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biochem > biochem lecture 8 pt 1 > Flashcards

biochem lecture 8 pt 1 Flashcards

1
Q

what is lipid catabolism

A

how lipids are used as an E source

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2
Q

major functions of fatty acids

A

formation of cell membranes, role in energy metabolism

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3
Q

major component of lipids

A

fatty acids

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4
Q

what are fatty acids

A

long chains of hydrocarbons

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5
Q

2 types of fatty acids

A

saturated and unsaturated

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6
Q

saturated fatty acids

A

C-C bonds are all single bonds

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7
Q

unsaturated fatty acids

A

one or more double bond (C=C)

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8
Q

what are fatty acids

A

hydrocarbon chains; made up excluisvely of Cs and Hs. C-C bonds form backbones, Hs bonded to Cs

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9
Q

what does double bond present in unsaturated fat cause

A

causes it to bend or kink

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10
Q

what can kinking affect

A

membrane fluidity

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11
Q

most abundant dietary lipids

A

triglycerides

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12
Q

where are triglycerides found

A

animal and plant foods

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13
Q

what are triglycerides referred to

A

neutral fat/lipid (cuz its uncharged)

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14
Q

why are triglycerides neutral fat

A

because they are uncharged

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15
Q

what are triglycerides structure

A

glycerol backbone (3 C structure), 3 fatty acids attached to backbone via ester linkages

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16
Q

what is an “essential” compound

A

something an organism cannot synthesize on its own; requires it from exogenous source

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17
Q

2 essential fatty acids

A

linoleic and linolenic acid

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18
Q

can we synthesize linoleic and linolenic acid on our own

A

nope; need them from outside sources

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19
Q

where do we primarily get linoleic and linolenic acid

A

from vegetable sources

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20
Q

what are adipocytes

A

fatty acids/fats that deposit in certain parts of the body/ specific kinda cell

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21
Q

what kinda tissue due adipocytes form

A

adipose tissue

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22
Q

functions of adipose tissue

A

protective cushion around body organs, insulating function underneath skin, highly concentrated store of E

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23
Q

roles of dietary fats

A

E metabolism, E source, cell membranes

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24
Q

another function of lipids

A

can be metabolites of lipids; bioactive compounds

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25
Q

example of bioactive lipid

A

prostaglandin

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26
Q

what are prostaglandins important in

A

regulation of blood pressure, activation of inflammatory responses, smooth muscle contraction

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27
Q

another important lipid

A

cholesterol

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28
Q

functions of cholsterol

A

regulates membrane fluidity, precursor of synthesis of molecules like bile salts, steroid hormones

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29
Q

importance of liver in glucose metabolism

A

major storage site for glycogen. hormones that regulate catabolic and anabolic glycogen pathways are in liver. basically, liver is important for distribution & storage of carbs

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30
Q

how is liver important for lipid metabolism

A

important for synthesis of lipoproteins, can synthesize clotting factors, and is where cholesterol biosynthesis occurs.

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31
Q

what are lipoproteins

A

proteins w/ lipids, important for transport of cholesterol and fats

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32
Q

what is precursor for cholesterol biosynthesis

A

acetyl CoA

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33
Q

what is cholesterol a precursor of

A

synthesis of bile salts, steroid hormones like estrogen, progesterone, testosterone

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34
Q

two main functions of lipids

A

membrane lipids, energy storage form

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35
Q

diff types of membrane lipids

A

phospholipids, glycolipids, archaeobacterial ether lipids

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36
Q

are membrane lipids polar or nonpolar

A

polar

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37
Q

what are two categories of lipids

A

membrane and storage lipids

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38
Q

what are phospholipids

A

major type of membrane lipids we find in cells

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39
Q

what are what we generally call phospholipids

A

glycerol phospholipids

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40
Q

describe structure of glycerol phospholipids

A

three carbon glycerol backbone; ester bonds attaching fatty acids at first 2 positions, and phosphate group on C3, on which is a polar head group (alcohol, etc.)

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41
Q

what are sphingolipids

A

sphingosine backbone; found in membranes, covering of nerve tissue, myelin sheaths, etc.

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42
Q

what lipids are we primarily focusing on

A

energy storage lipids –> triglycerides

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43
Q

what else are triglycerides known as

A

storage lipids or neutral lipids

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44
Q

describe structure of triglycerides

A

3 C glycerol backbone; fatty acids attached to all 3 positions on glycerol backbone via esterification

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45
Q

why do we call triglycerides neutral lipids

A

because they have 3 fatty acids attached, not 2 fatty acids and polar head group

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46
Q

what kinda molecules are phospholipids

A

amphipathic

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47
Q

why are phospholipids amphipathic

A

cuz they have both polar and nonpolar parts (polar head group)

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48
Q

what are neutral lipids

A

glycerol backbone w/ 3 fatty acids attached

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49
Q

what is glycerol

A

a triol

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50
Q

what is triol

A

3 carbon alcohol

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51
Q

describe triglyceride structure

A

fatty acids linked to glycerol via ester bonds

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52
Q

are glycerol and fatty acids metabolized in the same ways

A

nope; different ways

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53
Q

how do we get triglycerides

A

we can synthesize them or ingest from diet

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54
Q

what kinda bonds in triglycerides

A

ester bond

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55
Q

what kinda bond is ester bond

A

covalent bond that joins fatty acids to glycerol backbone

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56
Q

do glycerol and fatty acids have same or diff pathways

A

diff pathways

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57
Q

what processes occur in cytosol

A

glycolysis, pentose phosphate pathway, fatty acid synthesis

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58
Q

what happens in mitochondrial matrix

A

cTCA, ox phos, b-oxidation of fatty acids, ketone body formation

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59
Q

what is an interplay of both cytosolic and mitochondrial compartments

A

gluconeogenesis, urea synthesis

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60
Q

where does synthesis of fats occur

A

in cytosol

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61
Q

what 3 ways do cells obtain fatty acid fules

A

diet, fats stored in cells as lipid droplets, fats synthesized in liver for export to other organs

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62
Q

where are fats stored in lipid droplets

A

adipocytes/adipose tissue

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63
Q

what kinda molecules are fats

A

hydrophobic nonpolar molecules

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64
Q

what is needed for fats to be distributed/transported to tissues to undergo breakdown/catabolic processes

A

need to be transported into chylomicrons

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65
Q

what are chylomicrons

A

allow for nonpolar fat molecules to travel thru otherwise polar aqueous environment (blood)

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66
Q

how are most products of fat metabolism transported in lymph as

A

as chylomicrons

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67
Q

what happens when chylomicrons are delivered to the specific tissue

A

undergo metabolic processing; hydrolytic enzymes will break them down

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68
Q

what does process of hydrolyzing triglycerides entail

A

separating fatty acids from glycerol backbone

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69
Q

where are hydrolytic enzymes found

A

some in blood, some intracellular

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70
Q

what 2 pathways are in catabolism of fats

A

glycerol pathway, fatty acid pathway

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71
Q

before we talk about pathways, what do we need to address

A

how dietary lipids are processed

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72
Q

what happens when we ingest fats from our diet

A

lipids pass thru stomach, small intestine

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73
Q

where are bile salts stored

A

gallbladder

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74
Q

what happens to bile salts when we eat food w/ lots of fats

A

bile salts will be released from gallblader thru a duct system, into duodenum/upper portion of small intestine (bile salts, gallbladder–> small intestine)

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75
Q

what process do bile salts carry out

A

emulsification

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76
Q

what is emulsification

A

separation of triglycerides from each other

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77
Q

does emulsification break covalent bonds

A

nope, just separate triglycerides

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78
Q

what comes after bile salts do emulsification

A

intestinal lipases

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79
Q

what are lipases

A

hydrolytic enzymes; cleaves or separates fatty acids from glycerol backbone

80
Q

what do intestinal lipases do

A

degrade the triglycerides

81
Q

what are we left with after intestinal lipases do their jobs

A

individual fatty acids and glycerol backbone

82
Q

what is next step after intestinal lipases

A

absorption of individual fatty acids and glycerol into intestinal mucosa

83
Q

what is important for absorption of individual fatty acids

A

lipoproteins; specific transport systems involving lipoproteins

84
Q

what happens once these individual fatty acids (derived from triglycerides) are absorbed into intestinal mucosal cells

A

reassembled into triglycerides

85
Q

what happens to triglycerides when procesed

A

degradation and then reassembly

86
Q

why is degradation and reassembly necessary

A

important for enabling fatty acids to be more efficiently absorbed into intestinal mucosa

87
Q

what happens to reassembled triglycerides

A

packaged into a structure called chylomicron

88
Q

what are chylomicrons made of

A

combo of triglycerides, cholesterol, apolipoproteins, other lipids

89
Q

what is the goal of chylomicrons

A

to transport fatty acids in form of triglycerides that are housed within chylomicron to the target organs (where they will be used as energy

90
Q

what happens to fatty acids at target organs

A

will be used as energy

91
Q

what is goal of chylomicron

A

to transport fatty acids (in triglyceride form) to target, where it can be used as energy

92
Q

what are chylomicrons

A

what we store lipids in as they are being transported throughout bloodstream in body

93
Q

what are 2 possibilities where we have fatty acid metabolism going on

A

muscle, adipocytes

94
Q

what happens in muscle

A

major site where b-oxidation of fats takes place

95
Q

what happens in adipocytes

A

adipose tissue is where we store triglycerides; can be processed and go thru beta-oxidation in muscles

96
Q

describe where fats are stored and used

A

we can store them in adipose tissue; if muscle requires E, some triglycerides can be processed, fatty acids oxidized thru b-oxidation in muscles

97
Q

then what do chylomicrons do

A

transport fatty acids to target tissues

98
Q

what happens to triglycerides once they reach target tissue

A

undergo further processing

99
Q

what is lipoprotein lipase

A

does the same thing as intestinal lipase

100
Q

what do lipoprotein lipase do to chylomicrons

A

break htme down to individual fatty acids

101
Q

what happens to individual fatty acids broken down by chylomicrons

A

absorbed into myocytes/adipocytes, where they can be oxidized/stored

102
Q

what happens to fatty acids in myocites

A

undergo oxidation

103
Q

what happens to fatty acids in adipocytes

A

stored in fat droplets

104
Q

describe chylomicron structure

A

phospholipid surface, polar head groups facing outward

105
Q

where do polar head groups face in chylomicrons

A

face outward

106
Q

what makes up chylomicrons

A

major composition is triglycerides

107
Q

what part of chylomicrons do triglycerides make up

A

80% of mass

108
Q

what other lipids in chylomicron

A

phospholipids, etc.

109
Q

where is phospholipids on chylomicron

A

form exterior layer

110
Q

what is present on surface of chylomicron

A

apolipoproteins

111
Q

function of apolipoproteins

A

trigger activation of some lipases

112
Q

example of apolipoproteins activating lipases

A

lipoprotein lipases being triggered one chylomicron reaches destination

113
Q

what are main functions of apolipoproteins

A

binding to specific cell surfaces, and activating lipases

114
Q

what happens to triglycerides once they’ve been reassembled in target tissues

A

if in muscle tissue (where we’re gonna oxidize fatty acids and glycerol to generate ATP E), two separate pathways

115
Q

what does glycerol undergo

A

converted to GAP I(in short multi step pathway), GAP converted to acetyl CoA, acetyl CoA goes to krebs cycle

116
Q

what happens to the GAP

A

fed into glycolysis, converted into acetyl CoA

117
Q

what happens to acetyl CoA

A

into TCA cycle, carbons get completely oxidized

118
Q

what convergence do we see w/ glycerol

A

convergence of glycerol pathway thru formation of GAP in glycolysis pathway

119
Q

what pathway for fatty acids

A

beta-oxidization pathway

120
Q

what do we get after fatty acids go thru b-oxidation

A

two carbon acetate fragments (from fatty acids, long chain hydrocarbons)

121
Q

what happens to those 2 carbon acetate fragments

A

joined w/ coenzyme A to generate acetyl CoA

122
Q

what happens to acetyl CoA

A

enter TCA cycle, carbons undergo complete oxidation

123
Q

where does term B-oxidation come from

A

from the fact that we generate two carbon fragments; indicates where cleavage rxns are gonna cocur

124
Q

what can be genrated from oxidation of fats

A

substantial amount of reducing power

125
Q

what can we get from acetyl CoA

A

lot of PE, lot of NADH and FADH2

126
Q

why can we get a lot of NADH, FADH2

A

because each of those acetyl CoA units can enter TCA cycle and generate a lot of NADH, FADH2

127
Q

what happens when triglycerides get degraded

A

individual fatty acids have been separated from glycerol backbone

128
Q

what happens to individual fatty acids

A

beta-oxidation pathway

129
Q

what happens to glycerol

A

glycerol pathway

130
Q

how many steps in glycerol pathway

A

3 steps

131
Q

what happens in glycerol pathway

A

glycerol is converted to glyceraldehyde-3-phosphate (GAP)

132
Q

what is first step of glycerol pathway

A

glycerol –> glycerol-3-phosphate

133
Q

what enzyme for step 1 of glycerol pathway

A

glycerol kinase

134
Q

what is second step of glycerol pathway

A

glycerol-3-phosphate –> dihydroxyacetone phosphate (DHAP)

135
Q

what enzyme for second step

A

glycerol-3-phosphate dehydrogenase

136
Q

what does glycerol-3-phosphate do

A

generates some reducing power

137
Q

what is DHAP

A

glycolysis intermediate; metabolically a dead end

138
Q

can DHAP undergo further processing

A

nope

139
Q

what do we need to do to DHAP

A

convert it to GAP

140
Q

what is step 3 of glycerol pathway

A

dihydroxyacetone phosphate (DHAP) –> glyceraldehyde-3-phosphate (GAP)

141
Q

what enzyme in step 3 of glycerol pathway

A

triose phosphate isomerase

142
Q

is there an energy investment? where

A

yes, step 1

143
Q

why does it not matter that we used ATP

A

cuz we will harvest E thru substrate level phosphorylation in glycolysis, and more from reducing power in TCA cycle

144
Q

what do lipases do

A

hydrolyze triglycerides; get fatty acids and glycerol

145
Q

what happens to fatty acids

A

form acetyl CoA (thru beta oxidation), go into TCA

146
Q

what happens to glycerol

A

glycerol pathway

147
Q

sum yp glycerol pathway

A

glycerol is phosphorylated to glycerol-3-phosphate. glycerol-3-phosphate is oxidized to DHAP. DHAP is isomerized to GAP

148
Q

what happens to GAP

A

enters glycolysis

149
Q

what is end product of glycerol pathway and what happens to it

A

glyceraldehyde-3-phosphate; goes into glycolysis

150
Q

what happens to GAP after glcyolysis

A

converted to pyruvic acid

151
Q

what happens to pyruvic acid at end of glycolysis

A

converted to acetyl CoA

152
Q

where does acetyl CoA go

A

TCA

153
Q

what is end product of beta oxidation of fatty acids

A

acetyl CoA

154
Q

what happens to acetyl CoA

A

goes into TCA cycle

155
Q

what is generated in steps where fatty acids converted to acetyl CoA

A

little bit of reducing power

156
Q

another word for beta oxidation of fatty acids

A

fatty acid breakdown (catabolism)

157
Q

what 3 steps are required for fatty acid breakdown

A

mobilization, activation & transport, breakdown or beta oxidation

158
Q

what is first overall step in beta oxidation

A

mobilization. triglycerols degraded into fatty acids and glycerol, subsequently released from adipose tissue into E-requiring tissues.

159
Q

what is mobilization step

A

lipases degrade triglycerides into 2 main components: glycerol backbone, fatty acids. if in adipocytes, glycerol & fatty acids are gonna be released and transferred to tissues that need E (like muscle and liver)

160
Q

what happens after mobilization step, after fatty acids are absorbed into tissues that require E

A

need to undergo an activation step, and transportation into mitochondria

161
Q

what happens once fatty acids are in mitochondrial matrix

A

undergo step 3, beta oxidation

162
Q

where does beta oxidation occur

A

mitochondrial matrix

163
Q

what is beta oxidation

A

breakdown of fatty acids

164
Q

what regulates mobilization of triglycerides

A

insulin and glucagon

165
Q

where else were insulin and glucagon

A

carbon metabolism

166
Q

what are both epinephrine and glucagon

A

GPCRs

167
Q

what do epinephrine and glucagon do

A

activate adenylyl cyclase

168
Q

what does adenylyl cyclase do

A

converts ATP to cAMP

169
Q

what does cAMP do

A

activates PKA

170
Q

what does PKA activate

A

triacylglycerol lipase

171
Q

what does triacylgycerol lipase do

A

responsible for hydrolysis/release of fatty acids from glycerol backbone of triglycerides

172
Q

what happens once fatty acids released from glycerol backbone

A

gonna be exported from adipocyte to tissues who need E

173
Q

what do we have in adipocytes

A

lipid droplets or concentrations of tryglycerides

174
Q

what do triglyceride metabolism and glycogen breakdown/synthesis have in common

A

same hormones

175
Q

what happens in low blood glucose conditions

A

we will release of glucagon

176
Q

what does glucagon do

A

activates pathway in previous slide (cAMP –> PKA)

177
Q

what does PKA do

A

activates hormone sensitive lipase

178
Q

what does PKA do in adipocytes

A

phosphorylates a protein called perilipin

179
Q

where is perilipin

A

situated on the surface of lipid droplets

180
Q

basically what happens when glucagon activates PKA

A

2 things: PKA phosphorylates and activates hormone sensitive lipase, and will phosphorylate perilipin protein on surface of lipid droplet

181
Q

what does phosphorylating perilipin do

A

increases accessibility of those triglycerides to hormone sensitive lipase; makes triglycerides more accessible to hormone sensitive lipase

182
Q

what does hormone sensitive lipase do

A

hydrolysis of ester bonds that release fatty acids from glycerol backbone

183
Q

what happens after lipases breakdown tryglicerides

A

we get transport of fatty acids in bloodstream

184
Q

how are fatty acids being transported thru blood

A

serum proteins that can bind to fatty acids; specific lipid binding proteins that can cover and transport hydrophobic lipids

185
Q

why doesn’t this transport involve chylomicrons

A

cuz chylomicrons are in processing of dietary lipids, not mobilization

186
Q

what do serum proteins do

A

glom onto fatty acids, transport them

187
Q

where are fatty acids going

A

to myocyte; to be fully utilized by b-oxidation

188
Q

example of serum protein

A

albumin

189
Q

what do serum proteins do

A

bind to fatty acids, important for their transport thru bloodstream

190
Q

basically sum up mobilizatoin

A

mobilize triglycerides from fat stores in adipose tissue, transport fatty acids where they can be taken up into myocytes into muscle cells for beta oxidation

191
Q

what do hormone sensitive lipases do

A

cleave these ester linkages

192
Q

what are gonna be products of hormone sensitive lipases

A

individual fatty acids, glycerol backbone

193
Q

why are they called hormone sensitive lipases

A

because pathways are activated by these hormones

194
Q

what effect do insulin and glucagon have on these lipases

A

opposing effects

195
Q

what does insulin do to hormone sensitive lipase

A

inactivates lipase

196
Q

what does glucagon do to hormone sensitive lipase

A

activates it

197
Q

sum up overall effects of these lipases in presence of hormones

A

inhibitory in presence of insulin, stimulatory in presence of glucagon

biochem (15 decks)

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