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Biochemistry I > Biochemistry Midterm 2.3 - Lipids/Membrane > Flashcards

Biochemistry Midterm 2.3 - Lipids/Membrane Flashcards

1
Q

lipids are defined by

A

solubility properties, fats are lipids, not all lipids are fats

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2
Q

fatty acids description and what they are found in

A

amphipathic, 3-35 carbons tail
at pH 7 carboxyl group is ionized
found in complex lipids (structural and storage) and micelles

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3
Q

oleic acid systematic name

A

cis-9-octadecenoic acid

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4
Q

fatty acid nomenclature

A

numbering of carbons starts from carboxyl end (reactive end) 𝚫
number carbons start from methyl end in nutrition omega Ο‰
# of carbons: # of double bonds ^ 𝚫 # 1st carbon of double bond
ex. 18:1^𝚫9 = cis-9-octadecenoic acid

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5
Q

linoleic acid in formula
alpha-linolenic acid formula

A

18:2^𝚫9,12
18:3^𝚫9,12,15

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6
Q

melting point increases
solubility decreases

A

Melting point :
1) decreasing double bonds/increased saturation
2) increasing chain length
Solubility:
1) decreases as chain length increases

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7
Q

saturated fatty acids

A

pack in an tight, ordered way
increased van der waals interactions
increased melting temp, takes more thermal energy to disrupt forces
cis bonds make for kinks that lower packing/melting temp

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8
Q

process that changes a cis alkene to a trans alkene

A

partial hydrogenation and cis alkene isomerization

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9
Q

biological health consequences of saturated fat and trans fat

A

saturated fat increase cholesterol by providing proper packing domains for cholesterol (LDL)
trans fats do the same and increase cell membrane rigidity
we don’t have the enzymes to break down trans fat bonds

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10
Q

simple triacylglycerol

A

a triglyceride with 3 fatty acids of the same type

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11
Q

enzyme that adds FA to glycerol and takes FA off
type of bond formed

A

acyl transferase and lipase
between the carboxyl end of a fatty acid and glycerol backbone is an ester bond formed by condensation reaction

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12
Q

fat and oil definition

A

solid triacylglycerides, liquid triacylglycerides

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13
Q

triacylglycerides description and why they are good for energy storage

A

storage lipid in animals (fats) and plants (seeds)
non polar, less soluble than fatty acids due to esterification of carboxyl groups
good for energy storage because more energy per carbon (reduced) and carry less water

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14
Q

how to make soap

A

saponification: add strong base to triglycerides to form glycerol and crude soap

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15
Q

waxes decription

A

esters of long chain fatty acids (saturated and unsaturated) with long chain alcohols (no glycerol back bone)
used as storage in plankton, waterproofing, and protection from evaporation
high melting point

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16
Q

highest lipid types in plasma, organelles and lysosomes

A

cholesterol, phosphatidylcholine, and sphingolipids

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17
Q

glycerophospholipids description

A

glycerol backbone, 2 fatty acids and a phosphate + head group on C3
primary structure in cell membranes
phosphate group is negatively charged at pH 7

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18
Q

phosphatidic acid

A

base form of glycerophospholipids
glycerophospholipid with 2 fatty acids on C1/C2 and an H attached to phosphate group as the head group

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19
Q

lysophosphatidatic acid

A

phosphate group attached to a glycerol backbone and 1 FA on C1

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20
Q

head group for phosphatidylethanolamine

A

amine containing, net charge 0 at pH 7

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21
Q

phosphatidylcholine
bonds
head group

A

major cell membrane component in most eukaryotes but prokaryotes can’t synthesis it
ester bonds between glycerol and FA and glycerol and phosphate, and phosphoester bond between phosphate and head group
amide containing, net charge of 0 at pH 7

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22
Q

head group for phosphatidylserine

A

carboxylate and amine containing, net charge -1 at pH 7

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23
Q

head group for phosphatidylglycerol

A

alcohol groups, net charge -1 at pH 7

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24
Q

head group for phosphatidylinositol

A

cyclic, net charge -4 at pH 7

25
Q

cardiolipin head group

A

the large one, non cyclic, net charge -2 at pH 7

26
Q

in vitro DNA synthesis requires:

A

2 Mg2+ ions, incoming nucleotide triphosphate, a 3’-OH group that with act as a Nucleophile, 3 Asp residues

27
Q

sphingolipids

A

long chain amino alcohol backbone with a fatty acid connecter via an amide linkage on C2
polar head is attached by glycosidic or phosphodiester linkage

28
Q

ceramide

A

sphingolipid with 1 amide linked fatty acid on C2
head group is H

29
Q

sphinomyelin

A

sphingosine + phosphocholine at C3
type of phospholipid

30
Q

cerebroside

A

mono-sugar group + sphingosine
found in nerve sheaths
type of glycolipid

31
Q

ganglioside

A

sugars or oligosaccharides + sphingosine
type of glycolipid

32
Q

glycosphingolipids

A

found on outside of plasma membranes for cell-cell recognition, as well as in blood type identification

33
Q

what phospholipid and sphingolipid are structurally similar?

A

phosphatidylcholine and sphingomyelin
both have phosphocholine head

34
Q

blood type is determined by

A

glycosphingolipids. The structure of the sugar is determined by glycosyltransferase and what it transfers:
Type O antigen - no active glycosyltransferase
Type A antigen - transfer of N-acetylgalactosamine
Type B antigen - galactose group
AB is both

35
Q

phospholipase A1
phospholipase A2
phospholipase C
phospholipase D

A

A1: cleaves after O at C1
A2: cleaves after O at C2
C: cleaves before phosphate group (after O at C3)
D: cleaves after phosphate group (before O)

36
Q

biologically active lipids

A

no glycerol or fatty acids
steroids - made from acetate or modification of other sterols
ex. bile salts, hormones
prostaglandins - made from modified fatty acids

37
Q

sterol structure

A

4 fused rings (almost planar, A-D), hydroxyl group off A ring, and non polar side chains
phytosterols - plants
cholesterol - animals
no sterols in bacteria

38
Q

steroid hormones

A

oxidized derivatives of sterols, made from cholesterol in gonads and adrenals
no alkyl hydrophobic chain (and therefore more polar)
carried through blood attached to carrier proteins

39
Q

eicosanoids

A

signaling molecules from oxidized arachadonic acid:
prostaglandins - regulate inflammation and fever
thromboxanes - regulate formation of blood clots
leukotrienes - smooth muscle contraction

40
Q

3 structures lipids aggregate into in water

A

micelles, lipid bilayers, and liposomes
dependent on type of lipid and concentration

41
Q

micelles form with

A

amphipathic molecules with larger polar heads than tails (width, conical shaped)
such as: FFA, detergents, some steroids, lysophospholipids

42
Q

lipid bilayer forms with

A

cylindrical shaped lipids (more than one tail)
such as: phospholipids and sphingolipids
made of 2 leaflet monolayers
stabilized by van der waals, hydrophobic effect and electrostatic interactions

43
Q

liposome

A

vesicle, made of same as lipid bilayer but in a hollow sphere shape
inside sphere is aqueous to store and transport hydrophilic molecules

44
Q

trilaminar membrane permeability

A

impermeable to charged ions and large molecules or proteins
permeable to hydrophobic molecules, neutral gases and small uncharged polar molecules like water

45
Q

uncatalyzed membrane lipid movement
catalyzed membrane lipid movement

A

lateral movement and axis spin
transbilayer movement
flippase - outside to inside flip (ATP dependent)
floppase - inside to outside flip (ATP dependent)
scramblase - either direction towards equilibrium

46
Q

why is it hard for polar molecules to pass through lipid bilayer?

A

because of hydrophobic phospholipid tails on the inside of the membrane

47
Q

outer leaflet is often more

A

positively charged

48
Q

predominant outer layer phospholipids

A

phosphatidylcholine and sphingomyelin

49
Q

predominant inner layer phospholipids

A

phosphatidylethanolamine, phosphatidylserine

50
Q

where are lipids made?

A

made in the ER and move from cis golgi apparatus to trans side for packaging

51
Q

integral/intrinsic membrane proteins

A

firmly associated with the membrane, often spanning both leaflets and contain hydrophobic and hydrophilic regions
can be extracted with strong detergents, change in pH, chelating agent, urea and carbonate

52
Q

Anchored (GPI-linked) membrane proteins

A

linked during regulatory events and can be removed by detergents or phospholipases
GPI is a carbohydrate motif
Also called amphitropic proteins

53
Q

Peripheral (non GPI-linked) membrane proteins

A

weakly associated, easily removed by pH buffers, denaturing agents and chelating agents

54
Q

monotopic/polytopic

A

spans 1 or 2 leaflets

55
Q

membrane phases are and depend on

A

gel - liquid ordered state, individual molecules don’t move, tails are fully extended and densely packed
liquid - liquid disordered state, fluid phase, individual molecules move, tails are randomly oriented and loosely packed
increased heat increases fluidity
naturally more fluid than gel, necessary for cellular function

56
Q

how cholesterol works as a fluidity buffer

A
  • amphipathic molecule, acts a buffer by broadening transition temperature (AKA melting temp)
  • rigid hydrophobic planar rings and hydrophobic flexible branched hydrocarbon tail with a polar hydroxyl head

1) in cold temperatures, cholesterol decreases packing of lower fatty acid tail ends which decreases melting temp
2) in warm temperatures, cholesterol increases packing of upper ends of hydrocarbon tails by immobilizing methylene groups which increases melting temp

57
Q

membrane transition temp graph with and without cholesterol

A

sudden shift from gel to fluid state without cholesterol, gradual shift with cholesterol

58
Q

kind of FA that contribute to a more fluid membrane and health benefits

A

short unsaturated fatty acids
also they are more adaptable to temperatures than saturated fatty acids
saturated fatty acid filled membranes are stiffer and more susceptible to rupture

59
Q

what percentage of membrane proteins are integral vs peripheral

A

70% integral, 30% peripheral

Biochemistry I (12 decks)

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