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Nutrition and Metabolism > Fats > Flashcards

Fats Flashcards

1
Q

What is the Greek word for lipid?

A

lipos (fat)

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2
Q

What is a lipid?

A

biomolecules that partition into organic as opposed to aqueous solution

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3
Q

What are lipids involved in?

A
  • energy storage
  • cell structure
  • signal transduction
  • intracellular transport
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4
Q

What falls under the lipids category?

A
  • dietary oils and fats
  • cholesterol
  • hormones
  • inflammatory mediators
  • vitamins
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5
Q

How many genes are in lipid metabolism alone?

A

1116 genes

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6
Q

How many estimated genes involved in lipid binding proteins are there?

A

1000 genes

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7
Q

What are lipids major importance for?

A

cell function and structure

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8
Q

How many families of lipids are there?

A

8

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9
Q

How many lipid families does the human plasma contain?

A

6

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10
Q

How many structurally different lipids are in the human plasma?

A

588

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11
Q

What does the double bond introduce into the carbon structure?

A

kinks

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12
Q

What does the lipid structure contain?

A
  1. carboxylic acid group - acid = H+ donor
  2. Forms reversible ester bonds with -OH groups (e.g. glycerol)
  3. Forms thioester bonds with -SH (sulphydryl) groups (e.g. CoA)
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13
Q

What are the 8 classes of lipids?

A
  1. fatty acyls
  2. glycerolipids
  3. glycerophospholipids
  4. sterol lipids
  5. sphingolipids
  6. saccharolipids
  7. prenol lipids
  8. polyketides
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14
Q

Give an example of saturated fatty acid:

A
  • stearic acid

- octadecanoic acid

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15
Q

Give an example of monosaturated fatty acid:

A
  • oleic acid

- 9Z-octadecenoic acid

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16
Q

Give an example of polysaturated (PUFA) fatty acid:

A

arachidonic acid

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17
Q

Give an example of essential fatty acid:

A
  • alpha-linolenic acid

- gamma-linolenic acid

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18
Q

What are essential fatty acids?

A
  • not produced by body

- used to produce eicosanoids and endocannabinoids

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19
Q

what are eicosanoids used for?

A
  • inflammation

- control of vasodilation (BP)

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20
Q

What is the structure of a glycerolipid made of?

A
  • free fatty acid
  • glycerol
  • ester bond
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21
Q

What are glycerolipids involved in and its properties?

A
  • energy storage
  • lipid synthesis via photosynthesis - carbohydrates
  • physical properties, determined by saturation
  • of acyl chains
  • viscous with melting point
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22
Q

Since fatty acid is a carbon fuel source, how kJ is in palmitic acid?

A

19.46 kJ/LO2

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23
Q

What are the type of lipases releasing fatty acids and what are the functions if any?

A
  1. Pancreatic lipase - fatty acids for transport into gut lining cells (enterocytes)
  2. Hormone sensitive lipase - fatty acid in adipocytes, turned on by PKA
  3. Lipoprotein lipase
  4. Lysosomal lipase - in lysosome hydrolyses cholesterol esters and triacylglycerols delivered on LDLs
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24
Q

Where is serum albumin made and what is it?

A
  • made in liver
  • most abundant protein in blood
  • carrier protein for fatty acids and others
  • deliver fstty acids to/from adipocytes and skeletal muscles
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25
Q

how much serum albumin is there in blood?

A

35-50g/l

26
Q

How are triglycerides carried around the body?

A

in complex with proteins lipoprotein particles (e.g. VLDL)

27
Q

How can fatty acids enter cells?

A

have charged carboxylic acid groups and enter cells via channel protein (e.g. CD36)

28
Q

How do you activate hormone sensitive lipase?

A
  • adrenaline

- glucagon (liver, kidney)

29
Q

When there’s not enough glucose, what happens to fatty acids?

A

ß-oxidation of fatty acids for energy release, you get acetyl-coA

30
Q

What 3 areas does acetyl-coA contribute to?

A
  • cholesterol synthesis
  • fatty acid synthesis, lipogenesis
  • Krebs (TCA) cycle - ATP energy production
31
Q

Where does the fatty acid activation by coA addition take place at?

A

in the cytoplasm

32
Q

What catalyses the fatty acid activation by coA addition?

A

acyl-coA synthetase long chain enzymes (ACSL)

33
Q

How do you move acyl-coA into the mito. matrix?

A

the coA is swapped with molecule of carnitine

34
Q

How many enzymatic reactions of ß-oxidation are there?

A

4

35
Q

What is mitochondrial trifunctional protein (MTP)?

A

aka TFP, heterotrimer localised to the inner mitochondrial membrane and catalyses 3 out of 4 steps in ß-oxidation

36
Q

What is the structure of mitochondrial trifunctional protein (MTP)?

A

4 alpha subunits, 4 ß subunits

37
Q

The activation with coA and carnitine transfer only applied to?

A

long-chain fatty acids C12-C20, medium C8-C10 and short chain fatty acids can enter the mito. directlky for ß-oxidation

38
Q

In the ß-oxidation sequence, what do unsaturated fatty acids tend to have?

A

cis double bonds that have to be made trans to enter 2nd step in the oxidation

39
Q

What does the close contact of peroxisomes and mitochondria do?

A

facilitates transfer of substrates to mitochondria

40
Q

Where are FFA receptors found and what does their signalling do?

A

on pancreatic cells, signalling cascade leads to insulin secretion

41
Q

What is peroxisome proliferator-activated receptor γ (PPARγ)?

A
  • nuclear transcription factor that binds and is activated by arachidonic acid.
  • binds DNA at specific PPRE elements
42
Q

What is protein acylation?

A
  • post-translational modification of proteins
  • covalent addition of lipid to a protein
  • most common is addition of palmitic acid to cysteine SH groups on protein
  • termed = s-palmitoylation
43
Q

Describe insulin:

A
  • signalling molecule, binds to surface receptors
  • peptide hormone produced in pancreas
  • increases glucose transport into cells
  • inhibits activation of hormone sensitive lipase
  • acetyl coA from glucose available for fatty acid (lipogenesis) and cholesterol synthesis
44
Q

Why is lipogenesis upregulated in cancer?

A

lipids needed for cell membranes (proliferation) and signalling phospholipids (proliferation, survival, motility)

45
Q

How many times does the cycle reiterate to generate 16C fatty acid palmitate?

A

6 times

46
Q

In the involvement of ATP citrate lyase (ACLY), how is the citrate first transported out of the mitochondria?

A

by citrate transporter protein (CTP1)

47
Q

What is acetyl-coA carboxylase?

A

key enzyme that converts acetyl-coA into malonyl-coA

  • CO2 released later
  • biotin is a co-factor
  • committed step in FA synthesis
48
Q

What are the 2 isoforms of ACC (acetyl-coA carboxylase)?

A

ACC1 and ACC2

49
Q

What is the function of ACC1?

A
  • lipogenic tissue

- generates malonyl coA for fatty acid synthesis

50
Q

What is the function of ACC2?

A
  • cardiac, muscle tissue

- generates malonyl coA at mitochondria outer membrane

51
Q

What does malonyl coA inhibit?

A

carnitine palmitoyltransferase 1

52
Q

Which hormones stimulate ß-oxidation to activate AMP-activated protein kinase to induce phosphorylation and inhibition?

A
  • adrenaline
  • noradrenaline
  • glucagon
53
Q

In the regulation of acetyl CoA carboxylase, what is protein phosphatase 2 activated by, and what happens as a result?

A
  • insulin receptor activates it
  • dephosphorylates the enzyme
  • activation leads to more lipogenesis
54
Q

What is FA synthase enzyme?

A
  • enzyme complex
  • excludes acetyl-coA carboxylase
  • exists as dimer of two complete, anti-parallel complexes
  • cytosolic
55
Q

Which step in FA synthesis iterates many times to grow the FA backbone?

A

step 2, the setting up of malonyl-ACP

56
Q

What is b-ketoacyl-ACP?

A
  • its a condensing enzyme

- part of FA synthase complex

57
Q

In FA synthesis, what is used to reduce the ß-carbonyl to hydroxyl group?

A

NADPH

58
Q

What cleaves the ACP from palmitoyl-ACP?

A

thioesterase

59
Q

Give the summarised steps of FA synthesis:

A
  1. Set up malonyl-ACP
  2. Condense them, giving acetoacetyl-ACP and CO2
  3. Use NADPH to reduce ß-carbonyl to hydroxyl group
  4. Remove the hydroxyl group as H2O leaving a double bond
  5. Use another NADPH to reduce the double bond
  6. Repeat step 1 using the new 4-carbon butyryl-ACP in place of acetyl-ACP
  7. Thioesterase cleaves ACP from palmitoyl-ACP, releasing palmitate
60
Q

Where do elogations by elongase enzymes take place at?

A

endoplasmic reticulum

Nutrition and Metabolism (14 decks)

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