Chapter 27: Fatty Acid Degradation Flashcards
More energy is stored and extracted from FAs compared to _____. 1g of fat has _____ more energy than 1 g of glycogen.
Compared to carbohydrates
6.75 times more energy because they are reduced
Fatty acids are fuel molecules that are stored in _____ as…
Adipose tissues as Triacylglycerols (TAG)
FAs in TAG are more reduced than _____.
Monosaccharides
Fatty acid stores are good for _____ whereas glycogen is good for _____.
FAs - Several weeks
Glycogen - Days
Fatty acids in TAG stored in adipose tissue are processed in 3 stages:
- Degradation of TAG to release FAs and Glycerol into the blood for transport to other tissues
- Activation of FAs and transport into mitochondria for oxidation
- Degradation of FAs to Acetyl CoA
Degradation of FAs is in…
Mitochondria
Stage 1: Degradation of TAG
TAG –> Glycerol + FAs by lipases
TAG are stored in _____ as _____.
Adipocytes as lipid droplets
During stage 1, what stimulates lipid breakdown (lipolysis)?
Epinephrine and Glucagon
Stage 1: Adipocyte Triacylglyceride Lipase (ATGL) is activated by…
Perilipin (associated with the lipid droplet)
Stage 1: What does ATGL do?
Mobilizes TAG to FA and DAG
Stage 1: What converts diacylglycerol to FA and MAG?
Hormone sensitive-lipase (HS Lipase)
Stage 1: Monacylglycerol (MAG) lipase produces…
FA and Glycerol
Stage 2: Activation of FAs and Transport into mitochondria
Activation: Linkage of fatty acids to Coenzyme A by acyl-CoA snythetase, which occurs on mitochondrial outer membrane
Free FAs are transported to liver and muscle by…
Serum albumin complexes
Stage 2: The reaction is rendered irreversible by _____.
Pyrophosphatase
Transport into mitochondria by the _____.
Carnitine Shuttle
After activation, FA is transferred to carnitine by _____, which generates _____.
Carnitine acyltransferase I, which generates acyl carnitine
A _____ transports the acyl carnitine into the mitochondria.
Translocase
In mitochondria, _____ transfers the FA to CoA generating _____.
Carnitine acyltransferase II, generating fatty acyl CoA
What three things use FAs as a fuel?
Muscle, heart and kidney
Pathological conditions result if FAs cannot enter mitochondria due to a deficiency of _____, _____ or _____.
Carnitine, acyltransferase or translocase
Carnitine deficiencies can be treated by…
Carnitine supplementation
Stage 3: Degradation of FAs to Acetyl CoA
FA degradation consists of 4 steps that are repeated:
- Oxidation by FAD
- Hydration
- Oxidation by NAD+
- Thiolysis by CoA
The enzymes of FA oxidation are associated with each other on the _____ - ready to feed into the _____.
On the inner mitochondrial membrane - ready to feed into the ETC
What 3 things are generated by FA oxidation (Beta oxidation)?
Acetyl CoA, NADH, and FADH2
Fatty acid chain is _____ by 2 carbon atoms
Shortened
The complete oxidation of Palmitate yields…
106 molecules of ATP
What two things are required for oxidation of unsaturated FAs?
Isomerase and Reductase
Unsaturated FAs with odd-numbered double bonds require only the _____.
Isomerase
Even-numbered unsaturated FAs require…
Both the isomerase and reductase
Odd-Chain FAs yield _____ in the final thiolysis step.
Propionyl CoA
Beta-oxidation of FAs with odd numbers of carbons generates _____
Propionyl CoA in the thiolysis step
A biotin enzyme adds a carbon to propionyl CoA to form _____. What is this biotin enzyme called?
Biotin enzyme: Propionyl carboxylase
Form methylmalonyl CoA
What is formed from methylmalonyl CoA? And name the catalyst and what pathway it enters.
Succinyl CoA is formed by methylmalonyl CoA mutase and enters the TCA
What is another fuel source derived from fats?
Ketone bodies
Ketone-body synthesis (Ketogenesis) takes place in…
Liver
Excess acetyl CoA from Beta-oxidation is converted to ketone bodies made of _____ and _____ in liver mitochondria.
Acetoacetate and B-hydroxybutyrate
Ketone bodies are transported in the blood to other tissues for use as fuel and are converted to ______.
Acetyl CoA
Ketone Bodies are a crucial fuel source during _____.
Starvation
What is used during the first day of starvation?
Glycogen stores
After the 1st day of starvation, glycogen stores are exhausted and _____ become the major fuel source.
Fatty Acids
After 3 days of starvation, what % of energy need of brain is met by ketone bodies?
30%
After several weeks of starvation, ______ become the major fuel.
Ketone bodies
Ketone body se prevents _____ and avoids _____ and _____.
Prevents protein degradation and avoids tissue failure and death.
Survival time is determined by _____.
Triacylglycerol depot
Diabetes can lead to a life-threatening excess of…
Ketone-body production
During diabetes, insulin is _____ and glucose _____.
Insulin is not functioning or absent and glucose cannot be utilized.
All energy must be derived from _____, leading to the production of _____ and _____.
Fats, production of acetyl CoA and ketone bodies
Ketone bodies are moderately _____ and excess production can lead to…
Strong acids and excess can lead to acidosis, called diabetic ketosis
How many rounds of β oxidation would be required for a 16-carbon fatty acyl chain to be degraded to acetyl CoA?
7 rounds
Which of the following is NOT involved in mobilization of triacylglycerols to be used as an energy source? protein kinase A hormones such as epinephrine adipocyte triacylglycerol lipase aldehyde dehydrogenase adenylate cyclase
Aldehyde dehydrogenase
T or F: The carnitine shuttle system is a critical component of fatty acid synthesis
False; degradation
T or F: Carnitine deficiencies can result in muscle weakness.
True
T or F: In the carnitine shuttle system, it is important for transport across the inner mitochondria membrane
True
T or F: The carnitine shuttle system is needed for transport of long-chain fatty acyl CoA molecules
True
Ketone bodies are principal fuels for…
The brain during starvation
What is the correct order of reactions in the beta-oxidation cycle that is used to break down fatty acids to yield acetyl-CoA.
Oxidation, hydration, oxidation
