Lipids 3 Flashcards Preview

Science for Medicine > Lipids 3 > Flashcards

Flashcards in Lipids 3 Deck (56):
1

Where do we get fatty acids from?

Diet

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

2

Where does fatty acid synthesis happen?

Liver

Lactating mammary gland

Adipose tissue

3

What part of the cell does fatty acid synthesis happen?

Cytosol

4

Where is acetyl coenzyme formed?

Mitochondrial matrix

5

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

Fatty acid synthesis happens in the cytosol

6

Can acetyl coenzyme A cross the mitochondrial membrane?

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

7

How does acetyl cross the mitochondrial membrane?

By using the citrate shuttle

8

What is the process of the citrate shuttle?

  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

9

When does the citrate shuttle happen?

When citrate concentration in the mitochondria is high

10

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

NADPH

11

What enzymes are involved in fatty acid synthesis?

Acetyl coenzyme A carboxylase

Fatty acid synthase

12

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

Acts as an activator/regulator

13

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

Acts as a multifunctional enzyme

14

What does fatty acid synthesis need?

Acetyl coenzyme A

NADPH

15

What is the product of fatty acid synthesis?

Palmitic acid

16

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

Melanyl coenzyme A

17

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

Acetyl coenzyme A + ATP → malonyl coenzyme A

18

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

19

What hormone activates acetyl coenzyme A carboxylase?

Insulin

20

What hormone and neurotransmitter inhibits acetyl coenzyme A carboxylase?

Glucagon and noradrenaline

21

How many reactions are in the synthesis of fatty acid?

A lot, more than 7

22

What does fatty acid synthesis form and what is this?

Palmitate acid, which is a stored form of energy

23

What are the stages of fatty acid synthesis?

  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

24

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

NADPH

25

What is ACP?

Acyl carrier protein

26

What is the final reaction that produces palmitate?

27

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

28

How much NADPH does the formation of palmitate use?

14

29

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

30

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

The growing of the chain

31

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

In the mitochondria and endoplasmic reticulum

32

What are some further modifications of palmitate?

Unsaturation

Elongation

Branching

33

What is the fate of synthesised fatty acid?

Ends up being part of adipose tissue around the body

34

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

ACP

35

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

Coenzyme A

36

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

Malonyl coenzyme A

37

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

Acetyl coenzyme A

38

What is the redox for the syntheis of fatty acids?

Reductant NADP+

39

What is the redox for the degradation of fatty acids?

Oxidant NAD+/FAD2+

40

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

41

What are some specialised lipid classes?

Steroid hormones

Cholesterol

Eicosanoids

42

What are steroid hormones?

Chemical substances that serve as chemical messengers

43

What is cholesterol?

Starting matieral for the synthesis of steroid hormone

44

What are eicosanoids?

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

45

What kind of structure do steroids contain?

A ring system

46

What are the functions of cholesterol?

Component of cell membranes

Precurser of other substances (sterol hormones, vitamin D, bile acids)

Form bile salts

47

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

In the liver and in animal foods

48

How can cholesterol synthesis be regulated?

By inhibiting the rate limiting step, 

HMG - CoA → Mevalonate

49

What are statins?

Drug that inhibits HMG-CoA reductase

50

What do statins do?

Lower cholesterol levels and decreases the risk of cardiovascular diseases

51

What are functions of eicosanoids?

Signalling molecules

Exert control over inflammatory or immunity

Messengers in the CNS

52

What can you say about the half life of eicosanoids?

They have a short half life

53

What are eicosanoids derived from?

Omega-3 or omega-6 fatty acids

54

What can eicosanoids regulate?

Inflammatory response

Pain and fever

Blood pressure

Blood clotting

Reproductive function

Sleep/wake cycle

55

What kind of drugs is asparin?

Nonsteroidal anti-inflammatory drugs (NSAIDs)

56

What do nonsteroidal anti-inflammatory drugs like asparin do?

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