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SIJ1003 > LIPIDS > Flashcards

LIPIDS Flashcards

1
Q

What is lipid?

A

-molecules that contain hydrocarbons
-main component of the structure n functions of living cells

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2
Q

list the general functions of lipids

A

 Main molecule for energy storage (triglyceride/triacylglycerol)–
lipids are non polar.
 Polar lipids are important components of the biological membrane–
forms lipid bilayer.
 Steroids
 Chlorophyll, carotenoid and retinol.
 As fat soluble vitamins, A, D, E and K.
 As electron transport carriers in the chloroplast and mitochondria
(ubiquinone (UQ or CoQ) and plastoquinone (PQ)).
 As signal molecules – prostaglandins

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3
Q

what are the classifications of lipids?

A
  1. Fatty acids (FA)
  2. Triacylglycerol / triglyceride (TG) / neutral lipid
  3. Phospholipid / glycerophospholipid
  4. Sphingolipid
  5. Waxes
  6. Steroids / cholesterol
  7. Terpenoids / terpenes
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4
Q

describe fatty acids

A
  • Long chain carboxyl acids (4C – 30C).
  • Has long aliphatic chain – not branched.
  • One end has a methyl group and the other a carboxyl group.
  • Amphiphatic (two opposite properties) – the tail is hydrophobic
    while the head is weakly hydrophilic.
  • In nature they are esterified to glycerol – because they are
    poisonous if free.
  • Most have even number of carbons (16C-22C) with single C-C
    bonds
  • Can be saturated (no double bonds) or unsaturated (1 – 6 double
    bonds).
  • Mostly (>50%) are unsaturated.
  • Double bonds are in the cis configuration (not trans) and
    unconjugated (linked by a methylene unit , – CH2
    -).
  • Fatty acids with <12 carbons are soluble in water.
  • They are soluble in dilute NaOH/KOH to yield soap;
    (the hydrophobic end of FA is called the omega end while the hydrophilic end is called delta end. read FA from omega end)
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5
Q

Examples of Unsaturated Fatty ACID?

A

-FA is divided into two : monounsaturated fatty acid (MUFA) & polyunsaturated fatty acid (PUFA)

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6
Q

example of PUFA

A

1) omega 3
alpha-linolenic acid:
-plant-omega 3
-dietary precursor for omega-3 eicosapentaenoic acid (EPA), dicosapentaenoic acid (DPA) & docosahexanoic acid (DHA)
-can be found in seafood

2) omega 6
arachidonic acid
linoleic acid :
-found in oil, corn, beans, meat, eggs, soybeans

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7
Q

example of MUFA

A

1)omega 9
oleic acid :
-found in canola oil/olive oil

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8
Q

what is trans fat?

A

-trans fat is the common name for unsaturated fat with trans-isomer FA. (straight molecule)
-may be MUFA or PUFA but NEVER SATURATED

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9
Q

effects of trans fat consumption?

A

-increases risk of coronary heart disease by raising LDL cholesterol & lowering levels of HDL.

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10
Q

describe triacylglycerol/ triglyceride (TG)

A

-found in fats n oils in animals n plants
-made up of 1 glycerol + 3 fatty acids
-insoluble in water
-FA triesters of glycerol
-act as energy storage
-can be simple/ mixed triacylglycerol
-when hydrolyzed with alkali, will yield soap
-commercially important for saponification
-substitues butter into PUFA margarines thru hydrogenation (double bonds > single bonds)
-leads to some cis double bonds > trans double bonds (may increase in blood cholesterol)

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11
Q

describe phospholipid/glycerophospholipid

A

-main lipid of biological membranes
-made up of a polar group, glycerol, phosphate and 2 fatty acids
-have hydrophilic head and hydrophobic tails

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12
Q

phospholipids/ glycerophospholipids is also known as?

A

phophoglyceride/ glycerol phosphatide

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13
Q

examples of polar groups that can be esterified to the phosphate group of phospholipid?

A

choline, ethanolamine, serine, inositol, glycerol etc

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14
Q

what happens when phospholipid + choline?

A

phosphotidyl choline

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15
Q

phospholipid + serine

A

phosphotidyl serine

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16
Q

phospholipid + ethanolamine

A

phosphotidyl ethanolamine

17
Q

what replaces glycerol that produces sphingolipids?

A

sphingosine = an 18C alcohol

18
Q

what happens when sphingosine + fatty acid?

A

ceramide, attach to C2

19
Q

what happens when ceramide + phosphocholine/ethanolamine at 1-OH goup ?

A

sphingomyelin is formed. (found in myelin sheath of nerve cells)

20
Q

what happens when ceramide + beta-galactose/glucose at the C1 where there is an OH group?

A

cerebroside is formed

21
Q

what happens when ceramide + oligosaccharide at the C1 where there is an OH group?

A

ganglioside is formed

22
Q

importance of glycosphingolipids/glycolipids-

A

-cell-cell recognition
-nerve impulse transmission
-tay-sachs disease in small children is where ganglioside GM2 accumulate resulting in early death
-

23
Q

what is waxes?

A

-simple lipids
-esters of long chain alcohols + long chain FAs
-has one weakly polar end
-FAs in waxes is usually saturated
-highly insoluble
-found in animal skins/ surface of certain fruits

24
Q

examples of waxes

A

-carnauba wax is from a palm tree in brazil (used for car polish)
-lanolin : wax from wool used in pharmaceutical industry - easily absorbed by human skin
-spermaceti - wax found in whales, made up of palmityl alcohol + palmitate

25
Q

describe steroid

A

-important group of terpenes

26
Q

what are the 5 hormones included in steroids?

A
  1. androgens (male sex characteristics ie. testosterone)
  2. estrogens (female sex characteristics ie. estradiol)
  3. progestrin (for period n pregnancy ie progesterone)
  4. glucocorticoid & mineralocorticoid
  5. bile acids
27
Q

example of glucocorticoid

A

cortisol : regulate lipid,carbs n protein metabolism

28
Q

functions of mineralocorticoid

A

regulate K+, Na+ and Cl- balance in tissues

29
Q

example of bile acids

A

cholic acid : helps in absorption of fats in the intestines

30
Q

what is cholesterol?

A

a very important n most common steroid

31
Q

describe the structure of cholesterol

A

-4 non aromatic rings (3 six membered rings + 1 five membered ring)
-1 hydroxyl group
-1 double bond
-1 side chain

32
Q

describe the cholesterol found in blood

A

-found as lipoprotein complexes (classified according to density)
1. chylomicrons (lowest density)
2. VLDL (very low density lipoprotein)
3. LDL (low density lipoprotein)
4. HDL (high density lipoprotein)
5. IDL

33
Q

function of chylomicrons?

A

transport cholesterol & dietary TG from intestines to liver

34
Q

functions of VLDL?

A

transports cholesterol esters (CE) and TG form liver to tissues (transfers more TG than CE)

35
Q

function of IDL?

A

same as VLDL (TG>CE)

36
Q

function of LDL

A

same as VLDL but transports CE > TG

37
Q

functions of HDL?

A

transports cholesterol from tissues to liver

38
Q

what can lipoprotein dysfunction cause?

A

-artherosclerosis (hardening of arteries) - yellow precipitation of cholesterol esters in the arterial walls
-it is progressive and can contribute to the formation of blood clots
-usually occurs in coronary artery

SIJ1003 (6 decks)

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