Lipids Flashcards

1
Q

What are some properties of lipids

A

Heterogeneous organic molecules
Hydrophobic
Exist in cell membranes, as lipid droplets in adipose tissue, as lipoproteins in blood

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2
Q

What is the biological function of lipids

A
Stored form of energy
Structural element of membranes
Enzyme cofactors
Hormones
Vitamins A D E K
Signalling molecules
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3
Q

Lipid classes

A
Fatty acids
Triacylglycerol (TAG)
Phospholipids
Glycolipids
Steroids
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4
Q

What are the two types of fatty acids and what is the difference between them

A

Unsaturated - one or more double bond that kink hydrocarbon chain
Saturated - solid with no double bonds

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5
Q

Which fatty acids are essential

A

Linoleic and alpha linolenic

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6
Q

Where do you get essential fatty acids from

A

Plants

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7
Q

What are some ‘good fats’ and what makes them so

A

Vegetable oil e.g. olive or sunflower

They’re high in polyunsaturated fatty acids

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8
Q

What are some ‘bad fats’ and why

A

Stearic (beef)

High in saturated fatty acids

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9
Q

What is a ‘really bad fat’ and why is it so

A

Trans fatty acids, result from hydrogenation of vegetable oils e.g. man made hard margarine

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10
Q

After which point can humans not introduce double bones

A

Carbon 9

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11
Q

What are omega 3 fatty acids derived from

A

Linolenic acid

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12
Q

What does omega 3 FA do

A

Lowers plasma cholesterol, prevents atherosclerosis, lowers TAG, prevents obesity, reduces inflammation

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13
Q

Classis symptoms of essential fatty acid deficiency

A
Growth retardation
Reproductive failure
Skin lesions
Kidney and liver disorders
Subtle neurological and visual problems
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14
Q

What are triacylglycerols

A

Esters of fatty acids and glycerol

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15
Q

Function of triacylglycerols

A

Dietary fuel
Insulation
Water insoluble TAG coalesce into lipid droplets in adipose tissue
Major lipid component of adipose tissue

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16
Q

What are phospholipids composed of

A

Glycerol bonded to 2 fatty acids and a phosphate group

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17
Q

Describe amphiphatic nature of phospholipids

A

Positively charged head is hydrophilic

Hydrophobic tail repels water

18
Q

What is the main dietary lipid

A

Triacylglycerol

19
Q

Where is the main site of digestion

A

Small intestines

20
Q

What are some other dietary lipids

A

Phospholipids, cholesterol, free fatty acids and cholesterol ester

21
Q

What digests lipids and what is it promoted by

A

Lipids are digested by pancreatic enzymes called lipases and is promoted by emulsification by bile salts and peristalsis

22
Q

What are bile salts

A

Derivatives of cholesterol
Saves lipids coalescing in an aqueous enviroment
Act as a biological detergents to form emulsions and mixed micelles

23
Q

How do we digest TAG

A

Most degraded in small intestine by pancreatic lipase to monoacylglycerol and 2 FA

24
Q

What are cholesterol esters digested to

A

Cholesterol and free FA

25
Q

How are phospholipids digested and what too

A

Converted to FAs and lysophospholipids by hydrolysation

26
Q

Which of short, medium and long FAs require micelles for absorption

A

Long

27
Q

What is steatorrhea

A

Excess fat in faeces, stools float, have oily appearance and are foul smelling

28
Q

What happens if the gallbladder is removed

A

Inhibition of digestion and absorption of fats

29
Q

How is TAG stored in adipose cells

A

Droplets that constitute the depot fat

30
Q

Why is TAG the most efficient storage form of fuel

A

It’s highly reduced, nearly anhydrous

31
Q

How are FA released from stored TAG in adipose tissue

A

Hormone Sensitive Lipase (HSL) activated by phosphorylation in response to epinephrine. High plasma glucose and insulin promote dephosphorylation of lipase (deactivation)

32
Q

How are FA transported in the blood

A

Free FA transported through blood in complex with serum albumin

33
Q

What is the most abundant plasma protein and how many FA binding sites does it have

A

Albumin, 2-7

34
Q

What occurs when there is too much LDL

A

Atherosclerosis, lipid develops into fatty streaks and plaque within an artery

35
Q

What does the beta oxidation pathway do

A

Degrades fatty acids 2 carbons at a time

Produces acetyl CoA and NADH and FADH2

36
Q

Where does beta oxidation occur

A

Mitochondrial matrix

37
Q

What happens in beta oxidation?

A

Three stages:

  1. activation of fatty acids in cystole
  2. transport by carnatine shuttle into the mitochondria
  3. degradation to 2 carbon gragments (as acetyl CoA) in the mitochondrial matrix - energy
38
Q

What happens in fatty acid activation

A

Fatty acid activated to form fatty acyl CoA in cytoplasm

39
Q

What is the Carnitine shuttle

A

Major site of regulation
Prevents synthesis and degradation occurring simultaneously
Carton from diet or made from lysine/methionine in liver/kidney

40
Q

What is CAT-1

A

Carnitine palmitoyl-transferase deficiency
A carnatine associated defect in liver fatty acid beta oxidation impairs the livers capacity to use fatty acids as fuels and puts and extra burden on its capacity to generate glucose through glucneogenesis

41
Q

What happens during degradation stage of beta oxidation

A
  1. Dehydrogenation to produce FADHs
  2. Hydration
  3. Dehydrogenation to produce NADH
  4. Thiolysis (cleaved) to produce acetyl CoA