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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
In starved state how are FFAs generated
by hydrolysis of triacylglycerides in adipose tissues
26
What are adipose tissues
- contains adipocytes ( fat cells) - subcutaneous fat - white and brown forms - found around liver and mammary glands
27
true or false; FFAs can be directly absorbed by cells
true
28
What are short chain fatty acids
- 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
What are long chain fatty acids
- 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
What are chylomicrons
- assembled in the gut epithelial cells | - composed of TG (triacylglycerides), PG (phopholipids), cholesterol, lipoprotein
31
how do chylomicrons travel
from the lymph into the blood
32
true or false; some TG are hydrolyzed by lipoprotein lipase
true
33
true or false; chylomicron remnants are recovered by the liver then recycled to to other lipoprotiens
true
34
What fatty acids, essential to the human diet cannot be synthesized by human therefore must be present in their diet
Linoleic Linolenic Arachidonic
35
What does linoleic and linolenic fatty acids do
are necessary components of membrane phospholipids; required to maintain membrane fluidity
36
Why is Arachidonic fatty acid important
- a membrane constituent | - additionally serves as a precursor for the prostaglandins and leukotrienes
37
true or false; lipid in the diet also assists the absorption of fat soluble vitamins and improves food taste and texture
true
38
What are VLDLs
very low density lipoprotein
39
Where are VLDLs and other lipoprotein complexes made
- assembled and released from the liver
40
what does IDLs mean
intermediate density lipoprotein
41
what does LDLs mean
low density lipoprotein
42
what does HDLs mean
high density lipoprotein
43
What do lipases catalyze
the hydrolysis of bonds between the fatty acyl group and glycerol of of triacylglycerol
44
What do phospholipases catalyze
hydrolysis of bonds between fatty acyl groups and phosphoglycerols at specific sites
45
How are soaps made
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
What are types of lipids
``` waxes sphingolipids glycolipids cholesterol steroids sex hormones bile salts phospholipids fat soluble vitamins many signalling compounds ```
47
What are waxes
often mixture of esters of long carboxylic acids and alcohols found as protective coatings for plants and animals
48
What is cetyl palmitate used for
cosmetics
49
what is myricyl cerotate
furniture
50
What are sphingolipids
- 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
what is sphingomyelin important for
- the myelin sheath
52
What are glycolipids
- 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
what are gangliosides
glycolipids with complex carbohydrate moiety that contains more than 3 sugars
54
What are the three types of gangliosides
Gm1 Gm2 gm3
55
What are steroids
a group of lipids that have fused ring structure of 3 six membered ring and 1 five membered ring
56
true or false; triacylglycerols are transported through the bloodstream via VLDLs
true
57
true or false; lipids are repackaged in the liver with apolipoproteins in the liver to form lipoprotein complexes
true
58
what happens after lipids are repackaged with liver apolipoproteins as lipoprotein complexes
the lipoprotein complexes are then exported back into the bloodstream to be carried to peripheral tissues as VLDLs
59
true or false; muscles release lipoprotein lipase to hydrolyze bound triacylglycerides
true
60
true or false; as the lipid is progressively removed the lipoprotein particles becomes smaller and consequently somewhat more dense --> LDLs
true
61
true or false; LDLs contain a higher level of cholesterol than VLDLs
true
62
What role do HDLs play
they are produced by the liver as well | - remove cholesterol from cell membranes and return them to liver
63
true or false; in response to hormonal signals in the starved state, triacylglycerols in adipose tissue are hydrolyzed to yield FFAs and glycerol
true
64
what does fatty acyl CoA synthetase do
it uses ATP to convert FFAs into their more soluble CoA thioesters

Lipids and Lipid Metabolism (4 decks)

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