Essential Fatty Acids Flashcards
Are glycerophospholipids saturated?
Glycerophospholipids in membranes contain a saturated and an unsaturated fatty acid
What is contained in a glycerophospholipid?
In position 1: a saturated fatty acid mostly with 16 or 18 carbons
In position 2: An unsaturated fatty acid with 16, 18, 20 or 22 carbons containing one or more double bonds
What does MUFA mean?
Monounsaturated fatty acid
What does PUFA mean?
Polyunsaturated fatty acid
How does chain length and double bonds affect melting points?
The melting points of fatty acids increases with chain length and decreases with double bonds
How many single carbon to double carbon ratio in stearic acid? What is the melting point?
18:0 melting point- 70 degrees Celsius
What is the single carbon bind to double bond ratio of palmitic acid? What is the melting point?
16:0
Melting point- 63 degrees Celsius
What is the single carbon bind to double bond ratio of oleic acid? What is the melting point?
18:1
13 degrees Celsius
What is the single carbon bind to double bond ratio of palmitoleic acid ? What is the melting point?
16:1
1 degrees Celsius
What is the single carbon bind to double bond ratio of linoleic acid?what is the melting point?
18: 2
- 5 degrees Celsius
What is the single carbon bind to double bond ratio of a-linolenic acid? What is the me,ting point?
18: 3
- 11 degrees Celsius(comeback)
Explain the desaturation of fatty acids in humans
Desaturation of fatty acids is restricted in animals
-Humans can introduce a double bond between carbons 9 and 10. And form 🔼9
Ex. Oleic acid (18:1) is formed in humans from stearic acid (18:0)
Why can fatty acids be grouped into specific families?
Animals cannot form double bonds beyond 🔼9 toward the methyl end and that is why fatty acids can be grouped into specific families
What determines the fatty acid family?
The family is determined by counting backwards from the last carbon , independent of the length of the fatty acid until the first double bond is reached. This number will determine the w-family
a-linolenic is shown which. Is of the w-3 (n-3 ) family
How can animals form longer chain fatty acids?
Animals can introduce double bonds between 🔼9 and the carboxyl end and form longer fatty acids of the same family. But they cannot change the family
What can linoleic acid be used to form?
Linoleic acid 18:2, w6 can be used to form arachidonic acid 20:4, w6
Food rich in w6 fatty acids- nuts, avacado and corn
What can a-linolenic (w3) can be used to form?
a-linoleic acid (w3) can be used in humans to synthesize EPA and DHA which are found in biomembranes
Fish eat algae and form EPA and DHA
a-linoleic acid 18:3, w3 —> EPA(eicosapentaenoic acid 20:5, w3)- - >. DHA( docosahexaenoic acid 22:6, w3
What is the purpose of TAG synthesis in hepatocytes?
Fatty acid synthesis and TAG synthesis for release into the blood inside of VLDL for fatty acid usage by other tissues
What is the purpose of TAG. degradation in adipocytes?
Fatty acids generated from TAG degradation in lipoproteins are taken up and are stored in form of TAGs. This benefits the whole body during fatty acid synthesis
Outline TAG synthesis in fat cells and hepatocytes
Glycolysis and glycerol (only liver) go to form glycerol 3-p
Glycerol 3-p And 2 fatty acyl CoAs form phosphatidic acid
Phosphatidic acid forms Pi and DAG
DAG uses 1 fatty acyl CoA to form TAG
What is the MAG pathway for TAG synthesis?
Only in intestinal mucousal cells
MAG formed by pancreatic lipase
Fatty acid CoA along with MAG form DAG
DAG along with fatty acyl CoA form TAG
What effect does high blood glucose and insulin have on TAG?
Increases TAG synthesis
How does epinephrine effect TAG?
Epinephrine —> fight and flight (cAMP) lead to TAG degradation
How does epinephrine lead to TAG degradation in fat cells?
Epinephrine via cAMP/protein kinase pathway leads to phosphorylation of and activation of hormone sensitive lipase (HLP) in fat cells. This leads to TAG degradation and release of glycerol and free fatty acids into the blood
How are free fatty acids transported in the blood?
Free fatty acids aren’t water soluble and they are transported by albumin in hydrophobic pockets
-Albumin stays in the blood when fatty acids enter the cells
What is the preferred fuel for heart and oxygenated muscle?
Fatty acids are the preferred fuel for energy generation in heart and oxygenated resting muscle
When does liver need fatty acid oxidation?
The liver fatty acid oxidation during fasting for energy generation and for allosteric regulation to perform gluconeogenesis
How does fatty acyl CoA synthetase (thiokinase) synthesize fatty acyl-CoA ?
The enzyme uses a free fatty acid, free CoA and ATP as substrates and forms fatty acyl CoA
The overall reaction is irreversible
- ATP is cleaved to AMP+ PPi
- PPi is immediately cleaved to 2
Totally 2 energy-rich bonds are cleaved which is counted often as 2 ATP
What is free fatty acyl CoA used for ?
The free CoA pool is limited and the rapid turnover of fatty acyl CoAs is needed to generate free CoA again
Used in :
Energy (B-oxidation keto genesis )
Storage (triacylglycerols)
Membrane lipids (phospholipids, sphingolipids)
What is the Carnitine shuttle?
- Fatty acids are activated to fatty acyl CoA at the outer mitochondrial membrane. They cannot pass the inner mitochondrial membrane for fatty acid degradation in mitochondria because they contain the bound CoA.
- The carnitine shuttle transfers the long-chain fatty acyl groups (16-20C) as carnitine esters into the mitochondrial matrix for degradation by B-oxidation
Outline the carnitine shuttle
- Fatty acyl CoA cannot pass the inner mitochondrial membrane therefore fatty acyl carnitine is formed by carnitine palmitoyl transferase 1 (CTP 1)
- Fatty acyl carnitine is transferred through the inner mitochondrial membrane into the mitochondrial matrix by a translocase which transfers at the same time free carnitine out of the matrix (like a revolving door)
- In the mitochondrial matrix, fatty acyl carnitine and free CoA are used to form again fatty acyl CoA by carnitine palmitoyl transferase II
What is the site of synthesis, location of action and activation method of Hormone sensitive-lipase?
Site of synthesis: fat cells
Location of action: fat cells
Special: this lipase is only active when phosphorylated by protein kinase A
Activation method:phosphorylation following epinephrine action
Active inside of fat cells at low serum insulin and high epinephrine levels
What is the site of synthesis, location of action, and activation method of pancreatic lipase?
Site of synthesis: pancreatic cells
Location of action: intestinal lumen
Special dietary TAG is only degraded to MAG and 2 fatty acids
Activation method: TAGs, bile salts, colipase
Active after a meal in the intestinal lumen and released by CCK from the pancreas
