Lipids: Biosynthesis of Fatty Acids Flashcards
1
Q
Where is 90% of fatty acids found in the body?
A
lipoprotein particles
Ex) HDL and LDL
2
Q
Which type of cells secrete HCl?
A
parietal cells in the stomach
3
Q
Which types of cells secrete pepsinogen which is activated by HCl to pepsin?
A
Chief Cells
4
Q
Where is protein broken down into peptides?
A
in the stomach
5
Q
Where are peptides broken down into amino acids?
A
in the intestines
6
Q
Where are di- and tri-peptides and amino acids absorbed in the intestinal lumen?
A
into Na+ dependent secondary transport
7
Q
Which secretion breaks down carbohydrates in the mouth?
A
salivary a-amylase
8
Q
Which secretion stops the action of salivary amylase?
A
HCl secreted by chief cells
9
Q
Which organ secretes a-amylase?
A
Pancreas
10
Q
Which type of carbohydrates are absorbed?
A
monosaccharides
11
Q
Which type of diffusion moves monosaccharides from the cell to the blood?
A
facilitated diffusion
12
Q
Where does most fat digestion occur?
A
duodenum
13
Q
How does the emulsification of fats help surface area of the hydrophobic lipid?
A
increases surface area
14
Q
Where are bile salts from?
A
liver
15
Q
Emulsified fat globule is broken down by what two secretions to from 2-monoacylglycerol and free fatty acids?
A
Pancreatic lipase & bile salts
16
Q
Emulsified fat globule is broken down into what?
A
2-monoacylglycerol and free fatty acids
17
Q
What are the primary products of dietary lipid degradation in the jejunum?
A
Free Fatty Acids, cholesterol and 2-monoacylglycerol
18
Q
What forms micelles?
A
disk shaped clusters of amphipathic lipids
19
Q
Are mixed micelles soluble or insoluble in aqueous solutions of the intestinal lumen?
A
soluble
20
Q
Which enzyme converts 2-monoacylglycerols to triacylglycerols?
A
mono- and di-acylglycerol acyltransferase
21
Q
Short and medium chain fatty acids do or don’t require mixed micelles for absorption?
A
don’t
22
Q
What are triacylglycerols and cholesteryl esters incorporated into during absorption?
A
chylomicrons
23
Q
How and where are chylomicrons released?
A
released by exocytosis from enterocytes into the lacteals
24
Q
Which body system transports chylomicrons?
A
lymphatic system
25
What is the precursor to hormones?
fatty acids
26
where are fatty acids stored?
adipose tissue
27
how do fatty acids transport in the blood?
by albumins
28
When is there large amounts of fatty acids in the plasma (blood)?
during the fasting stage
29
define amphipathic
a hydrophobic compound with a hydrophilic end
30
Which side of a fatty acid chain predominates?
hydrophobic portion
31
Which type of fatty acid has double bonds?
unsaturated
32
Which type of fatty acid does not have double bonds?
saturated
33
Which type of fatty acid is liquid at room temperature?
unsaturated
34
Which type of fatty acid is solid at room temperature?
saturated
35
Which configuration of an unsaturated fatty acid is synthetic?
trans
36
Which configuration allows loose, pliable membranes?
Cis
37
Which configuration forms stiff membranes?
trans
38
Which type of fatty acid configuration are most preservatives made of?
unsaturated trans
39
What is the common name for a fatty acid with 4 carbons?
Butyric Acid
40
What is the common name for a fatty acid with 10 carbons?
Capric Acid
41
What is the common name for a fatty acid with 16 carbons?
Palmitic Acid
42
What is the common name for a fatty acid with 16 carbons and 1 double bond?
Palmitoleic Acid
43
How many carbons and double bonds des Palmitoleic Acid have?
16:1
44
Which fatty acid has an 18 carbon chain?
Stearic Acid
45
What is the common name for a fatty acid with 18 carbons and 1 double bond?
Oleic Acid
46
How many carbons and double bonds does Oleic Acid have?
18:1
47
What is the common name for a fatty acid with 18 carbons and 2 double bonds?
Linoleic Acid
48
How many carbons and double bonds does linoleic acid have?
18:2
49
What is the common name for the fatty acid with 18 carbons and 3 double bonds?
alpha-linolenic acid
50
How many carbons and double bonds does alpha-linolenic acid have?
18:3
51
What is the common name for a fatty acid with 20 carbons and 4 double bonds?
arachidonic acid
52
How many carbons and double bonds does arachidonic acid have?
20:4
53
What are the 3 parts of a fatty acid structure?
1) Hydrophobic Hydrocarbon chain
2) Terminal Carboxyl Group
3) Long chain fatty acid hydrophobic portion (predominates)
54
What are the 2 versions of dietary essential fatty acids?
1) Linoleic Acid (omega 6)
| 2) Linolenic Acid (omega 3)
55
What is the chemical name for omega 3?
Linolenic
56
What is the chemical name for omega 6?
Linoleic
57
Which dietary fatty acid can metabolize into arachidonic acid
linoleic acid (omega 6)
58
Which dietary essential fatty acid is metabolized into producing PGE3 (prostaglandins)?
Linolenic (omega3)
59
Which foods have omega 6 more abundantly?
corn, sunflowers, oils, grains
60
Which essential fatty acid is most abundant in the average American diet?
omega 6
61
Which essential fatty acid is more commonly supplemented?
omega 3
62
Which prostaglandin is a good anti-inflammatory/anti-spasmodic?
PGE1 and PGE3
63
Which essential fatty acid can produce PGE1?
omega 6
64
What is produced from too much omega 6 consumption?
arachidonic acid
65
If arachidonic acid is produced, what can also possibly be produced?
PGE2
66
Which prostaglandins is a pro-inflammatory marker?
PGE2
67
Which essential fatty acid is most often supplemented?
omega 3
68
Where can omega 3 be found?
veggie/ greens
69
Which essential fatty acid inhibits arachadonic acid?
omega 3
70
How is VLDL assembled?
from cholesterol and apolipoproteins
71
What does VLDL transport?
endogenous products
72
What does VLDL convert to in the bloodstream?
LDL
73
What does chylomicrons transport?
exogenous products
74
What is the key marker formation for LDLs?
atherogenic
75
Where does the synthesis of fatty acid occur?
liver and lactating mammary glands
76
When does fatty acid synthesis occur?
Well Fed state
77
What is the main building block of fatty acids?
Acetyl CoA
78
Where does fatty acid synthesis occur in the cell?
cytosol
79
Where is Acetyl CoA produced?
kreb cycle
80
How do you get Acetyl CoA out of the mitochondria?
cleave the CoA because its too bulky
81
List the process of how AcetylCoA leaves the mitochondria
1) Acetyl CoA + OAA + citrate synthase -(CoA) = Citrate
2) Citrate transport
3) CoA + ATP Citrate Lyase ---> Oxyloacetate + AcetylCoA
82
Which two enzymes are involved with converting/breaking down citrate from AcetylCoA and Oxaloacetate?
Citrate Synthase
| ATP Citrate Lyase
83
Which enzyme cleaves Citrate as it leaves the cell?
ATP-Citrate Lyase
84
What allosterically activates Acetyl CoA Carboxylase?
High Citrate
OR
Low amounts of long-chain fatty acids
85
What allosterically inhibits Acetyl CoA Carboxylase?
Long Chain Fatty AcylCoA
86
Which enzyme converts AcetylCoA to MalonylCoA?
AcetylCoA Carboxylase
87
Prolonged consumption of excess calories causes an increase the synthesis of which enzyme?
AcetylCoA Carboxylase
88
What is the name of a multicatalytic polypeptide with seven different enzymatic activities plus a domain
Fatty Acid Synthase Monomer
89
What is the first step of fatty acid synthesis?
Acetate is transferred from acetyl CoA to the SH grouo of the acyl carrier protein (ACP) using the enzyme acetyl-CoA ACP transacylase
90
What happens to the 2-carbon fragment left from the first step of fatty acid synthesis?
transferred to a temporary holding site B-ketoacyl-ACP synthase
(SH of the cysteine residue)
91
Which enzyme combines ACP and Acetyl CoA?
acetyl-CoA ACP transacylase
92
What is the condensing enzyme to help form Acetoaceyl-ACP
B-ketoacyl-ACP synthase
93
What are HDLs? What does it transfer/do?
High-Density Lipoprotein, richer in protein
| Transfer fats from the adipose tissue to the liver to be oxidized and broken down
94
What are LDLs? What do they transfer/do?
Low-Density Lipoprotein
| responsible for binding fats at the liver and sending them to the adipose tissue to be stored?
95
What is the name for a 16 carbon saturated fatty acid?
Palmitate/ Palmitic Acid
96
Allosteric Activation of which enzyme Converts AcetylCoA to MalanylCoA?
AcetylCoA Carboxylase
97
What initiates Fatty Acid synthesis?
Allosteric Activation of AcetylCoA Carboxylase?
98
How can you shut down AcetylCoA Carboxylase (inactiveate)?
Protein Kinase A (adds a phosphate)
99
What activates protein phosphatase?
High concentration of insulin and fructose 6
100
What removes a phosphate from AcetylCoA Carboxylase and then in turn, activates it??
Protein Phosphatase
101
What activates protein kinase A?
AMPK AND Glucagon/epinephrine
102
Fatty Acid synthesis is how many reactions?
7
103
What does ACP replace ?
CoA
104
What is a component of Vitamin A, derived from pantothenic acid, and is the domain that binds a fatty acid synthase monomer?
4'phosphopantetheine
105
What is the 4 carbon molecule formed by the Acetyl-ACP and Malonyl-ACP
Acetoacetyl-ACP
106
To react with the more accessible ketone on Acetoacetyl-ACP, which enzyme is used and what is formed?
enzyme: beta-ketoacyl-ACP reductase + NADPH
molecule: beta-hydroxybutyryl-ACP
107
To remove the newly created alcohol group off of Beta-hydroxybutyryl-ACP, which enzyme is used and what is formed?
Beta-hydroxyacyl-ACP dehydrase (-H2O)
Molecule: alpha, beta-trans-Butenoyl-ACP
108
Why does the trans molecular position help the synthesis of fatty acid?
trans prevents breaking down while making
109
Which enzyme is repeatedly used to reduce a hydroxy group to a fat chain?
Beta-hydroxyacyl-ACP dehydrase (-H2O)
110
What are the 3 enzymes used in fatty acid synthesis?
beta-ketoacyl-ACP Synthase
beta-ketoacyl-ACP reductase
beta-hydroxyacyl-ACP dehydrase
111
Which enzyme is used to reduce the double bond from a fat?
enoyl-ACP reductase
112
How many cycles occur after Butyryl-ACP is formed during fatty acid synthesis?
6 more times
113
Which enzyme cleaves the ACP to stop the adding of carbons onto the building fatty acid chain?
palmitoyl thioesterase
114
How many carbons are on the final Palmitate fatty acid chain?
16 carbons
115
How many carbons are added with each cycle of fatty acid biosynthesis?
2 carbons each cycle
116
What is the final 16 carbon fatty acid?
palmitate
117
How many fatty acid chains make up a triacylglycerols?
3 chains
118
Which fatty acid chain on a triacylglycerol is saturated?
1 (possibly 3)
119
Which fatty acid chain on a triacylglycerol is unsaturated?
2 (possible 3)
120
Why is 2nd carbon fatty acid chain unsaturated?
decreases the melting temperature of the lipid
121
What is the initial acceptor of the fatty acid during triacylglycerol synthesis?
Glycerol Phosphate
122
Where is triacylglycerol primarily synthesized?
Liver
123
When can adipocytes take up glucose?
ONLY in the presence of insulin
124
How is a fatty acid converted into its active form?
(attached coenzyme A) before it can participate in TAG synthesis
125
How many reactions to form a TAG?
4 reactions
126
Which enzymes convert Glycerol Phosphate to a TAG?
Acyltransferase (3x)
| Phosphatase(1x)
127
Which enzyme removes a phosphate to help react by adding a fat?
Phosphatase
128
What are the 5 molecules involved in TAG synthesis?
1) Glycerol Phosphate
2) Lysophosphatidic Acid
3) Phosphatidic Acid
4) Diacylglycerol
5) TAG
129
Where is TAG stored?
cytosol of the adipose cells
130
Why do you want the 1 carbon fatty acid on a TAG to be saturated?
Yields more energy
131
Where can you find Glycerol kinase?
ONLY in liver
132
What two molecules do you need to start making a TAG?
Glycerol molecule and a Fat
133
How can you get glycerol molecule and a fat to react together to activate forming a TAG?
Put energy into the reaction using glycerol kinase plus an ATP
134
Which enzyme helps the 1st step of activating TAG synthesis?
Glycerol Kinase
135
which molecule is the only one that is active when it's phosphorylated?
Hormone-Sensitive Lipase
136
How many AcetylCoA are used in fatty acid synthesis?
8
137
How many NADPH to make palmitate in fatty acid synthesis?
14
138
How many ATP are used to make palmitate in fatty acid synthesis?
7
139
How are fats transferred from the liver to fat storage?
3 fats and a glycerol molecule are turned into triacylglycerol, binds to VLDL/LDL, sent to the periphery
140
Which enzyme aids with the absorption of fats into adipose tissue?
lipoprotein lipase
141
What does hormone sensitive lipase do in the fasting state?
Protein Kinase A activates HSL by phosphorylating it, fats start secreting from adipose tissue, mobilize fats and send them through the system
142
How is hormone sensitive lipase dephosphorylated (made inactive)?
High levels of insulin and glucose
