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60 Cards in this Set

  • Front
  • Back
16:0 represents which fatty acid?
Palmitic Acid
18:0 represents which fatty acid?
Stearic Acid
18:1 delta 9 represents which fatty acid?
Oleic Acid
18:2 delta 9,12 represents which fatty acid?
Linoleic Acid
18:3 delta 9,12,15 represents which fatty acid?
Linolenic Acid
20:4 delta 5,8,11,14 represents which fatty acid?
Arachidonic Acid
Name two essential fatty acids. Why are they essential?
Linoleic and linolenic acids are essential because they cannot be synthesized de novo, must be gained from diet.
What is the defect in MCADD?
Medium chain acyl-CoA dehydrogenase deficiency causes abnormal amounts of 8-10 carbon chain fatty acids in the circulation.
Describe the structure of a micelle.
A micelle is a unilamellar amphipathic molecule with hydrophobic lipid head groups facing outwards towards aqueous media and hydrophobic tails segregated inside.
Unsaturated fatty acids have cis or trans double bonds?
What is saponification?
lipid esters + base + heat = salts, long chain fatty acids (12-20 carbons long) + base + heat = soaps
Ingested glycerophospholipids and triglycerides are primarily broken down where?
Small Intestine
Name several enzymes that function in lipid degradation in lysosomes.
acid lipase, ceramidase, phospholipase A1 and A2, sphingomyelinase (phospholipase C), esterase, gangliosidase.
The products of lipids degraded in the cytoplasm serve as?
second messengers
Where does phospholipase A1 cleave glycerophospholipids?
the ester of the alpha chain
Where does phospholipase A2 cleave glycerophospholipids?
the ester of the beta chain
Where does phospholipase C cleave glycerophospholipids?
between the O and P of the phosphate proximal to the glycerol backbone
where does phospholipase D cleave glycerophospholipids?
between the O and P of the phosphate distal to the glycerol backbone
What is the first step in fatty acids degradation? What species and enzymes are required for it?
Activation of the fatty acid by attaching a CoA molecule via acyl-CoA sythetase (thiokinase). consumes an ATP -> AMP (equivalent of 2ATP consumed)
Where does fatty acid activation occur?
Outside of the miochondria in the cytoplasm.
How does Acyl-CoA pass through inner mitochondrial membrane?
carnitine acylcarnitine translocase
what must happen to acyl-CoA so that it can pass through inner mitochondrial membrane?
it must be esterified to carnitine by the enzyme carnitine palmitoyl transferase I
what does carnitine palmitoyl transferase II do?
it removes the carnitine from acyl-CoA so that beta oxidation can proceed
malonyl Co-A
1)precursor in fatty acid synthesis 2)inhibits carnitine palmitoyl transferase I thereby inhibiting beta oxidation of fatty acids
what is the first step of beta oxidation in the mitochondria?
acyl-CoA dehydrogenase oxidizes fatty acyl-CoA, introducing a double bond between the alpha and beta carbons and reducing an FAD+ to FADH2.
What is the second step of beta oxidation in mitochondria?
enoyl CoA hydratase adds water across the double bond to give 3-hydroxyacyl CoA
What is the third step of beta oxidation in mitochondria?
3-hydroxyacyl CoA dehydrogenase oxidizes the beta carbon, making a C=O double bond and reducing NAD+ to NADH + H
What is the fourth step of beta oxidation in mitochondria?
acetyl-CoA acetyltransferase (thiolase) adds CoA to the beta carbon giving rise to an acetyl CoA and an acyl fatty acid containing two less carbons
How many net ATP are derived from the beta oxidation of palmitoyl CoA?
106 ATP
How many NADH are derived from the beta oxidation of Stearic Acid (including those from the TCA cycle)?
How many FADH2 are derived from the beta oxidation of Stearic Acid (including those from the TCA cycle of acetyl-CoA)?
17 FADH2
Which enzyme in the beta oxidation pathway reduces an FAD+ to FADH2
Acyl-CoA dehydrogenase
Which enzyme in the beta oxidation pathway reduces a NAD+ to NADH + H?
3-hydroxyacyl CoA dehydrogenase
Where does beta oxidation of fatty acids occur?
most tissues except for the brain
Where are ketone bodies formed?
liver mitochondria
How is HMG-CoA formed?
The enzyme HMG-CoA synthase combines acetoacetyl CoA and Acetyl CoA
What happens to HMG-CoA in the fed state?
it is converted to cholesterol
What happens to HMG-CoA during fasting? Using what enzyme?
it is converted to acetoacetate via HMG-CoA lyase
The reaction of HMG-CoA with HMG-CoA lyase yields?
acetoacetate and acetyl CoA
Name the three ketone bodies created during fasting.
acetoacetate, acetone, and beta-hydroxybutyrate
How is beta-hydroxybutyrate formed?
acetoacetate reacts with beta-hydroxybutyrate reductase, consuming an NADH molecule
what happens to blood pH during starvation? why?
blood pH decreases because of the production of excessive amounts of ketone bodies
what for and where are ketone bodies used?
they are used as energy sources in extrahepatic tissues
how are ketone bodies degraded in extrahepatic tissue?
beta-hydroxybutyrate is oxidized to acetoacetate. acetoacetate is activated when succinyl-CoA donates its CoA to yield acetoacetyl-CoA and succinate. acetoacetyl-CoA requires only one enzyme (thiolase) to break into 2 Acetyl Co-A molecules that can be further metabolized to ATP via the TCA cycle.
If only thiolase enzyme is used, how many ATP are derived from one molecule of acetoacetate?
20 ATP
If the entire beta oxidation process is used on one molecule of acetoacetate, how many ATP are derived?
24 ATP
During shorter periods of fasting, what is the brain's principal source of energy? How does it differ during starvation?
During fasting, the brain consumes glucose derived from the breakdown of muscle proteins. During starvation, because the body cannot survive if the brain consumes so much muscle protein, it is forced to consume ketone bodies for energy.
During starvation, what compounds can be found in the urine?
ketone bodies
During periods of fasting, where does the heart, kidney, and other muscle derive its energy?
from the oxidation of free faty acids and from the degredation of ketone bodies
In severe uncontrolled diabetes, from what compounds is energy derived?
escessive amounts of glucose are derived from the breakdown of muscle protein to power the brain and blood and excessive amounts of fatty acids are consumed by other tissues in the form of free fatty acids and ketone bodies
Why is coma a common occurence in patients with severe uncontrolled diabetes?
Because of elevated levels of ketone bodies in the blood, ketonemia results, lowering the pH of the blood and leadin to coma.
What distinguishes starvation state from uncontrolled diabetes?
Both situations result in urine excretion of extra ketone bodies but no excess glucose is excreted in a starvation state (it is all used by the blood) like it is in diabetics.
How does beta oxidation of fatty acis containing odd numbers of carbons differ from even numbered carbon?
Beta oxidation is the same for odd numbered carbon fatty acids until a terminal 3 carbon fragment (propionyl CoA) remains. Propionyl CoA is carboxylated with propionyl-CoA carboxylase and the cofactor biotin to methylmalonyl-CoA (this step consumes an ATP) and then methylmalonyl-CoA is rearranged to succinyl CoA (an intermediate of the TCA cycle) via methylmalonyl-coA mutase and the cofactor B12.
Describe alpha oxidation of fatty acids.
RCH2COOH + monooxygenase + O2 + Fe2+ + ascorbic acid -> alpha hydroxy fatty acid (added an OH) + dehydrogenase + NAD+ -> carboxylic acid + NADH + decarboxylase + ATP + NAD+ + ascorbic acid -> RCOOH + CO2
Describe omega oxidation of fatty acids.
CH3CH2CH2COOH + NADPH + monooxygenase + O2 -> HOOCCH2CH2COOH (dicarboxylic acid) + NADP+
Describe peroxisomal degradation of long chain fatty acids.
Analagous to beta oxidation to shorten fatty acid chain, produces H2O2 in atleast one step of pathway. After partial degradation in peroxisomes, release medium chain fatty acid and beta oxidation continues in mitochondria.
What enzyme is used to conver delta 3-cis unsaturated fatty acids into delta 2-trans unsaturated fatty acids?
delta 3-cis -> delta 2-trans enoyl Co-A isomerase
What enzyme is used to convert a delta 4-cis unsaturated fatty acid into a delta 3-trans unsaturated fatty acid?
enoyl co-A reductase
Why does the degradation odd carbon number unsaturated fatty acids yield less energy than saturated fatty acids?
the isomerase enzyme used to convert cis double bonds to trans double bonds in unsaturated fatty acids fulfill the same function as acyl-CoA dehydrogenase does in normal beta oxidation, but they don't produce an FADH2
Does the degradation of even carbon number unsaturated fatty acids yield the same or less energy than saturated fatty acid of the same number of carbons? Why?
less ATP. though acyl-CoA dehydrogenase is used creating an alpha carbon double bond and producing FADH2 as in normal beta oxidation, an enoyl-CoA reductase is required to shift that the two double bonds to one beta carbon trans double bond. this process consumes an NADPH thereby reducing the amount of ATP derived from the reaction.