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Semester 2-MEH > Session 2-Energy Production:Lipids > Flashcards

Session 2-Energy Production:Lipids Flashcards

1
Q

True or false: lipids are generally soluble in water

A

FALSE - insoluble

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2
Q

Lipids are more reduced than carbs. What are the consequences of this?

A

Lipids release more energy when oxidised

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3
Q

What are the three classes of lipids?

A

1) Fatty acid (FA) derivatives
2) Hydroxy-methyl-glutaric (HMG) acid derivatives
3) Vitamins

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4
Q

Which vitamins are lipid molecules?

A

A, D, E and K

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5
Q

Which fatty acid derivatives do we need to know?

A

Fatty acids

Triacylglycerols (triglycerides)

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6
Q

What are FA stored as?

A

Triacylglycerols

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7
Q

Which HMG acid derivative do we need to know?

A

Ketone bodies (C4)

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8
Q

What are ketone bodies?

A

Water soluble fuel molecules-alternative substrate when glucose is low, solubilise energy in fat

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9
Q

Which process produces triacylglycerols (TAG)?

A

Esterification

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10
Q

True or false: triacylglycerols (TAG) are hydrophilic

A

FALSE - hydrophobic

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11
Q

How are triacylglycerols (TAG) stored within cells?

A

Lipid droplets

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12
Q

When are TAGs utilised?

A

Prolonged exercise
‘Starvation’
During pregnancy

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13
Q

How is the storage/mobilisation of TAGs controlled by hormones?

A

Glucagon mobilises fat

Insulin puts fat into store

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14
Q

What are chylomicrons?

A

Lipoproteins formed to package FA and allow them to be transported in the blood

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15
Q

Which enzyme catalyses the breakdown of lipids in the small intestine?

A

Pancreatic lipase

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16
Q

How are FA carried to tissues?

A

Albumin-FA complex

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17
Q

Complete the sentence:

FA can be saturated, ___________ or _____________

A

Unsaturated

Amphipathic

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18
Q

Why are some polyunsaturated FA essential?

A

Because mammals cannot introduce a double bond beyond C9

19
Q

Where does triacylglycerol metabolism occur?

A

GI tract, extracellular

20
Q

Where does FA metabolism occur?

A

Mitochondria

21
Q

What activates FA outside the mitochondrion?

A

Linking to coenzyme A by the action of fatty acyl CoA synthase

22
Q

How are FA transported across the inner mitochondrial membrane?

A

Carnitine shuttle

23
Q

How many carbons are removed with each cycle of FA catabolism?

A

2

24
Q

What inhibits the transport of fatty acyl-CoA across the mitochondrial membrane?

A

Malonyl-CoA

25
Q

What is another term for FA catabolism?

A

Beta-oxidation

26
Q

How many ATP molecules are produced from C6 FA?

A

41

27
Q

Why doesn’t FA metabolism occur in the brain?

A

FA cannot pass through the blood/brain barrier

28
Q

Why doesn’t FA metabolism occur in RBCs?

A

No mitochondria

29
Q

Where is glycerol metabolised?

A

Liver

30
Q

What is the main convergence point for catabolic pathways?

A

Acetyl CoA

31
Q

Which vitamin does CoA contain?

A

B5

32
Q

Which atom links CH3CO group to coenzyme A?

A

S-atom

33
Q

True or false: ketone bodies are more hydrophilic than lipid

A

TRUE

34
Q

Which three ketone bodies are produced in the body?

A

1) Acetoacetate
2) Acetone
3) beta-hydroxybutyrate

35
Q

True or false: acetone is produced by the spontaneous decarboxylation of acetoacetate

A

TRUE

36
Q

What is the normal plasma ketone body concentration?

A

<1mM

37
Q

What is the plasma ketone body concentration in untreated type 1 diabetes?

A

> 10mM

38
Q

What synthesises ketone bodies?

A

Liver mitochondria

39
Q

What ensures that acetyl-CoA doesn’t enter the TCA cycle and instead forms ketone bodies?

A

NADH-high energy signal which inhibits the enzymes in the TCA cycle so acetyl-CoA doesn’t enter the TCA cycle

40
Q

Complete the sentence:

When the insulin/glucagon ratio is high (ie fed state), _______ is inhibited, _____________ is activated and this leads to the synthesis of cholesterol

A

Lyase

Reductase

41
Q

Complete the sentence:

When the insulin/glucagon ratio is low (ie starvation, diabetes), ______ is activated, ___________ is inhibited, leading to the synthesis of ________ _________

A

Lyase
Reductase
Ketone bodies

42
Q

What is ketonuria?

A

Excretion of large amounts of ketone bodies in the urine

43
Q

What can ketonuria be a test for?

A

Diabetes

44
Q

Volatile acetone may be excreted via which organ?

A

Lungs

Semester 2-MEH (21 decks)

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