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01. Year 1: Science for Medicine > Lipids 3 > Flashcards

Lipids 3 Flashcards

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1
Q

Where do we get fatty acids from?

A

Diet

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

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2
Q

Where does fatty acid synthesis happen?

A

Liver

Lactating mammary gland

Adipose tissue

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3
Q

What part of the cell does fatty acid synthesis happen?

A

Cytosol

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4
Q

Where is acetyl coenzyme formed?

A

Mitochondrial matrix

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5
Q

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

A

Fatty acid synthesis happens in the cytosol

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6
Q

Can acetyl coenzyme A cross the mitochondrial membrane?

A

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

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7
Q

How does acetyl cross the mitochondrial membrane?

A

By using the citrate shuttle

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8
Q

What is the process of the citrate shuttle?

A
  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
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9
Q

When does the citrate shuttle happen?

A

When citrate concentration in the mitochondria is high

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10
Q

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

A

NADPH

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11
Q

What enzymes are involved in fatty acid synthesis?

A

Acetyl coenzyme A carboxylase

Fatty acid synthase

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12
Q

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

A

Acts as an activator/regulator

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13
Q

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

A

Acts as a multifunctional enzyme

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14
Q

What does fatty acid synthesis need?

A

Acetyl coenzyme A

NADPH

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15
Q

What is the product of fatty acid synthesis?

A

Palmitic acid

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16
Q

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

A

Melanyl coenzyme A

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17
Q

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

A

Acetyl coenzyme A + ATP → malonyl coenzyme A

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18
Q

How is acetyl coenzyme A carboxylase regulated?

A

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

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

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19
Q

What hormone activates acetyl coenzyme A carboxylase?

A

Insulin

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20
Q

What hormone and neurotransmitter inhibits acetyl coenzyme A carboxylase?

A

Glucagon and noradrenaline

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21
Q

How many reactions are in the synthesis of fatty acid?

A

A lot, more than 7

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22
Q

What does fatty acid synthesis form and what is this?

A

Palmitate acid, which is a stored form of energy

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23
Q

What are the stages of fatty acid synthesis?

A
  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
Q

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

A

NADPH

25
Q

What is ACP?

A

Acyl carrier protein

26
Q

What is the final reaction that produces palmitate?

A
27
Q

Why is multifunctional fatty acid synthase such a large complex?

A

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

28
Q

How much NADPH does the formation of palmitate use?

A

14

29
Q

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

A

6 from pentose phosphate pathway

8 from malic enzymes that converts malate to pyruvate

30
Q

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

A

The growing of the chain

31
Q

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

A

In the mitochondria and endoplasmic reticulum

32
Q

What are some further modifications of palmitate?

A

Unsaturation

Elongation

Branching

33
Q

What is the fate of synthesised fatty acid?

A

Ends up being part of adipose tissue around the body

34
Q

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

A

ACP

35
Q

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

A

Coenzyme A

36
Q

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

A

Malonyl coenzyme A

37
Q

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

A

Acetyl coenzyme A

38
Q

What is the redox for the syntheis of fatty acids?

A

Reductant NADP+

39
Q

What is the redox for the degradation of fatty acids?

A

Oxidant NAD+/FAD2+

40
Q

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

A
41
Q

What are some specialised lipid classes?

A

Steroid hormones

Cholesterol

Eicosanoids

42
Q

What are steroid hormones?

A

Chemical substances that serve as chemical messengers

43
Q

What is cholesterol?

A

Starting matieral for the synthesis of steroid hormone

44
Q

What are eicosanoids?

A

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

45
Q

What kind of structure do steroids contain?

A

A ring system

46
Q

What are the functions of cholesterol?

A

Component of cell membranes

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

Form bile salts

47
Q

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

A

In the liver and in animal foods

48
Q

How can cholesterol synthesis be regulated?

A

By inhibiting the rate limiting step,

HMG - CoA → Mevalonate

49
Q

What are statins?

A

Drug that inhibits HMG-CoA reductase

50
Q

What do statins do?

A

Lower cholesterol levels and decreases the risk of cardiovascular diseases

51
Q

What are functions of eicosanoids?

A

Signalling molecules

Exert control over inflammatory or immunity

Messengers in the CNS

52
Q

What can you say about the half life of eicosanoids?

A

They have a short half life

53
Q

What are eicosanoids derived from?

A

Omega-3 or omega-6 fatty acids

54
Q

What can eicosanoids regulate?

A

Inflammatory response

Pain and fever

Blood pressure

Blood clotting

Reproductive function

Sleep/wake cycle

55
Q

What kind of drugs is asparin?

A

Nonsteroidal anti-inflammatory drugs (NSAIDs)

56
Q

What do nonsteroidal anti-inflammatory drugs like asparin do?

A

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

01. Year 1: Science for Medicine (55 decks)

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