Tutorial - Week 11 - Fatty acid metabolism

Question 1

Concepts:

1. Overview of fatty acids degradation (beta-oxidation)
2. Overview of fatty acid biosynthesis
3. Regulation of metabolism: tissues & hormones

Question 2

Fatty acids (FA) are…?

Answer 2

Question 3

T/F: Free fatty acids are uncommon, they normally exist as derivatives, known as
triacylglycerol

Answer 3

True

Question 4

What is Triacylglycerol

Answer 4

(TAG, triglyceride, or just fat): glycerol esterified with 3 fatty acids

Question 5

What is the function of TAGs?

Answer 5

TAGs are storage lipids and are stored in fat cells (adipocytes) as lipid droplets, in
adipose tissue

Question 6

What is the process of fatty acid catabolism?

Answer 6

Question 7

The use of FA as fuel requires ______ stages of processing:

What are those stages?

Answer 7

3

Question 8

Describe the process of Mobilisation of fatty acid catabolism (stage 1)

Answer 8

Question 9

Describe stage 2 of the fatty acid catabolism process - activation

Answer 9

Question 10

fatty acyl-CoA formed in the ___________
binds to _________ to be shuttled across to
the ________________

Answer 10

cytosol side

carnitine

inner mitochondrial membrane

Question 11

Once inside the matrix, the FA is transferred from ________ back to ____

Answer 11

carnitine

CoA

Question 12

Complete the equation

Answer 12

Question 13

Describe stage 3 of the fatty acid catabolism process (degradation - beta-oxidation)

Answer 13

Question 14

Degradation of fatty acids:

Each round of the ____ reactions shortens the acyl chain by ___ carbons, and
generates:…?

Answer 14

4

2

1 acetyl-CoA (2C), 1 NADH and 1 FADH

Question 15

FA β-oxidation is repeated until…?

Answer 15

the acyl chain is all converted into acetyl-CoA
molecules

Question 16

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 ____________________

Answer 16

7

β-oxidation

8 Acetyl-CoA, 7 NADH and 7 FADH

Question 17

T/F: Acetyl-CoA can be further oxidised in the TCA cycle

Answer 17

True

Question 18

The acetyl-CoA produced from the oxidation of fatty acids can be oxidised to…? By what? To obtain what?

Answer 18

to CO2 by the TCA cycle and can be used to obtain ATP via oxidative phosphorylation

Question 19

One molecule of Palmitoyl-CoA (C16) when fully oxidised to _____ generates ____ ATP

Answer 19

CO2

108

Question 20

Activation of Palmitoyl to Palmitoyl-CoA is equivalent to ___________

Therefore the net yield of ATP is?

Answer 20

2 ATP (ATP —> AMP)

106 ATP molecules

Question 21

Where does the biosynthesis of fatty acids occur? What is it initiated by?

Answer 21

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

Question 22

The malonyl group is covalently linked to the…?

Answer 22

Acyl carrier protein (ACP)

Question 23

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?

Answer 23

1. Condensation of acetyl group and malonyl
2. Reduction using NADPH as electron donor
3. Dehydration
4. Reduction using NADPH as electron donor

These reactions occur in the fatty acid synthase (a complex of enzymes with multiple active sites)

Question 24

Each round of the 4 reactions increases the acyl chain by ____ carbons and uses…?

Answer 24

2 carbons, and uses reduction power from
2 NADPH

Question 25

Biosynthesis of fatty acids is tightly regulated by what?

Answer 25

the activity of acetyl-CoA carboxylase

Question 26

To generate 1 palmitate fatty acid (_______), it requires _____ rounds of reactions, it uses…?

Answer 26

C16:0

7

14 NADPH

Question 27

Describe β-oxidation (6 main points)

1. what kind of process?
2. where does it occur?
3. What is the unit removed?
4. FA is activated by?
5. What does it use as electron acceptors?
6. Controlled by?

Answer 27

Question 28

Describe Biosynthesis (6 points)

1. What kind of process is it, meaning?
2. Where does it occur?
3. The unit added is?
4. When is it activated?
5. What does it use and is it as an electron donor or
   acceptor?
6. What is it controlled by?

Answer 28

Question 29

T/F: Each tissue/organ has a unique metabolic profile:

Answer 29

True

Question 30

What does the brain require and what does it use as it’s source of energy?

Answer 30

Brain requires permanent supply of energy and oxygen, and uses glucose as a source of energy

Question 31

Liver adapts to ____________ and can _______ as
required; can function in…?

Answer 31

changing demands

switch

the absence of O2 for some periods of time

Question 32

Adipose tissue _______ and ______ ______ as TAGs and releases them into the blood

Answer 32

stores

supplies fatty acids

Question 33

Describe the metabolism of skeletal muscle

Answer 33

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

Question 34

Heart muscle obtains most of ATP from…?

Answer 34

oxidative phosphorylation using FA as a fuel

Question 35

T/F: Control of metabolism can be via hormones, they control the synthesis of enzymes
involved in specific metabolic pathways

Answer 35

True

Question 36

Hormones can be chemically diverse:

List the peptides, cholesterol derivatives and tyrosine derivative

Answer 36

1. Insulin and Glucagon are peptides
2. Steroid hormones and Vitamin D are cholesterol derivatives
3. Adrenaline is a catecholamine (Tyrosine derivative)

Question 37

Hormones act on different receptors:

1. Insulin, Glucagon and Adrenaline bind to…?
2. Steroid hormones and Vitamin D enter cells and bind to…?

Answer 37

1. plasma membrane receptors
2. nuclear receptors
   to induce direct transcriptional regulation

Question 38

T/F: Insulin and glucagon are not often considered the major endocrine hormones

Answer 38

False - they are the major endocrine hormones

Question 39

Explain why insulin is the major anabolic endocrine hormone

Answer 39

Question 40

Explain why glucagon/adrenaline are the major catabolic endocrine hormones

Answer 40

Question 41

Key concept:

Overview of fatty acid catabolism:

1. How many stages does it have?
2. Mobilisation of fatty acids from TAG occurs in?
3. FAs are activated to…?
4. FAs β-oxidation repeats a sequence of ____ reactions and are…?

Answer 41

Question 42

Key concept:

Overview of fatty acid anabolism:

1. where does it occur?
2. What is it initiated by?
3. FA synthesis occurs through?
4. These 4 reactions occur in…?
5. Each round of the ____ reactions increases…?

Answer 42

Question 43

Key concept:

Regulation of metabolism: tissues & hormones

1. hormones control…?
2. Energy demands are tissue-_______
3. Insulin is the major…?
4. Glucagon is the major…?

Answer 43

Question 44

Do you know what the final exam will look like? What do you need to bring and should you read the questions very carefully?

Answer 44

Question 45

How should you prepare for the final?

Answer 45

Question 46

What have we learned in LQB381 Biochemistry?

Answer 46

Question 47

Sonia’s tips for the final

Answer 47

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:

1. read questions and options carefully!!
2. Choose the BEST answer, read them all
3. bring calc, not many calculations to be done at all
4. Only calculating things covered in tutorials or in theory (may not even need a calculator - no concentrations or beer-lambert law etc)
5. Tutorial slides have the most important concepts (most important put in tuts!)
6. Exam looking more at the second half of semester. -final revision session next week!