omega-6 FA)
Growth retardation
Skin lesions
Reproductive failure
Polydypsia (excessive thirst)
Fatty liver
what omega-3 fatty acid is essential?
Alpha-linolenic acid
what fatty acid is formed from Alpha-linolenic acid (Omega 3)?
1. Eicosapentaenoic (EPA): precursor for anti-inflammatory eicosanoid synthesis
2. Docohexaenoic (DHA): essential for human brain function and second most abundant in human brain
what are the signs and symptoms of an alpha-linolenic acid deficiency?
Omega-3 deficiency
effect the skin and growth
impact learning and brain function
lead to abnormal electroretinogram
impair vision
Cause polydipsia (excessive thirst)
What is the RDA for Linoleic acid (Omega-6)?
4.44 g/day with above 6.67 g/day considered potentially toxic
what is the approximate amount of Linoleic acid consumed by Americans daily?
12 g/day of linoleic acid
what is the RDA for alpha-linolenic acid (Omega 3)?
2 g/day
there is no upper limit
what is a balance between omega 6 and omega-3's important?
A balance between omega-3 and omega-6 is important because omega-3's are anti-inflammatory and omega-6's are pro-inflammatory.
Our diet is NOT providing us with enough EPA (from alpha-linolenic) to counteract the actions of arachadonic acid (from linoleic) and this can lead to the development of many different kinds of disease by increasing inflammation in our body
what should the ratio of omega-3 to omega-6 be in our diet?
The American Omega 6/3 ratio is 16
WHO recommends between 5 and 10 range for omega 6/3 ratio
Where do fatty acids come from?
fatty acids that are not soluble in water are put into chylomicrons
fatty acids that are soluble in water go directly into the blood after they are absorbed by the gut
Fatty acids released by fat tissue are NOT soluble in water so they have to be transported by albumin
fatty acids come from our diet and they also come from De novo synthesis
what two enzymes are needed to get fatty acids into and out of adipose tissue?
Hormone sensitive lipase is only found in adipose tissue
-Gets fatty acids OUT of adipose
Lipoprotein lipase is found in adipose tissue but is also found in capillary bed of skeletal muscle and heart muscle
-gets fatty acids IN adipose
how are fatty acids transported in the blood?
Fatty acids that are NOT soluble in water are transported by albumin
What 6 tissues synthesize large amounts of fatty acids?
adipose tissue
lactating mammary gland
what is used fro fatty acid synthesis?
Acetyl CoA is the source of carbon for fatty acid synthesis
it comes from glucose or amino acids
Malonyl-CoA can only be used for fatty acid synthesis
Synthesis occurs in the cytoplasm using Acetyl-CoA carboxylase
What is the rate limiting step of fatty acid synthesis?
Carboxylation of Acetyl-CoA
What is ACP?
Acyl Carrier Protein
-used to hold fatty acids during fatty acid synthesis
-uses phosphopantetheine as a prosthetic group attached to a carrier protein with a serine domain by PPTase
what are the steps of fatty acid synthesis?
1. Condensation of an acitvated acyl group with CH2 of malonyl CoA releasing malonyl CoAs free COO2 group as CO2
2. Reducation of the beta-keto group to an alcohol (uses NADPH)
3. Dehydration (elimination of water) to create a double bond
4. Reduction of the double bond to create a fatty acyl group (uses NADPH)
what inhibits fatty acid synthesis?
ACetyl-CoA Carboxylase inhibition
what is the most active state of Acetyl-CoA Carboxylase?
polymerized state is the most active state
what does phosphorylation of Acetyl-CoA carboxylase do?
phosphorylation promotes depolymerization to form the monomer state which is less active form
How does AMP regulate fatty acid synthesis?
AMP: a low energy state will activate an AMP-dependent kinase to phosphorylate Acetyl-CoA carboxylase
how does Glucagon/Epinephrine regulate fatty acid synthesis?
through regulation of Acetyl-CoA Carboxylase
The cyclic AMP dependent protein kinase will phosphorylate Acetyl-CoA carboxylase
Glucagon also inhibits gene expression for Acetyl-CoA carboxylase
how does Palmitoyl-CoA regulate fatty acid synthesis
feeds back to transform the Acetyl-CoA carboxylase from the polymerized state to the monomer state which is less active form
how does DHA & EPA regulate fatty acid synthesis?
Omega-3 Fatty acids
suppress expression of the gene that codes for acetyl-CoA carboxylase
what stimulates fatty acid synthesis?
stimulation of Acetyl-CoA carboxylase
1. Citrate
2. Insulin
how does Citrate stimulate fatty acid synthesis?
feeds forward to promote formation of the polymerized form of Acetyl-CoA carboxylase
Citrate can also make the phosphorylated monomers polymerize to form the more active enzyme
how does Insulin stimulate fatty acid synthesis?
activates a phosphatase to put Acetyl-CoA Carboxylase in the unphosphorylated form so it can polymerize to form the most active configuration
Insulin increases gene expression for Acetyl-CoA Carboxylase
how is fatty acid synthase controlled?
control is through gene expression
-SREBP-1 binds to DNA and promotes the expression of the genes that code for the four enzymes in the fatty acid synthase
how does insulin affect the SREBP-1 gene expression?
raises levels of expression in the liver
how does glucose affect the SREBP-1 gene expression for fatty acid synthase regulation?
raises levels of expression in the liver
how does Glucagon affect the SREBP-1 gene expression for fatty acid synthase regulation?
lowers SREBP-1 levels in the liver
how does DHA & EPA affect the SREBP-1 gene expression for fatty acid synthase regulation?
lowers SREBP-1 levels in the liver
how does Leptin affect the SREBP-1 gene expression for fatty acid synthase regulation?
lowers SREBP-1 levels in the adipose tissue
how do we get the Acetyl-CoA that is needed for fatty acid synthesis out of the mitochondria?
Citrate-malate-pyruvate shuttle
Where does the NADPH that is needed for fatty acid synthesis come from ?
1 NADPH is produced for every Acetyl-CoA moved through the citrate-malate-pyruvate shuttle
What 3 enzymes are used to form NADPH for fatty acid synthesis?
Malic enzyme
Glucose-6-Phosphate dehydrogenase
6-Phosphogluconate dehydrogenase
What is beta-oxidation?
Beta-oxidation is used to burn long chain fatty acids to produce Acetyl-CoA
what does Carnitine do?
Carnitine is used to burn long chain fatty acids in the mitochondria, it moves these fatty acids into the cytoplasm
It is synthesized in the liver and kidneys from Lysine
What 6 factors are required for Carnitine synthesis in the liver?
Vitamin C
Vitamin B6
how are fatty acids trapped inside the cell?
An enzyme called acyl-CoA synthase (ACS) is used to trap fatty acids in the cell
This process adds CoA onto them thus trapping them
(also called activation because it is activating them for lipid synthesis)
what are the steps involved in beta-oxidation?
1. Oxidize: using FAD only get 2 ATP performed by acyl-CoA dehydrogenase
2. Hydrate: add water performed by enoyl-CoA hydrolase
3. Oxidize: performed by hydroxyacyl CoA dehydronase
4. Cleavage: 3-ketoacyl-CoA thiolase (uses coenzyme A to cleave off acetic acid as acetyl-CoA
how is beta-oxidation regulated?
1. Malonyl-CoA coming from fatty acid synthesis will inhibit carnitine palmitoyl transferase I and prevent long chain fatty acids from getting into the mitochondrial matrix
2. Control release of Fatty acids into blood from adipose tissue by regulating the activity of hormone sensitive lipase
3. Control movement of these fatty acids into mitochondria using malonyl-CoA
4. Malonyl-CoA coming from fatty acids synthesis will inhibit beta-oxidation
5. Leptin and glucagon will stimulate beta-oxidation
6. Omega-3 fatty acids stimulate beta-oxidation in al cells
How does a Carnitine deficiency affect fatty acid synthesis?
A carnatine deficiency will make it harder for you to burn fatty acids using beta-oxidation
how are fatty acids that contain double bonds or an odd number of carbon atoms handled in the human body?
-Odd number fatty acids produce propionyl-CoA as the last product of beta-oxiadation
-This is converted to Glucose in the liver using B12 requiring enzyme
-On single double bond fatty acids an isomerase is used to convert it from a cis to a trans
-Enoyl-CoA isomerase and dienoyl-CoA isomerase are used to change cis double bonds to trans double bonds
-dienoyl-CoA reductase eliminates a double bond
what are ketone bodies and where are they produced?
A ketone body is a lower molecular weight acid
They are produced in the liver using three enzymes:
HMG-CoA synthase
HMG-CoA lyase
lots of fatty acids lead to reversal of beta oxidation which produces acetoacetyl-CoA > acetoacetic acid (ketone body)
how & where are ketone bodies used?
Used in tissue other than the liver
these tissues use beta-hydroxybutyrate dehydrogenase to convert it to acetoacetate and generate NADH which is used to form ATP
what is diabetic ketoacidosis?
An increase in the concentration of ketone bodies in the blood which decreases the pH of the blood in a process called acidosis
It occurs due to Glucagon excess and insulin insufficiency which leads to accelerated ketogenesis
How often does ketoacidosis occur?
100,000 hospital admissions a year in the US
Name 4 conditions that may cause Ketoacidosis
1. Uncontrolled Diabetes mellitus (Type I without insulin)
2. Septic shock
3. myocardial infarction type I or II
4. Pregnancy
how is ketoacidosis treated?
Insulin will work for Type I diabetics but it may not work for Type II diabetics
A type II diabetic may require oral hypoglycemic drugs