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Lipids and Lipid Metabolism > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

what is lipolysis

A

triglycerides are broken down to glycerol and other fatty acids

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2
Q

What are lipids

A
  • constituents of cell and organelle membranes
    (phospholipids and sphingolipids)
- lipids include:
 fatty acids
triacylglycerols
 lipid soluble vitamins
 steroid hormones
prostaglandins
waxes and their derivatives
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3
Q

Describe the characteristics of lipids

A
  • some ampiphathic

- some non polar

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4
Q

Describe fatty acids

A
  • have a polar end containing a carboxyl group
  • non polar tail
  • forms micelles in water
  • may be saturated( single bonds only) or unsaturated(some double bonds)
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5
Q

How do the double bonds on the non polar hydrocarbon chain affect the fatty acid

A

forms kinks on the tail; making it less rigid

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6
Q

What is fat and oil made of

A

when three fatty acids are esterified into glycerol

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7
Q

true or false; fats rich in unsaturated fatty acids are typically oils

A

true

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8
Q

How do the fats in the body arise

A

either from the biosynthesis of acetyl CoA or from breakdown of fats and phospholipids

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9
Q

What is the main source of energy derived from lipids

A

oxidation of fatty acids

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10
Q

What does dietary fat mainly consist of

A

triacylglycerides
phospholipids
cholesterol esters

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11
Q

How many carbons are in myristic acid (SA)

A

14

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12
Q

how many carbons are in stearic acid (SA)

A

18

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13
Q

how many carbons are in palmitic acid (SA)

A

16

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14
Q

how many carbons are in archidic acid (SA)

A

20

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15
Q

how many carbons are in lauric acid (SA)

A

12

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16
Q

Why are fats difficult to digest and absorb

A

due to hydrophobicity

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17
Q

What do bile acids do to lipids

A

bile acids are secreted from gall bladder and help emulsify the constituent lipids forming micelles

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18
Q

Why are micelles important

A

permits soluble enzymes (lipases) secreted by the gut to hydrolyze triglycerides to fatty acids and glycerol

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19
Q

true or false; lipids are very hydrophobic and will pass through membranes easily

A

true

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20
Q

how must lipids be packaged with they have to travel in the blood and lymph

A

lipoprotein complexes

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21
Q

how must lipids be packaged if they have to travel in the digestive tract

A

micelles

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22
Q

What do phospholipases hydrolyze

A

phospholipids

—> fatty acids

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23
Q

What do specific esterases release from cholesterol esters

A

cholesterol and constituent fatty acids

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24
Q

What transports free fatty acids in the bloodstream

A

free fatty acids (FFAs) are bound to serum albumin; can be directly absorbed by cells

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25
Q

In starved state how are FFAs generated

A

by hydrolysis of triacylglycerides in adipose tissues

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26
Q

What are adipose tissues

A
  • contains adipocytes ( fat cells)
  • subcutaneous fat
  • white and brown forms
  • found around liver and mammary glands
27
Q

true or false; FFAs can be directly absorbed by cells

A

true

28
Q

What are short chain fatty acids

A
  • can pass directly across epithelial cells from the gut lumen into the blood stream
  • in the bloodstream they are bound to serum albumin and transported
29
Q

What are long chain fatty acids

A
  • are bound to a fatty acid binding protein, then re-esterified to glycerol in the gut epithelium
  • then secreted into the blood in the form of chylomicrons which also transport phospholipids and cholesterol
  • rarely found in free form
30
Q

What are chylomicrons

A
  • assembled in the gut epithelial cells

- composed of TG (triacylglycerides), PG (phopholipids), cholesterol, lipoprotein

31
Q

how do chylomicrons travel

A

from the lymph into the blood

32
Q

true or false; some TG are hydrolyzed by lipoprotein lipase

A

true

33
Q

true or false; chylomicron remnants are recovered by the liver then recycled to to other lipoprotiens

A

true

34
Q

What fatty acids, essential to the human diet cannot be synthesized by human therefore must be present in their diet

A

Linoleic

Linolenic

Arachidonic

35
Q

What does linoleic and linolenic fatty acids do

A

are necessary components of membrane phospholipids; required to maintain membrane fluidity

36
Q

Why is Arachidonic fatty acid important

A
  • a membrane constituent

- additionally serves as a precursor for the prostaglandins and leukotrienes

37
Q

true or false; lipid in the diet also assists the absorption of fat soluble vitamins and improves food taste and texture

A

true

38
Q

What are VLDLs

A

very low density lipoprotein

39
Q

Where are VLDLs and other lipoprotein complexes made

A
  • assembled and released from the liver
40
Q

what does IDLs mean

A

intermediate density lipoprotein

41
Q

what does LDLs mean

A

low density lipoprotein

42
Q

what does HDLs mean

A

high density lipoprotein

43
Q

What do lipases catalyze

A

the hydrolysis of bonds between the fatty acyl group and glycerol of of triacylglycerol

44
Q

What do phospholipases catalyze

A

hydrolysis of bonds between fatty acyl groups and phosphoglycerols at specific sites

45
Q

How are soaps made

A

result from saponification of triglycerides with aqueous NaOH

these sodium salts of fatty acids are then precipitated with metal ions such as Ca2+, Mg2+, Fe 3+

46
Q

What are types of lipids

A 
waxes
sphingolipids
glycolipids
cholesterol
steroids
sex hormones
bile salts 
phospholipids
fat soluble vitamins
many signalling compounds
47
Q

What are waxes

A

often mixture of esters of long carboxylic acids and alcohols
found as protective coatings for plants and animals

48
Q

What is cetyl palmitate used for

A

cosmetics

49
Q

what is myricyl cerotate

A

furniture

50
Q

What are sphingolipids

A
  • contain sphigosine
    ( a long chain amino alcohol sphingosine)
  • found in plants and animals
  • abundant in the nervous system
  • have structural similarity to the phospholipids
51
Q

what is sphingomyelin important for

A
  • the myelin sheath
52
Q

What are glycolipids

A
  • compounds which a carbohydrate is bound to an OH of the lipid
  • most cases the sugar is galactose or glucose
  • many glycolipids are derived from ceramides
53
Q

what are gangliosides

A

glycolipids with complex carbohydrate moiety that contains more than 3 sugars

54
Q

What are the three types of gangliosides

A

Gm1
Gm2
gm3

55
Q

What are steroids

A

a group of lipids that have fused ring structure of 3 six membered ring and 1 five membered ring

56
Q

true or false; triacylglycerols are transported through the bloodstream via VLDLs

A

true

57
Q

true or false; lipids are repackaged in the liver with apolipoproteins in the liver to form lipoprotein complexes

A

true

58
Q

what happens after lipids are repackaged with liver apolipoproteins as lipoprotein complexes

A

the lipoprotein complexes are then exported back into the bloodstream to be carried to peripheral tissues as VLDLs

59
Q

true or false; muscles release lipoprotein lipase to hydrolyze bound triacylglycerides

A

true

60
Q

true or false; as the lipid is progressively removed the lipoprotein particles becomes smaller and consequently somewhat more dense –> LDLs

A

true

61
Q

true or false; LDLs contain a higher level of cholesterol than VLDLs

A

true

62
Q

What role do HDLs play

A

they are produced by the liver as well

- remove cholesterol from cell membranes and return them to liver

63
Q

true or false; in response to hormonal signals in the starved state, triacylglycerols in adipose tissue are hydrolyzed to yield FFAs and glycerol

A

true

64
Q

what does fatty acyl CoA synthetase do

A

it uses ATP to convert FFAs into their more soluble CoA thioesters

Lipids and Lipid Metabolism (4 decks)

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