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Clin Sci: Biology sms1 > Lec 4: Lipids > Flashcards

Lec 4: Lipids Flashcards

1
Q

are lipids…

polymers?

non-polar/polar?

soluble/insoluble?

A

lipids are not polymers

they are non-polar

they are largely insoluble in water (but soluble in non-polar solvents)

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2
Q

what interactions cause lipids to group together in water?

A

hydrophobic

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3
Q

*NOTE*: Examples of lipids (5)

A

Fats

Oils

Waxes

Phospholipids

Steroids

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4
Q

what does a triglyceride contain?

A

3x fatty acids chains and 1x glycerol

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5
Q

what bonds link the fatty acid chains to the glycerol back bone ?

A

ester bond

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6
Q

in what process are triglycerides formed?

A

dehydration synthesis

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7
Q

in what reactions are triglycerides broken down?

what enzyme does this require?

A

hydrolysis

requires the enzyme: triglyceride lipase and H2O

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8
Q

where is triglyceride lipase found? what does it do?

A

found in the intestine

breaks down triglycerides

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9
Q

what is the difference between a saturated and unsaturated fatty acid?

give examples

A

Saturated = contain single [C-C] bonds e.g palmitate

Unsaturated = contain 1 or more double [C=C] bond e.g Oleate

*a diagram of a saturated fatty acid looks

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10
Q

what are FFAs?

A

free fatty acids that are not part of a triglyceride

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11
Q

how do you name Omega FFAs?

A

go from the location of the first double bond, cound from the methyl end

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12
Q

what FFAS are essential (=cannot be synthesised in the body)

Omega-3 (ω-3) fatty acids (e.g. α-linolenic acid)

Omega-6 (ω-6) fatty acids (e.g linoleic acid)

A
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13
Q

what do saturated and unsaturated fatty acids form?

A

SFAs form compact, closely packed triglycerides that are solid at toom temp e.g Palmitic acid (16 C) present in plant and animal fats

UFAs form loosely packed triglycerides due to cis double bonds, liquid at room temp e.g Olive oil (80% oleic acid (18 C)

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14
Q

what is the basic structure of steroids?

A

four fused carbon rings with various side groups attached

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15
Q

what is lanosterol and how is it formed?

A

lanosterol is the building block for all steroids

it is formed by the cyclization of sqaulene

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16
Q

give examples of steroids

A
  • cholesterol
  • sex hormones: Oestrogen, Progesterone, Testosterone
  • Corticosteroids: Aldosterone (mineralocorticoid), Cortisol (glucocorticoid)
  • Vitamin D (cholecalciferol) = a secosteroid
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17
Q

what is the name of this steroid? what type type of steroid does it fall under?

A

oestrogen *oest to the OHgen*

a sex hormone

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18
Q

what is the name of this steroid? what type of steroid does it fall under?

A

aldosterone *a lot of =O*

corticosteroids

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19
Q

what is the name of this steroid? what type of steroid does it fall under?

A

Vitamin D

a secosteroid

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20
Q

what are phospholipids?

A

Lipids with a phosphate group (PO42-) covalently bonded to the glycerol backbone instead of a fatty acid

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21
Q

which groups on a lipid molecule are polar and non polar

A

Phosphate group:

Polar Soluble in water (hydrophilic)

Head

Fatty acid groups:

Non-polar Insoluble

in water (hydrophobic) Tail

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22
Q

what are some examples of phospholipids

A

H (phosphatidic acid)

Ethanolamine (phosphatidylethanolamine)

Serine (phosphatidylserine)

Choline (phosphatidylcholine)

Inositol (phosphatidylinositol)

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23
Q

what is micelle?

A

a spherical arrangement of lipid molecules

24
Q

what is bilayer?

A

composed of two layers of lipids organised as a sheet

25
Q

what is a glycolipid?

A

a lipid covently attached to an oligosaccharide

It forms part of the cell membrane and glycocalyx

It determines ABO blood group

26
Q

what are lipoproteins?

A

Soluble complexes that transport lipids and synthesized in the liver

they are

27
Q

what is the glycocalyx

A

The glycocalyx, also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of some bacteria, epithelia and other cells.

28
Q

what is the central hydrophobic core of lipoprotein made up of?

A

Triglycerides

Esterified cholesterol (cholesteryl ester)

Small amounts of other lipids and fat soluble vitamins

29
Q

what is the external hydrophllic layer of a lipoprotein?

A
  • Phospholipids
  • Cholesterol (OH functional group outermost)
  • Apoproteins - stabilise structure and regulate enzymatic activity at the lipoprotein interface
30
Q

Order the following lipoprotein in terms of size and density;

chylomicron, VLDL (Very Low Density Lipoprotein), IDL (Intermediate Density Lipoprotein), LDL (Low Density Lipoprotein), HDL (High density lipoprotein)

A

Increasing in size order:

HDL, LDL, IDL, VLDL, chylomicron

density:

Chylomicron, VLDL, IDL, LDL, HDL

31
Q

what does chylomicrons do? what apoprotein does it contain?

A

Chylomicrons carry dietary fat from small intestine to the liver

contains the app: B-48

32
Q

what does a VLDL do? what apoprotein does it contain?

A

Produced in liver from synthesised triglycerides and chloestrol esters and carry fat to target tissues

appo E

33
Q

what is a IDL and LDL? which apoproteins do they contain?

A

they are VLDLs which have had their triglycerides removed

so they then become LDLs then IDLs

LDL apo: Apo E

IDL apo: Apo B-100

34
Q

what does a HDL do? which apoprotein does it contain?

A

HDL carries cholesterol to the liver (“good cholesterol” reducing atherosclerosis)

apo A-1

35
Q

what do apoproteins do?

A
  • stabilise structure and regulate enzymatic activity at the lipoprotein interface
36
Q

what is the name given to a condition where the arteries become clogged with fatty material forming sites of fatty deposition called plaque? what can this condition trigger?

A

atherosclerosis

heart attack/stroke

37
Q

how is atherosclerosis caused?

A
  • Development of atheroma (sits of plaque in your arteries)
  • deposition where hard scar forms ontop of the plaque
  • this narrows the vessel in which blood flows
  • this increases shear stress (friction from blood flow)
  • so if the plaque ruptures, it triggers thrombosis
  • closing of the vessel

Could result in ishemic heart attack/ischemic stroke

38
Q

where are triglycerides stored and what are they stored as?

A

TGs stored as lipid droplets

in the cytoplasm of adipocyte cells

in adipose tissue

39
Q

what is white adipose tissue and what is it’s function?

A
  • made up of white fat cells which have a lipid droplet in the cytoplasm
  • cushions internal organs like a shock absorber
  • gives insulation, protecting internal organs from temperature changes and reducing skin heat loss
40
Q

what is brown adpisose tissue and what is it’s function?

A

brown adipose tissue is made up of brown fat cells

which arise because off the mitochondria that generate heat and the numerous fat vacuoles

-therefore they are useful for warmth

41
Q

where are the white adipose tissue locatated?

A
42
Q

where is the brown adipose tissue located?

A

*Image shows Brown adipose depots in patients identified by deoxy-2-[18F]fluoro-Dglucose ([18F]FDG)-positron emission tomography (PET)

43
Q

what diseases are excess adipose tissue involved in?

A

atherosclerosis-narrowing of blood vessel

thrombosis- clotting of circulating blood

stenosis- abnormal narrowing of blood vessel

aneurysms - blood filled bulge in a blood vessel wall

44
Q

excess adipose tissue is now considered to be a major endrocine organ. What does this mean?

A

produces pro-inflammatory hormones such as leptin (affects appetite) and the cytokine TNFa (affects tissue)

45
Q

what part of a nerve cell does a phospolipid form? how does this cell affect the function of the cell?

A

-phospholipids form the myelin insulation around nerve fibres

myelin increases the speed of nervous impulses

46
Q

what cells produce myelin and how do they produce it?

A

Schwann cells produce myelin peripherally (nerves and ganglia outside cns)

Oligodendrocytes produce myelin centrally (brain/spinal cord)

47
Q

what do vitamin A,D,E and K have in common?

A

they are all fat soluble

48
Q

what are examples of Vitamin A and how does it benefit the body?

A

retinol/retinoic acid/carotenoids

gives you healthy teeth, skin, sight

49
Q

what are examples of vitamin D and how does it benefit the body?

A

cholecalciferol and derivatives

Helps body absorb Ca2+ for healthy bones

50
Q

what is vitamin E and how does it benefit the body?

A

a tocopherol (antioxidant) found in oils Anti-oxidant,

protects cells from damage

51
Q

what are examples of vitamin K? how does it benefit the body?

A

phylloquinone and menaquinone Important for coagulation of blood

52
Q

what are eicosanoids?

A

they are 20 carbon fatty acids

dervied from omega-3 and omega-6 fatty acids

53
Q

what are the three types of eicosanoid hormones?

A

Prostaglandins (inflammation, vascular tone)

Leukotrienes (asthma and allergy)

Thromboxanes (vascular tone, platelet aggregation)

54
Q

how do lipids prevent moisture loss?

A
  • skin moisture loss is prevented by lipid layers
  • comeocytes (skin cells) are held together by lipid rich matrix (like a glue) that holds the skin together
55
Q

how do lipids reduce moisture loss from the cornea?

A
  • the eye has several different layers
  • the lipid (oil) layer is hyrdophobic which lubricates and prevents evaporation from the eye
  • then you have the meibormian gland which create a lipid tear film
56
Q

what benefits do lipids have?

A

phospholipid bilayer- provides protection from surrounding environment and anchoring to extracellular structures and other cells required for tissue formation

TGs and FFAs- energy rich C-H bonds available for chemical reactions

WAT- insulators and protection from temperature changes

BAT- generating body heat

phospolipid- form myelin which increase speed of nerve impulses

lipids- reduce skin moisture

57
Q
A

Clin Sci: Biology sms1 (11 decks)

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