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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
Q

The primary hydroxyl group in glycolipids is linked to a

A

Sugar

Ex) cerebroside or gangliosides

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26
Q

Cerebrosides

A

A glycolipid which contains simple sugar attatchments such as glucose or galactose

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27
Q

Gangliosides

A

A glycolipid that have more complex sugar attachments of branched sugar molecules

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28
Q

Cholesterol serves as a type of

A

steroid

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29
Q

Functions of steroids

A
  • Hormones for chemical messaging

- No fatty acids, C and H are in rings

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30
Q

Cholesterol is synthesized from molecules called

A

terpenes

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31
Q

Terpenes

A

Any large group of large volatile unsaturated hydrocarbons found in essential oils of plants

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32
Q

Polyprenols

A

natural long chain of isoprenoid alcohols that function as natural bioregulators, found in various plant tissues

33
Q

Most steriods are found in the form of

A

5 or 6 membered rings

34
Q

The most common steroid found in nature is

A

cholesterol

35
Q

What are the 5 classes of steroids ?

A
  • Androgens
  • Estrogens
  • Progestins
  • glucocorticoids & mineralocorticoids
  • bile acids
36
Q

Function of androgens and estrogen

A
  • Mediate the development of sexual characteristics and functions in animals
37
Q

Progestins

A

Participate in the control of the menstrual cycle and pregnancy

38
Q

Bile Acids

A

Detergents produced by the gall bladder and added to bile to assist in absorption of lipids in the intestine

39
Q

Glucocorticoids

A

Participate in the control of carbohydrate protein and lipid metabolism

40
Q

Mineralcorticoids

A

Regulates the balance of salts such as Na , K and Cl in tissues

41
Q

Other than the backbone, what is the difference between glycolipids and phospholipids

A

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
Q

Amphipathic

A

Having both a hydrophobic and hydrophilic end

ex) cell membranes

43
Q

Hydrocarbon tails which are nonpolar are considered to be

A

hydrophobic

44
Q

The phosphate and choline heads are considered to be

A

hydrophilic

45
Q

In the cell membrane, the hydrophilic heads are facing which direction

A

The hydrophilic heads are in contact with the water while the hydrophobic sides avoid contact with the water

46
Q

Micelles

A

Hydrophobic tails of the phospholipids face the center while the polar heads face towards the outside

47
Q

Are lipid bilayers spontaneously or non-spontaneously formed ?

A

Spontaneously formed

48
Q

How are lipid bilayers stabilized ?

A
  • Hydrophobic interactions from fatty acids
  • Van der Waals attractive forces between hydrocarbon tails
  • Electrostatic and hydrogen bonding between the polar heads of molecules
49
Q

Lipid bilayers are impermeable to

A

most ions and polar molecules

50
Q

Based on the type of membrane, the ratio of ___ to _____ differs

A

lipid to protein

51
Q

What are the two type of protein associations ?

A

Peripheral and integral

52
Q

Peripheral

A

Extrinsic, proteins that do not penetrate far into the bilayer

53
Q

How can peripheral proteins be dissociated from the membrane

A

Salt solutions or changes in pH

54
Q

Integral proteins

A

Intrinsic, proteins that extend all the way across the membrane

55
Q

How can integral proteins be dissociated from the membrane?

A

They can be removed only by disrupting the lipid bilayer itself

56
Q

α-helical membrane proteins

A

Most common transmembrane protein

57
Q

Example of a α-helical membrane protein

A

Bacteriohodopsin which is found in bacteria to help transport protons across the membrane

58
Q

prostaglandin

H2-synthase-1

A

Example of an α-helical membrane protein that is used as a membrane anchor , not spanning across the entire membrane

59
Q

β-barrel membrane Proteins

A

Found on the outer membranes of bacteria , mitochondria for ion transport , passive nutrient intake, membrane anchor

60
Q

β-barrel membrane Proteins are arranged in a

A

antiparallel fashion

61
Q

On the inner surface of the β-barrel, there is ___ and on the outer surface , there is a ____ __

A

water , hydrophobic surface

62
Q

What are the four types of lipid anchors

A
  • amide -linked myistoyl anchors
  • thioester- linked fatty acyl anchors
  • thioether- linked prenyl anchors
  • glycosyl phosphartidylinositol anchors
63
Q

Amide- linked myristoyl anchors

A

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
Q

Thioester-linked Fatty Acyl Anchors

A

palmitoyl group ( a lipid_ attatched through a thioester linkage to the side chained of cysteine and sometimes serine or threonine

65
Q

Thioether-Linked Prenyl Anchors

A

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
Q

Glycosyl Phosphatidylinositol Anchors

A

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
Q

What features of the phospholipid molecules cause them to form a bilayer membrane spontaneously when placed in an aqueous environment

A

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
Q

What are two common secondary structures often found in transmembrane proteins

A

The α-helix and the β-sheet are often found in

transmembrane proteins.

69
Q

How can bacteria change the fluidity of the cell membrane

A

By adjusting the number of double bonds and the chain length of its lipids

70
Q

How can eukaryotes change the fluidity of the cellmembrane

A

Changing the amount of cholesterol inserted into the membrane

71
Q

Most proteins move ___ through the membrane

A

laterally or can flip flop from one side to the other

72
Q

Membranes have what type of symmetry

A

Transverse asymmetry.

* Sugars are only on the extracellular side of the membrane

73
Q

Amine containing phospholipids are only on which side

A

cytoplasmic side

74
Q

Choline containing phospholipids and sphingolipids are only on the

A

outer side of the membrane

75
Q

If there is a loss of lipid asymmetry

A

It could trigger apoptosis

76
Q

Flippases

A

ATP dependent that flip the PS and sometimes the PE from the outer layer to the inner layer

77
Q

Floppases

A

ATP dependent that transport lipids, PC and sphingomyelin from inner to outer membrane

78
Q

In what ways can the membrane be asymmetric ?

A
  • Proteins on either side could be different or phospholipids could be different compared from the inner to the outer membrane
79
Q

Can lipids be moved from one side to the other

A

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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