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Biochemistry > Chapter 12 : Lipids > Flashcards

Chapter 12 : Lipids Flashcards

1
Q

The monomer of lipids is

A

fatty acids

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2
Q

What are fatty acids

A

Long hydrocarbon chains with a carboxylic acid on one end

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3
Q

What are the two types of fatty acids ?

A

Saturated or unsaturated

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4
Q

Saturated fatty acids are made of

A

Single carbon to carbon bonds

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5
Q

Unsaturated fatty acids are made of

A

One or more C-C double bonds

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6
Q

Which type of fatty acid is more abundant in nature?

A

Unsaturated fatty acids

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7
Q

The double bonds in unsaturated fatty acids cause

A

a cis conformation , causing them to kink by packing closely together. It also gives a lower melting range temperature .

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8
Q

What are the functions of lipids ?

A
  • energy storage
  • insulation and heat regulation
  • membrane composition
  • cell messengers
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9
Q

What are the four types of lipids

A
  • triglycercides
  • phospholipids
  • steroids
  • waxes
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10
Q

What is the most common type of lipid ?

A

Triglyceride

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11
Q

Where are triglycerides most commonly found ?

A

butter, lard, margarines and oils

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12
Q

What is the structure of a triglycerol ?

A

1 glycerol molecule and three fatty acids

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13
Q

True or false, triacylglycerols take up more space than polysaccharides

A

False, because triacylglycerols are hydrophobic, they take up less space

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14
Q

What are the three types of membrane lipids

A
  • phospholipids
  • glycolipids
  • cholesterol
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15
Q

Phospholipids

A

-forms the cell membrane , phospholipid bilayer

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16
Q

Structure of phospholipid

A

Hydrophilic phosphate head , hydrophobic tails

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17
Q

How is the glycerol bonded to the fatty acids in phospholipids ?

A

The hydroxyl group the glycerol sis bonded to the carboxyl group of the fatty acids.

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18
Q

The phosphatidate is phospholipids is made up of

A

The glycerol backbone, fatty acid, and phosphoric acid

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19
Q

Sphingomyelin is a type of

A

membrane phospholipid

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20
Q

Instead of glycerol, sphingomylein uses :

A

spingosine

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21
Q

To form sphingomyelin :

A

sphingosine is linked to the fatty acid though an amide bond

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22
Q

What is the primary hydroxyl group of spingosine ?

A

phosphorylcholine

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23
Q

Glycolipids

A

Contains a sphingosine backbone, fatty acid , and one or more sugar residues

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24
Q

The fatty acid is joined to the sphingosine backbone through what type of bond?

A

amide linkage

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25
The primary hydroxyl group in glycolipids is linked to a
Sugar | Ex) cerebroside or gangliosides
26
Cerebrosides
A glycolipid which contains simple sugar attatchments such as glucose or galactose
27
Gangliosides
A glycolipid that have more complex sugar attachments of branched sugar molecules
28
Cholesterol serves as a type of
steroid
29
Functions of steroids
- Hormones for chemical messaging | - No fatty acids, C and H are in rings
30
Cholesterol is synthesized from molecules called
terpenes
31
Terpenes
Any large group of large volatile unsaturated hydrocarbons found in essential oils of plants
32
Polyprenols
natural long chain of isoprenoid alcohols that function as natural bioregulators, found in various plant tissues
33
Most steriods are found in the form of
5 or 6 membered rings
34
The most common steroid found in nature is
cholesterol
35
What are the 5 classes of steroids ?
- Androgens - Estrogens - Progestins - glucocorticoids & mineralocorticoids - bile acids
36
Function of androgens and estrogen
- Mediate the development of sexual characteristics and functions in animals
37
Progestins
Participate in the control of the menstrual cycle and pregnancy
38
Bile Acids
Detergents produced by the gall bladder and added to bile to assist in absorption of lipids in the intestine
39
Glucocorticoids
Participate in the control of carbohydrate protein and lipid metabolism
40
Mineralcorticoids
Regulates the balance of salts such as Na , K and Cl in tissues
41
Other than the backbone, what is the difference between glycolipids and phospholipids
Phospholipids have a phosphate group esterified to the hydroxyl group on the 3rd carbon while glycolipids have at least one sugar esterfied to the hydroxyl group on the 3rd carbon
42
Amphipathic
Having both a hydrophobic and hydrophilic end | ex) cell membranes
43
Hydrocarbon tails which are nonpolar are considered to be
hydrophobic
44
The phosphate and choline heads are considered to be
hydrophilic
45
In the cell membrane, the hydrophilic heads are facing which direction
The hydrophilic heads are in contact with the water while the hydrophobic sides avoid contact with the water
46
Micelles
Hydrophobic tails of the phospholipids face the center while the polar heads face towards the outside
47
Are lipid bilayers spontaneously or non-spontaneously formed ?
Spontaneously formed
48
How are lipid bilayers stabilized ?
- Hydrophobic interactions from fatty acids - Van der Waals attractive forces between hydrocarbon tails - Electrostatic and hydrogen bonding between the polar heads of molecules
49
Lipid bilayers are impermeable to
most ions and polar molecules
50
Based on the type of membrane, the ratio of ___ to _____ differs
lipid to protein
51
What are the two type of protein associations ?
Peripheral and integral
52
Peripheral
Extrinsic, proteins that do not penetrate far into the bilayer
53
How can peripheral proteins be dissociated from the membrane
Salt solutions or changes in pH
54
Integral proteins
Intrinsic, proteins that extend all the way across the membrane
55
How can integral proteins be dissociated from the membrane?
They can be removed only by disrupting the lipid bilayer itself
56
α-helical membrane proteins
Most common transmembrane protein
57
Example of a α-helical membrane protein
Bacteriohodopsin which is found in bacteria to help transport protons across the membrane
58
prostaglandin | H2-synthase-1
Example of an α-helical membrane protein that is used as a membrane anchor , not spanning across the entire membrane
59
β-barrel membrane Proteins
Found on the outer membranes of bacteria , mitochondria for ion transport , passive nutrient intake, membrane anchor
60
β-barrel membrane Proteins are arranged in a
antiparallel fashion
61
On the inner surface of the β-barrel, there is ___ and on the outer surface , there is a ____ __
water , hydrophobic surface
62
What are the four types of lipid anchors
- amide -linked myistoyl anchors - thioester- linked fatty acyl anchors - thioether- linked prenyl anchors - glycosyl phosphartidylinositol anchors
63
Amide- linked myristoyl anchors
myristic acid ( a lipid) that may be linked by an amide bond to the α-amino group of the N-terminal glycine of certain proteins.
64
Thioester-linked Fatty Acyl Anchors
palmitoyl group ( a lipid_ attatched through a thioester linkage to the side chained of cysteine and sometimes serine or threonine
65
Thioether-Linked Prenyl Anchors
Long chains of isoprenoid groups which occurs at the cysteine residue which is then cleaved by a protease leaving the C terminus on the anchor
66
Glycosyl Phosphatidylinositol Anchors
The phophatidylinositol (lipid) is attached to an oligiosaccharide which is attatched to an ethanolamine. The enthanolamine is atatched to the C terminal of the amino acid
67
What features of the phospholipid molecules cause them to form a bilayer membrane spontaneously when placed in an aqueous environment
The phospholipid structure has both a hydrophilic head and a hydrophobic tail allowing the tails to be placed away from water and the heads toward water
68
What are two common secondary structures often found in transmembrane proteins
The α-helix and the β-sheet are often found in | transmembrane proteins.
69
How can bacteria change the fluidity of the cell membrane
By adjusting the number of double bonds and the chain length of its lipids
70
How can eukaryotes change the fluidity of the cellmembrane
Changing the amount of cholesterol inserted into the membrane
71
Most proteins move ___ through the membrane
laterally or can flip flop from one side to the other
72
Membranes have what type of symmetry
Transverse asymmetry. | * Sugars are only on the extracellular side of the membrane
73
Amine containing phospholipids are only on which side
cytoplasmic side
74
Choline containing phospholipids and sphingolipids are only on the
outer side of the membrane
75
If there is a loss of lipid asymmetry
It could trigger apoptosis
76
Flippases
ATP dependent that flip the PS and sometimes the PE from the outer layer to the inner layer
77
Floppases
ATP dependent that transport lipids, PC and sphingomyelin from inner to outer membrane
78
In what ways can the membrane be asymmetric ?
- Proteins on either side could be different or phospholipids could be different compared from the inner to the outer membrane
79
Can lipids be moved from one side to the other
Phospholipids can be moved by using enzymes called flippases and floppases . proteins cannot be moved from one side to the other.

Biochemistry (8 decks)

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