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Y1 Science For Medicine > Lipids 3 > Flashcards

Lipids 3 Flashcards

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1
Q

What are fatty acids synthesised from?

A

Acetyl CoA - a derivative of carbohydrate and protein. using ATP and NADPH.

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2
Q

Where is acetyl CoA and Fatty acid synthesised?

A

Acetyl Coa synthsised in the mitochondria and the Fatty Acid in the cytosol.

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3
Q

How is Acetyl CoA transported form the mitochondria to the cytosol for fatty acid synthesis?

A

The citrate shuttle

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4
Q

What compounds move in and out of the mitochondria during the citrate shuttle?

A

Citrate moves out carrying acetyl CoA

Pyruvate moves back in

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5
Q

What are the 2 reactions of the citrate shuttle within the mitochondria and their enzymes?

A

Pyruvate -> oxaloacetate (pyruvate carboxylase)

Oxaloacetate + Acetyl CoA -> Citrate (Citrate synthase)

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6
Q

What are the 3 main reactions of the citrate shuttle in the cytosol and their enzymes>?

A

Citrate -> oxaloacetate + Acetyle-CoA (Citrate Lyase)
Oxaloacetate + NADH -> Malate (Malate dehydrogenase)
Malate -> Pyruvate + NADPH (malate enzyme)

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7
Q

When does the citrate shuttle occur?

A

When citrate concentration in the mitochondria is high.

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8
Q

What is the first committed step of Fatty acid synthesis?

A

Acetyl CoA + HCO3 + ATP -> Malonyl-CoA +ADP + Pi + H+ (Acetyl-CoA carboxylase)

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9
Q

What Stimulates Acetyl-Coa Carboxylase?

A

Citrate signals thers enough glucose so Acetyl-CoA should be stored as FA.
Insulin

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10
Q

What deactivates Acetyl-CoA carboxylase?

A

Palmitoyl CoA signals theres enouh FA so halt synthesis
Glucagon
Epinephrine

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11
Q

What two groups are condensed in the first stage of FA synthesis?

A

Activated Acyl Group and Activated Malonyl group.

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12
Q

What are the 4 reactions from acyl and malonyl groups to an acyl group 2 carbons longer? (one cycle of FA synthesis)

A

Condensation
Reduction
Dehydration
Reduction

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13
Q

what is the overall equation for the first cycle of FA synthesis?

A

2 Acetyl CoA + 2 NADPH + 2 H+ + 1 ATP -> Acyl group (2 carbons longer) + 2 NADP + ADP + Pi + H2O.

(Every cycle after the first only used one acetyl CoA to make malonyl-CoA and the extended Acyl group from the last cycle)

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14
Q

What carrier protein is used in FA synthesis?

A

ACP (Acyl Carrier Protein)

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15
Q

What happens when a synthesised FA reaches its desired length?

A

The FA (Palmityl-CoA) is cleaved from the carrier protein ACP by a thioesterase.

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16
Q

What enzyme is used in most of FA synthesis?

A

Multifunctional Fatty Acid Synthase

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17
Q

What electron acceptor is used in FA synthesis?

A

NADP+ (NADPH)

18
Q

How much NADPH is needed for FA synthesis and where does it come from?

A

14 NADPH molecules are needed to produce a molecule of Palmityl-CoA.
8 come from the malate -> Pyruvate reaction in the citrate shuttle
6 comes from the Pentose Phosphate Pathway (PPP)

19
Q

What FA is produced in basic FA synthesis?

A

Palmityl-CoA (16C)

20
Q

Where does further modification of teh Palmityl-CoA occur?

A

Mitochondria and ER

21
Q

What is FA used for if not energy?

A

Storage as adipose tissue?

22
Q

How does FA become Adipose tissue?

A

FATTY ACID + glycerol -> TAG + protein + phospholipid + cholesterol -> VLDL -> ADIPOSE TISSUE.

23
Q

Where do FA synthesis and Degradation occure?

A

Synthesis occurs in the cytosol and degradation in the mitochondrial matrix

24
Q

What carier protein is involved in synthesis and which in deggradation?

A

ACP (Acyl carrier protein) is used in synthesis while CoA is used in Degradation

25
Q

Do FA synthesis/degradation use one or multiple enzymes?

A

Synthesis uses just one multi-functional enzyme (Fatty acid synthase) while degradation uses multiple enzymes

26
Q

What redox carriers are used in FA synthesis/Degradation and are they reducing or oxidising?

A

In synthesis NADP is used and is reducing

In degradation NAD and FAD are used and are oxidising

27
Q

What is the basic building block of synthesis and degradation?

A

Synthesis starts with malonyl CoA and degradation with Acetyl CoA.

28
Q

Name 3 specialised classes of lipids:

A

Steroid hormones
Cholesterol
Eicanosoids

29
Q

What are steroid hormones?

A

Chemical messengers in the body including sex hormones

30
Q

What is cholesterol used for?

A

The starting material for synthesis of steroid hormones.
A precurser to bile acids and vitamin D.
Membranes in the cell.

31
Q

What are eicanosoids derived from?

A

20C unsaturated fatty acids (eicasanoic acids).

32
Q

Where do we get cholesterol from?

A

Dietary from animal based food and synthesis in the liver.

33
Q

From what is cholesterol derived?

A

Acetyl CoA

34
Q

What enzyme is targeted when inhibiting the Acetyl-CoA -> Cholesterol pathway?

A

HMG-CoA Reductase

35
Q

What drug inhibits what enzymes in the Acetyl-CoA -> Cholesterol synthesis pathway?

A

Statins are used to inhibit HMG-CoA reductase

36
Q

What effect do statins have on the body?

A

They lower LDL levels by reducing chlesterol synthesis thus reducing risk of cardiovascular disease.

37
Q

From what FA are eicosanoids derived?

A

Omega-3 and Omega-6 FA>

38
Q

What can eicosanoid analogues used for?

A

Asthma treatment (leukotriene antagonists) and inducing labour (Prostoglandin analogues) etc.

39
Q

What 6 things do eicosanoid derivatives regulate?

A 
Blood pressure (prostacyclin)
Blood clotting (thromboxanes)
Menstrual cramps & reproductive fucntions (e.g. induction of labour.) [Prostaglandins]
Sleep/wake cycle
Pain/Fever (prostaglandins)
Inflammatory response
40
Q

What are eicosanoids precursers for?

A

Prostaglandins
Thromboxanes
Leukotrienes

Y1 Science For Medicine (35 decks)

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