Lipids 3

Question 1

Where do we get fatty acids from?

Answer 1

Diet

Synthesis (from excess carbohydrates and protein components, acetyl coenzyme A)

Question 2

Where does fatty acid synthesis happen?

Answer 2

Liver

Lactating mammary gland

Adipose tissue

Question 3

What part of the cell does fatty acid synthesis happen?

Answer 3

Cytosol

Question 4

Where is acetyl coenzyme formed?

Answer 4

Mitochondrial matrix

Question 5

Why does acetyl conezyme A need to be transfered from the mitochondrial matrix for fatty acid synthesis?

Answer 5

Fatty acid synthesis happens in the cytosol

Question 6

Can acetyl coenzyme A cross the mitochondrial membrane?

Answer 6

No, only the acetyl part can cross by using the citrate shuttle

Question 7

How does acetyl cross the mitochondrial membrane?

Answer 7

By using the citrate shuttle

Question 8

What is the process of the citrate shuttle?

Answer 8

1. Acetyl coenzyme A reacts with oxaloacetate to become citrate which crosses the membrane
2. In the cytosol citrate becomes is broken down into oxaloacetate and acetyl coenzyme A is released
3. Oxaloacetate uses NADH to become malate
4. Malate uses NADP⁺ to become pyruvate which crosses into the mitochondria membrane
5. Pyruvate is converted into oxaloacetate to be used again

Question 9

When does the citrate shuttle happen?

Answer 9

When citrate concentration in the mitochondria is high

Question 10

What is made during the citrate shuttle that is later used in the synthesis of fatty acids?

Answer 10

NADPH

Question 11

What enzymes are involved in fatty acid synthesis?

Answer 11

Acetyl coenzyme A carboxylase

Fatty acid synthase

Question 12

What does acetyl coenzyme A carboxylase do in the synthesis of fatty acids?

Answer 12

Acts as an activator/regulator

Question 13

What does fatty acid synthase do in the synthesis of fatty acids?

Answer 13

Acts as a multifunctional enzyme

Question 14

What does fatty acid synthesis need?

Answer 14

Acetyl coenzyme A

NADPH

Question 15

What is the product of fatty acid synthesis?

Answer 15

Palmitic acid

Question 16

What is acetyl coenzyme A carboxylase needed for the formation of?

Answer 16

Melanyl coenzyme A

Question 17

What is both the rate determining and commited step in fatty acid synthesis?

Answer 17

Acetyl coenzyme A + ATP → malonyl coenzyme A

Question 18

How is acetyl coenzyme A carboxylase regulated?

Answer 18

Activated by insulin (signal enough glucose so make fatty acid), insulin

Inhibited by palmitoyl coenzyme A (enough fatty acid) glucagon, noradrenaline

Question 19

What hormone activates acetyl coenzyme A carboxylase?

Answer 19

Insulin

Question 20

What hormone and neurotransmitter inhibits acetyl coenzyme A carboxylase?

Answer 20

Glucagon and noradrenaline

Question 21

How many reactions are in the synthesis of fatty acid?

Answer 21

A lot, more than 7

Question 22

What does fatty acid synthesis form and what is this?

Answer 22

Palmitate acid, which is a stored form of energy

Question 23

What are the stages of fatty acid synthesis?

Answer 23

1. Elongation (acyl-malonyl ACP enzyme forms acetoacetyl-ACP)
2. Reduction - dehydration - reduction (NADPH is used)
3. Elongation cycle repeated 6 more times using malonyl coenzyme A until we reach palmityl-ACP
4. A thioesterase cleaves palmityl coenzyme A from the ACP

Question 24

What carrier molecule is used in the synthesis of fatty acid?

Answer 24

NADPH

Question 25

What is ACP?

Answer 25

Acyl carrier protein

Question 26

What is the final reaction that produces palmitate?

Question 27

Why is multifunctional fatty acid synthase such a large complex?

Answer 27

So that all the 7 enzymes required for the synthesis for fatty acid are next to each other in the cytosol

Question 28

How much NADPH does the formation of palmitate use?

Answer 28

14

Question 29

Where do the 14 NADPH used in the synthesis of fatty acid come from?

Answer 29

6 from pentose phosphate pathway 8 from malic enzymes that converts malate to pyruvate

Question 30

What steps of the synthesis of fatty acid do you need NADPH for?

Answer 30

The growing of the chain

Question 31

Where do any further modifications after the synthesis of palmitate occur?

Answer 31

In the mitochondria and endoplasmic reticulum

Question 32

What are some further modifications of palmitate?

Answer 32

Unsaturation Elongation Branching

Question 33

What is the fate of synthesised fatty acid?

Answer 33

Ends up being part of adipose tissue around the body

Question 34

What is the carrier protein for the synthesis of fatty acid?

Answer 34

ACP

Question 35

What is the carrier protein for the degradation of fatty acid?

Answer 35

Coenzyme A

Question 36

What is the building block for the synthesis of fatty acids?

Answer 36

Malonyl coenzyme A

Question 37

What is the building block for the degradation of fatty acids?

Answer 37

Acetyl coenzyme A

Question 38

What is the redox for the syntheis of fatty acids?

Answer 38

Reductant NADP⁺

Question 39

What is the redox for the degradation of fatty acids?

Answer 39

Oxidant NAD⁺/FAD²⁺

Question 40

What are the differences between the synthesis and degradation of fatty acids?

Question 41

What are some specialised lipid classes?

Answer 41

Steroid hormones Cholesterol Eicosanoids

Question 42

What are steroid hormones?

Answer 42

Chemical substances that serve as chemical messengers

Question 43

What is cholesterol?

Answer 43

Starting matieral for the synthesis of steroid hormone

Question 44

What are eicosanoids?

Answer 44

Derived from 20 carbon unsaturated fatty acids and synthesised throughout the body

Question 45

What kind of structure do steroids contain?

Answer 45

A ring system

Question 46

What are the functions of cholesterol?

Answer 46

Component of cell membranes Precurser of other substances (sterol hormones, vitamin D, bile acids) Form bile salts

Question 47

Where is cholesterol mainly synthesised and where is it found in the diet?

Answer 47

In the liver and in animal foods

Question 48

How can cholesterol synthesis be regulated?

Answer 48

By inhibiting the rate limiting step, HMG - CoA → Mevalonate

Question 49

What are statins?

Answer 49

Drug that inhibits HMG-CoA reductase

Question 50

What do statins do?

Answer 50

Lower cholesterol levels and decreases the risk of cardiovascular diseases

Question 51

What are functions of eicosanoids?

Answer 51

Signalling molecules Exert control over inflammatory or immunity Messengers in the CNS

Question 52

What can you say about the half life of eicosanoids?

Answer 52

They have a short half life

Question 53

What are eicosanoids derived from?

Answer 53

Omega-3 or omega-6 fatty acids

Question 54

What can eicosanoids regulate?

Answer 54

Inflammatory response Pain and fever Blood pressure Blood clotting Reproductive function Sleep/wake cycle

Question 55

What kind of drugs is asparin?

Answer 55

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Question 56

What do nonsteroidal anti-inflammatory drugs like asparin do?

Answer 56

Inhibit COX1 and COX2 enzymes which are anti-inflammatory and are fever reducing