Tutorial - Week 11 - Fatty acid metabolism Flashcards
Concepts:
- Overview of fatty acids degradation (beta-oxidation)
- Overview of fatty acid biosynthesis
- Regulation of metabolism: tissues & hormones
Fatty acids (FA) are…?
T/F: Free fatty acids are uncommon, they normally exist as derivatives, known as
triacylglycerol
True
What is Triacylglycerol
(TAG, triglyceride, or just fat): glycerol esterified with 3 fatty acids
What is the function of TAGs?
TAGs are storage lipids and are stored in fat cells (adipocytes) as lipid droplets, in
adipose tissue
What is the process of fatty acid catabolism?
The use of FA as fuel requires ______ stages of processing:
What are those stages?
3
Describe the process of Mobilisation of fatty acid catabolism (stage 1)
Describe stage 2 of the fatty acid catabolism process - activation
fatty acyl-CoA formed in the ___________
binds to _________ to be shuttled across to
the ________________
cytosol side
carnitine
inner mitochondrial membrane
Once inside the matrix, the FA is transferred from ________ back to ____
carnitine
CoA
Complete the equation
Describe stage 3 of the fatty acid catabolism process (degradation - beta-oxidation)
Degradation of fatty acids:
Each round of the ____ reactions shortens the acyl chain by ___ carbons, and
generates:…?
4
2
1 acetyl-CoA (2C), 1 NADH and 1 FADH
FA β-oxidation is repeated until…?
the acyl chain is all converted into acetyl-CoA
molecules
FA β-oxidation is repeated until the acyl chain is all converted into acetyl-CoA
molecules:
- For example: Palmitoyl-CoA with 16 carbons, needs ___ rounds of _________ to
obtain ____________________
7
β-oxidation
8 Acetyl-CoA, 7 NADH and 7 FADH
T/F: Acetyl-CoA can be further oxidised in the TCA cycle
True
The acetyl-CoA produced from the oxidation of fatty acids can be oxidised to…? By what? To obtain what?
to CO2 by the TCA cycle and can be used to obtain ATP via oxidative phosphorylation
One molecule of Palmitoyl-CoA (C16) when fully oxidised to _____ generates ____ ATP
CO2
108
Activation of Palmitoyl to Palmitoyl-CoA is equivalent to ___________
Therefore the net yield of ATP is?
2 ATP (ATP —> AMP)
106 ATP molecules
Where does the biosynthesis of fatty acids occur? What is it initiated by?
In the cytoplasm
It is initiated by the formation of malonyl-CoA from acetyl-CoA, in a 3-steps reaction
catalysed by acetyl-CoA carboxylase
The malonyl group is covalently linked to the…?
Acyl carrier protein (ACP)
FA synthesis occurs through condensation of acetyl (units of 2 Carbons) onto malonyl, in a sequence of 4 reactions:
What are they?
Where do these reaction occur?
- Condensation of acetyl group and malonyl
- Reduction using NADPH as electron donor
- Dehydration
- Reduction using NADPH as electron donor
These reactions occur in the fatty acid synthase (a complex of enzymes with multiple active sites)
Each round of the 4 reactions increases the acyl chain by ____ carbons and uses…?
2 carbons, and uses reduction power from
2 NADPH
Biosynthesis of fatty acids is tightly regulated by what?
the activity of acetyl-CoA carboxylase
To generate 1 palmitate fatty acid (_______), it requires _____ rounds of reactions, it uses…?
C16:0
7
14 NADPH
Describe β-oxidation (6 main points)
- what kind of process?
- where does it occur?
- What is the unit removed?
- FA is activated by?
- What does it use as electron acceptors?
- Controlled by?
Describe Biosynthesis (6 points)
- What kind of process is it, meaning?
- Where does it occur?
- The unit added is?
- When is it activated?
- What does it use and is it as an electron donor or
acceptor? - What is it controlled by?
T/F: Each tissue/organ has a unique metabolic profile:
True
What does the brain require and what does it use as it’s source of energy?
Brain requires permanent supply of energy and oxygen, and uses glucose as a source of energy
Liver adapts to ____________ and can _______ as
required; can function in…?
changing demands
switch
the absence of O2 for some periods of time
Adipose tissue _______ and ______ ______ as TAGs and releases them into the blood
stores
supplies fatty acids
Describe the metabolism of skeletal muscle
Skeletal muscle is specialised to produce and use ATP for
mechanical work. When active, it uses glycogen as a source of glucose to obtain ATP via glycolysis and lactate
fermentation, or oxidative phosphorylation. At rest, it uses fatty acids as the preferred fuel
Heart muscle obtains most of ATP from…?
oxidative phosphorylation using FA as a fuel
T/F: Control of metabolism can be via hormones, they control the synthesis of enzymes
involved in specific metabolic pathways
True
Hormones can be chemically diverse:
List the peptides, cholesterol derivatives and tyrosine derivative
- Insulin and Glucagon are peptides
- Steroid hormones and Vitamin D are cholesterol derivatives
- Adrenaline is a catecholamine (Tyrosine derivative)
Hormones act on different receptors:
- Insulin, Glucagon and Adrenaline bind to…?
- Steroid hormones and Vitamin D enter cells and bind to…?
- plasma membrane receptors
- nuclear receptors
to induce direct transcriptional regulation
T/F: Insulin and glucagon are not often considered the major endocrine hormones
False - they are the major endocrine hormones
Explain why insulin is the major anabolic endocrine hormone
Explain why glucagon/adrenaline are the major catabolic endocrine hormones
Key concept:
Overview of fatty acid catabolism:
- How many stages does it have?
- Mobilisation of fatty acids from TAG occurs in?
- FAs are activated to…?
- FAs β-oxidation repeats a sequence of ____ reactions and are…?
Key concept:
Overview of fatty acid anabolism:
- where does it occur?
- What is it initiated by?
- FA synthesis occurs through?
- These 4 reactions occur in…?
- Each round of the ____ reactions increases…?
Key concept:
Regulation of metabolism: tissues & hormones
- hormones control…?
- Energy demands are tissue-_______
- Insulin is the major…?
- Glucagon is the major…?
Do you know what the final exam will look like? What do you need to bring and should you read the questions very carefully?
How should you prepare for the final?
What have we learned in LQB381 Biochemistry?
Sonia’s tips for the final
Each multichoice is worth 2% of the total 100% each
Learn the biomolecules
Short answer questions - 2 enzymes and 2 in metabolsim
How to do the best:
- read questions and options carefully!!
- Choose the BEST answer, read them all
- bring calc, not many calculations to be done at all
- Only calculating things covered in tutorials or in theory (may not even need a calculator - no concentrations or beer-lambert law etc)
- Tutorial slides have the most important concepts (most important put in tuts!)
- Exam looking more at the second half of semester. -final revision session next week!
