Where do we get fatty acids from?
Synthesis (from excess carbohydrates and protein components, acetyl coenzyme A)
Where does fatty acid synthesis happen?
Lactating mammary gland
What part of the cell does fatty acid synthesis happen?
Where is acetyl coenzyme formed?
Why does acetyl conezyme A need to be transfered from the mitochondrial matrix for fatty acid synthesis?
Fatty acid synthesis happens in the cytosol
Can acetyl coenzyme A cross the mitochondrial membrane?
No, only the acetyl part can cross by using the citrate shuttle
How does acetyl cross the mitochondrial membrane?
By using the citrate shuttle
What is the process of the citrate shuttle?
- Acetyl coenzyme A reacts with oxaloacetate to become citrate which crosses the membrane
- In the cytosol citrate becomes is broken down into oxaloacetate and acetyl coenzyme A is released
- Oxaloacetate uses NADH to become malate
- Malate uses NADP+ to become pyruvate which crosses into the mitochondria membrane
- Pyruvate is converted into oxaloacetate to be used again
When does the citrate shuttle happen?
When citrate concentration in the mitochondria is high
What is made during the citrate shuttle that is later used in the synthesis of fatty acids?
What enzymes are involved in fatty acid synthesis?
Acetyl coenzyme A carboxylase
Fatty acid synthase
What does acetyl coenzyme A carboxylase do in the synthesis of fatty acids?
Acts as an activator/regulator
What does fatty acid synthase do in the synthesis of fatty acids?
Acts as a multifunctional enzyme
What does fatty acid synthesis need?
Acetyl coenzyme A
What is the product of fatty acid synthesis?
What is acetyl coenzyme A carboxylase needed for the formation of?
Melanyl coenzyme A
What is both the rate determining and commited step in fatty acid synthesis?
Acetyl coenzyme A + ATP → malonyl coenzyme A
How is acetyl coenzyme A carboxylase regulated?
Activated by insulin (signal enough glucose so make fatty acid), insulin
Inhibited by palmitoyl coenzyme A (enough fatty acid) glucagon, noradrenaline
What hormone activates acetyl coenzyme A carboxylase?
What hormone and neurotransmitter inhibits acetyl coenzyme A carboxylase?
Glucagon and noradrenaline
How many reactions are in the synthesis of fatty acid?
A lot, more than 7
What does fatty acid synthesis form and what is this?
Palmitate acid, which is a stored form of energy
What are the stages of fatty acid synthesis?
- Elongation (acyl-malonyl ACP enzyme forms acetoacetyl-ACP)
- Reduction - dehydration - reduction (NADPH is used)
- Elongation cycle repeated 6 more times using malonyl coenzyme A until we reach palmityl-ACP
- A thioesterase cleaves palmityl coenzyme A from the ACP
What carrier molecule is used in the synthesis of fatty acid?
What is ACP?
Acyl carrier protein
What is the final reaction that produces palmitate?
Why is multifunctional fatty acid synthase such a large complex?
So that all the 7 enzymes required for the synthesis for fatty acid are next to each other in the cytosol
How much NADPH does the formation of palmitate use?
Where do the 14 NADPH used in the synthesis of fatty acid come from?
6 from pentose phosphate pathway
8 from malic enzymes that converts malate to pyruvate
What steps of the synthesis of fatty acid do you need NADPH for?
The growing of the chain
Where do any further modifications after the synthesis of palmitate occur?
In the mitochondria and endoplasmic reticulum
What are some further modifications of palmitate?
What is the fate of synthesised fatty acid?
Ends up being part of adipose tissue around the body
What is the carrier protein for the synthesis of fatty acid?
What is the carrier protein for the degradation of fatty acid?
What is the building block for the synthesis of fatty acids?
Malonyl coenzyme A
What is the building block for the degradation of fatty acids?
Acetyl coenzyme A
What is the redox for the syntheis of fatty acids?
What is the redox for the degradation of fatty acids?
What are the differences between the synthesis and degradation of fatty acids?
What are some specialised lipid classes?
What are steroid hormones?
Chemical substances that serve as chemical messengers
What is cholesterol?
Starting matieral for the synthesis of steroid hormone
What are eicosanoids?
Derived from 20 carbon unsaturated fatty acids and synthesised throughout the body
What kind of structure do steroids contain?
A ring system
What are the functions of cholesterol?
Component of cell membranes
Precurser of other substances (sterol hormones, vitamin D, bile acids)
Form bile salts
Where is cholesterol mainly synthesised and where is it found in the diet?
In the liver and in animal foods
How can cholesterol synthesis be regulated?
By inhibiting the rate limiting step,
HMG - CoA → Mevalonate
What are statins?
Drug that inhibits HMG-CoA reductase
What do statins do?
Lower cholesterol levels and decreases the risk of cardiovascular diseases
What are functions of eicosanoids?
Exert control over inflammatory or immunity
Messengers in the CNS
What can you say about the half life of eicosanoids?
They have a short half life
What are eicosanoids derived from?
Omega-3 or omega-6 fatty acids
What can eicosanoids regulate?
Pain and fever
What kind of drugs is asparin?
Nonsteroidal anti-inflammatory drugs (NSAIDs)
What do nonsteroidal anti-inflammatory drugs like asparin do?
Inhibit COX1 and COX2 enzymes which are anti-inflammatory and are fever reducing