Lipids, Beta Oxidation, lipid syntesis (complete) Flashcards
(166 cards)
1
Q
What are some biological functions of lipids
A
- STORAGE OF ENERGY
- Insulation
- Water repellant
- Buoyancy
- MEMBRANE STRUCTURE
- cofactors for enzymes
- SIGNALING MOLECULES
- Pigments
- Antioxidants
2
Q
What makes Lipids effecient at storing energy
A
- they are reduced compounds (lots of available energy)
2. their hydrophobic nature (Good for tight packing)
3
Q
What role do lipids play in membrane structure
A
they are the main structure of cell membranes
4
Q
What signaling molecules are made of lipids
A
- paracrine hormones
- steroid hormones
- Growth factors
- Vitamins A + D
5
Q
What determines if a fatty acid is an Omega 3 (or Omega 6) fatty acid
A
Omega 3 fatty acids are fatty acids that have a double bond that begins on the third Carbon counting from the back of the fatty acid.
(Omega 6 are fatty acids that have a double bond that begins on the 6th carbon from the back)
6
Q
Do humans Synthesize omega 3 fatty acids
A
nope
7
Q
Do humans need omega 3 fatty acids
A
yes
8
Q
is omega 3 an essential nutrient
A
yes
9
Q
How is the solubility of a fatty acid affected by its chain length
A
the longer the chain the less soluble it becomes
10
Q
how is the melting point of a fatty acid affected by its chain length
A
the longer the chain the higher the melting point
11
Q
how is the melting point of a fatty acid affected by the number of double bond it has
A
the more double bonds a fatty acid has the lower the melting point
12
Q
Which type of fatty acid will be the least soluble
A
a long one
13
Q
which type of fatty acid will have the highest melting point
A
the longest fatty acid with the least number of double bonds
14
Q
Which type of fatty acid will have the lowest melting point
A
a short fatty acid with many double bonds
15
Q
What is a saturated fatty acid
A
a fatty acid without double bonds
16
Q
what is an unsaturated fatty acid
A
a fatty acid with double bonds
17
Q
What is a monounsaturated fatty acid
A
a fatty acid with one double bond
18
Q
what is a polyunsaturated fatty acid
A
a fatty acid with multiple double bonds
19
Q
What are the steps in naming a fatty acid
A
A:B (DeltaC,C,C) D-C- Name
A = Number of carbons in the fatty acid
B = The Number of double bonds in the fatty acid
C = The different Carbon #’s that start a double bond
D = whether the C double bond is cis or trans
20
Q
18:1 (Delta 9) cis-9- (NAME)
how many carbons does this fatty acid have
A
18
21
Q
18:1 (Delta 9) cis-9- (NAME)
how many double bonds does this fatty acid have
A
1
22
Q
18:1 (Delta 9) cis-9- (NAME)
where does the double bond of this fatty acid begin
A
the 9th carbon
23
Q
18:1 (Delta 9) cis-9- (NAME)
is the double bond in this fatty acid cis or trans
A
cis
24
Q
Which type of bond is more common in natural unsaturated fats
A
Cis
25
What does the Cis double bond lead to in the fatty acid chain
a kink in the chain
26
Which fats pack and stack better: unsaturated or saturated fats
saturated fats
27
why don't unsaturated fats pack and stack as well as saturated fats
because their double bond puts a kink in the chain
28
Which type of fatty acids have a higher melting point: saturated or unsaturated fatty acids
saturated fats
29
why do saturated fats have a higher melting point than unsaturated fats
because saturated fatty acids are straight and stack better, so the have greater van der waal forces between them, making them harder to pull apart.
30
What is a trans fatty acid
unsaturated fatty acids that are partially dehydrogenated. this gives it a trans double bond instead of a cis double bond
31
what does a trans double bond do to the fatty acid
makes it more extended (less kinked) which gives it a higher melting point
32
why are trans fats made
it increases the shelf life
| it has a higher melting point (solid at room temp)
33
What is the problem with trans fats
consuming them increases the risk of cardiovascular disease
34
What does the basis of lipid classification come from
the structure and function of the lipid
35
Do all lipids contain fatty acids
nope
36
What is an example of lipids that don't have fatty acids
cholesterol
37
What are the two different classifications of lipids that DO have fatty acids
storage lipids and membrane lipids
38
What is the name for the type of lipids that are storage lipids
triacylglycerols
39
What are the different categories of membrane lipids
1. phospholipids
2. glycolipids
3. archaebacterial ether lipids
40
What is the structure of triacylglcerols
a glycerol bound to three fatty acids
41
Are triacylglycerols polar or nonpolar
nonpolar
42
Why do fats carry more energy per carbon than polysaccharides
because they are more reduced
43
Which is for quick delivery of energy? fatty acids or polysaccharides
polysaccharides
44
What makes up glycerophospholipids
1. Glycerol (3 binding sites)
2. Two attached Fatty acids bound to glycerol
3. a phosphate that can have an alcohol added to it
45
What kind of fatty acid is usually added to the C2 of a glycerophospholipid
a UNsaturated fatty acid
46
A glycerophospholipid usually has two fatty acids (C2 usually has an unsaturated fatty acid), what else is bound to it
a phosphate group
47
what is usually added to the phosphate group of a glycerophospholipid
an alcohol
48
What is the name for substituent groups added onto the glycerol that aren't fatty acids
head groups
49
Where is phosphatidylcholine used
it is the major component of most eukaryotic cell membranes
50
What is phosphatidylcholine
a glycerophospholipid with a choline as the head group
51
What is phosphatidylethanolamine
a glycerophospholipid that has ethanolamine (C2,N,H3) as the head group
52
Is plasmalogen an ether lipid?
yes
53
what is the structure of plasmalogen like in comparison to phosphatidylethanolamine
plasmalogen is the vinyl ether analog of phosphatidylethanolamine. The glycerol has an ether attached to one of it's carbons as opposed to an ester like normal
54
Where is plasmalogen commonly found
heart tissue of vertebrates
55
how well is the function of plasmalogen understood
it is not well understood.
56
how easily is plasmalogen cleaved
not very easily, it is resistant to cleavage by common enzymes, but a few specific lipases can
57
What MAY be some possible functions of plasmalogen
1. increase membrane rigidity
2. source of signaling lipids
3. antioxidants
58
What is the difference between sphingolipids and glycerophospholipids
the backbone of sphingolipids isn't glycerol, its sphingosine
59
What are the main differences between sphingosine and glycerol
1. sphingosine only has two spots where things can bind (it has a long-chain amino alcohol instead of a third space for binding)
2. the fatty acid is joined by amide linkage, not ester linkage
60
What king of fat is sphingomyelin
a sphingolipid
61
What is the structure of sphingomylin like
1. a sphingosine
2. amide linked fatty acid
3. phosphocholine head group
62
Where do we find sphingomyelin
in the myelin sheath that surrounds some nerve cells
63
Why do fats carry less water than polysaccharides
because they are non-polar
64
When do we use glycogen and glucose as energy sources
in short term energy needs, with a quick delivery
65
Are fats for long term storage or short
long term
66
is the delivery of fats into energy fast or slow
it is a slow delivery
67
Where is cholesterol synthesized or obtained from food
the liver
68
from what do many hormones come
sterols
69
What are the steps of digestion of dietary fatty acids from arrival in the intestines to arrival at the tissues
1. Bile salts emulsify dietary fats in the small intestine
2. lipases degrade triacylglycerides
3. break down products are taken up by the intestinal mucosa and converted into triacylglycerols
4. Triacyglycerols, apolipoproteins, and cholesterol are packaged as chylomicrons
5. chylomicrons move through the lymph and blood to the tissues
6. in the capillary lipoprotein lipase converts triacylglycerols into glycerol and fatty acids
7. Fatty acids enter cells and are either used for fuel, or saved as storage
70
What initially emulsifies fats in the small intestine
bile salts
71
what happens to triacyglycerides in the intestine
they are degraded by lipases
72
what happens to the degraded triacyglycerides that are degraded in the intestine once they are moved into the intestinal mucosa
they are reconverted into triacyglycerols
73
What is a chylomicron, and what is its function
it is a ball of fats essentially, with phospholipids making an outer membrane, triacyglycerols and other fatty acids in the middle. and apolipoproteins helping stabilize it.
its function is a sort of transport vesicle for fats through the blood
74
What happens to triacyglycerols in the capillaries
they are broken down by lipoprotein lipase into fatty acids and glycerol so they can enter cells
75
what happens to the fatty acids and glycerol upon arriving at the cell
they are either used for energy or stored
76
What hormone stimulate the breakdown of fats
epinepherine and glucagon
77
what is the difference in signals sent to the fats by epinepherine and glucagon
epinepherine says "we need energy now"
| glucagon says "we are out of glucose"
78
What is the process by which glucagon stimulates the mobilization of stored triacyglycerols
1. glucagon binds to the receptor
2. adenylate cyclase is activated
3. Adenylate cyclase produces cAMP
4. cAMP activates PKA
5. PKA activates Hormone sensitive lipase and phosphorylates perilipin
6. Phosphorylated perilipin causes CGI to move to ATGL
7. ATGL takes triaccylglylcerols and converts them into diacyglycerols
8. Hormone sensitive lipase takes Diacyglycerols and converts them into monoacyglycerols
9. MGL takes monoacyglycerols and cleaves them into glycerol and a fatty acid
10. Fatty acids move to the blood and are transported by serum albumin
11. They enter cells through fatty acid transporters
12. Then begin beta oxidation
79
What are the steps of mobilization of fats from glucagon binding to its receptor, to the first fatty acid chain being removed
1. glucaon binds to the receptor, activating adenylate cyclase
2. adenylate cyclase produces cAMP
3. cAMP activates PKA
4. PKA phosphorylates perilipin, and Hormone sensitive lipase (HSL)
5. Perilipin releases CGI which goes and binds to ATGL
6. ATGL begins to break down triacylglycerols
80
What does ATGL stand for
adipose triacylglycerol lipase
81
what are the steps of fat mobilization from the activation of ATGL by CGI to beta oxidation
1. ATGL breaks down triacylglycerols to diacylglycerols
2. HSL breaksdown diacyglycerols into monoacyglycerols
3. MGL breaks down monoacyglycerols into glycerol and a fatty acid
4. fatty acids are transported in the blood by serum albumin
5. fatty acids leave the blood through fatty acid transporters
6. in the cell they undergo beta oxidation
82
What is MGL
monoacylglycerol lipase
83
what happens to the glycerol that is cleaved off of the monoacyglycerol by MGL
in the cell it is converted into an intermediate of glycolysis and is used to produce ATP
84
What is the enzyme that begins the conversion of glycerol into glyceraldehyde-3-phosphate (intermediate in glycolysis)
glycerol kinase (this step uses ATP)
85
What is the first step of breaking down fatty acids. This happens once it enters the cell
it is converted into fatty acyl-CoA
86
Why are fatty acids converted into fatty acyl-CoA upon entering the cell
So they can be transported into the mitochondria
87
why do the fatty acids need to get into the mitochondria of cells
because that is where beta oxidation occurs
88
how does the process of converting fatty acids into fatty acyl-CoA work
1. Fatty acid adds an AMP from ATP and becomes more reactive
| 2. CoA comes and replaces the AMP
89
Can fatty acids diffuse freely across the mitochondrial membrane
Yes, if they are short (12 carbons or less_)
| No, if they are long (most free fatty acids)
90
if longer fatty acids can't diffuse across the mitochondrial membrane then how do they enter the mitochondria
through the acyl-carnitine/carnitine transporter
91
how does the acyl-carnitine/carnitine transporter work
1. fatty acyl-CoA has the acyl-CoA replaced by carnitine
(carnitine acyltransferase 1 does this)
2. Fatty-carnitine moves through the carnitine transporter into the mitochondria
3. Fatty-carnitine has the carnitine replaced by acyl-CoA (done by carnitine acyltransferase 2)
4. carnitine leaves to do the process again
92
what happens to the fatty acyl-CoA in the mitochondria
it goes through beta-oxidation
93
what are the steps of beta-oxidation
1. trans double bond is formed between alpha and beta carbons (creates FADH)
2. Water adds to the double bond and creates an alcohol off of the Beta carbon
3. NAD+ steals the H and electrons from the alcohol creating a carbonyl at the beta carbon (makes NADH)
4. Thiolase uses CoA-SH and replaces the two carbon end with CoA
5. this results in the loss of 2 carbons (Acetyl-CoA) and a new CoA end to the fatty acid
94
What is the Structure of FADH like
a three six-carbon ring molecule
95
for each step of beta oxidation how many NADH, FADH, and Acetyl=CoA do you get
1- FADH
1- NADH
1- Acetyl-CoA (except you get 2 acetyl-CoA on the last round)
96
What happens to the NADH and FADH produced in beta oxidation
they go to the ETS to create ATP
97
What happens to the Acteyl-CoA produced in beta oxidation
it goes through the Citrate cycle to make ATP, NADH, and FADH
98
What kind of double bond is formed in beta oxidation when FAD+ comes in and becomes NADH creating a double bond
trans
99
can the cell easily handle cis double bonds
nope
100
how does the cell handle and breakdown monounsaturated fatty acids
it uses an isomerase to convert cis double bonds to trans double bonds
101
how does the cell handle and breakdown polyunsaturated fatty acids
it uses isomerase to convert the cis double bond at carbon 2 to a trans double bond, and it uses a reductase to reduce all the other cis double bonds
102
what is the step by step process of breaking down a polyunsaturated fatty acid
1. beta oxidation takes off carbons in two carbon segments until the cis double bond is found at the Beta (3rd) carbon
2. Isomerase moves the bond to convert the cis double bond into a trans double bond (just like after the first step of regular beta oxidation)
3. last three steps of beta oxidation occur, and the first step of the next beta oxidation (FADH made)
4. there is now a trans double bond at beta carbon, and the next cis double bond is one carbon away
5. reductase takes these two double bondos, and reduces them into a single double bond in between where the old double bonds were.
6. isomerase acts again to move the double bond back to where it needs to be to do the last three steps of beta oxidation.
103
How do you get rid of the first double bond of a polyunsaturated fat
isomerase comes in and turns it into a trans double bond, then does the last three steps of beta oxidation and cleaves off the two end carbons
104
What happens after you have gotten rid of the first cis double bond of a polyunsaturated fat, and have removed the end 2 carbons
you will do the first step of beta oxidation and create a trans double bond between the alpha and beta carbons
105
what happens when you have a trans double bond between the alpha and beta carbons, and a cis double bond that begins one carbon away
reductase will come in and reduce the two double bonds into one trans double bond in between where the two double bonds were. then isomerase will come in and move the double bond back between the alpha and beta carbons
106
what happens after you have used reductase to turn the two double bonds (of a polyunsaturated fat) into one double bond, then moved i to between the alpha and beta carbon.
you will finish out the last three steps of beta oxidation and continue on.
107
What happens when you try beta oxidation of a fatty acid with an uneven number of carbons
you will do beta oxidation until you have just the three carbons left
108
what is the molecule called that is made up of the last three carbons of an uneven numbered fatty acid that has gone through beta oxidation
propionyl-CoA
109
What happens to the propionyl-CoA that results from the beta-oxidation of an uneven numbered fatty acid
1. bicarbonate, ATP and Biotin are used to add a carboxy group to the middle carbon of propionyl-CoA
2. (Isomeration) the carboxy group is then moved to the third carbon of propionyl-CoA
3. This molecule is succinyl-CoA, it enters the krebs cycle
110
What is required for the carboxylation of propionyl-CoA
1. bicarbonate
2. ATP
3. biotin
111
What does biotin usually do
add a carbon
112
What is required for isomerization of propionyl-CoA (after carboxylation)
Coenzyme B
113
What causes ketone bodies to be made
depletion of oxaloacetate
114
How does the formation of ketone bodies allow beta oxidation to continue
it releases CoA so it can be used more in beta oxidation
115
What is required for acetyl-CoA to enter krebs cycle
oxaloacetate
116
what happens to acetyl-CoA when oxaloacetate is depleted
it is turned into ketone bodies
117
What enzyme does the first step of ketone body formation from acetyl-CoA
thiolase (last step of beta oxidation)
118
What is the process of formation of ketone bodies from acetyl-CoA
1. twp Acetyl-CoAs are joined by thiolase)
| 2. Then one or two reactions occur producing the two ketone bodies
119
where does the formation of ketone bodies take place
in the liver
120
What are the two ketone bodies formed in the liver
1. Acetoacetate
| 2. beta-hydroxybutarate
121
what happens to the ketone bodies acetoacetate and beta-hydroxybutarate after they are formed in the liver
they are exported to the heart, muscle, kidney, and brain to be used as energy
122
What are the building blocks of fatty acid synthesis, What molecules is added one at a time to a growing fatty acid chain
Acetate (though it is malonyl-CoA is where the acetate comes from)
123
What is the function of ACC (Acetyl-CoA carboxylase) in fatty acid synthesis
It is responsible for synthesizing malanyl-CoA from bicarbonate and acetyl-CoA
124
What are the two parts of the ACC
1. biotin Carboxylase
| 2. transcarboxylase
125
what happens at the biotin carboxylase portion of the ACC
1. Biotin binds
| 2. then the ACC Adds bicarbonate to the biotin molecule create a carbonyl group
126
What happens after the ACC has added a carbonyl group to biotin in the biotin carboxylase portion of ACC
The biotin/carbonyl group flips over to the transcarboxylase site
127
what happens in the transcarboxylase site of the ACC
Acetyl-CoA comes and pulls the carbonyl group off of biotin, creating Malonyl-CoA
128
What does malonyl-CoA do in fatty acid synthesis
it is the molecule that adds 2Cs to the fatty acid with each pass through the process
129
what is the fatty acid synthase (FAS)
the enzyme to which malonyl-CoA will bind to, then a fatty acid will elongate from there
130
What is the first molecule to add to FAS
Acetyl-CoA
131
where will the Acetyl-CoA that first attaches to the FAS end up in the fatty acid
it will be the very end, the tail of the fatty acid
132
What are the steps of fatty acid synthesis
1. Acetyl-CoA binds to the FAS
2. Malonyl-CoA binds to the FAS at a different site
3. The acetate portion of Malonyl-CoA is added to the front of the existing Acetyl-CoA, CO2 is given off (CO2 is the other half of malonyl-CoA)
- Now we have a 4 carbon chain with 2 carbonyl groups
4. The back carbonyl is reduced to an alcohol
5. Then the alcohol is dehydrogenated and creates a C-C double bond
6. NADPH is used to reduce the C-C double bond to a C-C single bond.
7. Another Malonyl-CoA binds and goes through the process again
133
What is the overall goal of each round of fatty acid synthesis
to attach a two-C acetate from malonyl-CoA to a growing chain and reduce it
134
Fatty acid synthesis has four enzyme catalyzed steps, what kinds of reactions are they
1. Condensation (adding acetate to the chain)
2. Reduction (carbonyl to alcohol)
3. Dehydration (alcohol to trans alkene)
4. Reduction (alkene to alkane)
135
What happens in the condensation reaction of fatty acid synthesis
the acetate portion of a malonyl-CoA is added to the front of the growing fatty acid. now we have two carbonyl groups (this one is in front) CO2 is released (the Chain becomes 2 C longer)
136
what happens in the first reduction reaction of fatty acid synthesis
the back carbonyl group is reduced to an alcohol by NADPH
137
What happens in the dehydration reaction of fatty acid synthesis
the OH alcohol leaves as water, and a C=C trans double bond is formed
138
What happens in the second reduction reaction of fatty acid synthesis
the double bond is reduced to a single bond by NADPH (it is also after this step that the growing chain moves back to the original binding site, opening up the other for another malonyl-CoA)
139
What happens after the second reduction reaction of fatty acid synthesis
the growing chain moves back to the original binding site, opening up the other for another malonyl-CoA, once that binds the process is repeated over and over again
140
to form palmitate, how many ATP, and Acetyl CoA are used to make the necessary Malonyl-CoA
7 ATP and 7 Acetyle-CoA are used to make the 7 Malonyl-CoA we will need to synthesize palmitate
141
What is needed with the 7 Malonyl-CoA (formed from ATP And Acetyl-CoA) to form palmitate
1. Another Acetyl-CoA
2. 14 NADH (two used per cycle in the reduction reactions)
3. 14 H+ (two used per cycle in the reduction reactions)
4. (we also use the 7 Malonyl-CoA)
142
What are all of the things needed to make palmitate
1. 8 Acetyl-Coa
2. 7 ATP
3. 7 Malonyl-CoA (from 7 of the Acetyl-CoA and the ATP)
4. 14 NADH
5. 14 H+
143
What are all of the products formed when making palmitate
1. 7ADP
2. 7 Pi
3. 7 CO2
4. 8 CoA
5. 14 NADP+
6. 7 H2O
144
In eukaryotes how does the amount of ATP used in fatty acid synthesis change
you use 3 ATP per cycle instead of just one
145
Why do eukaryotes use 3 ATP per cycle instead of just 1
because in eukaryotes Fatty acid synthesis occurs in the cytosol, so Acetyl-CoA is transported out of the mitochondria into the cytosol at the cost of 2 ATP
146
What is required for fatty acid synthesis
NADPH
147
will fatty acid synthesis occur when NADPH levels are low
nope
148
What are the two ways that we get NADPH
1. pentose phosphate pathway
| 2. Malic enzyme
149
Where do we have the pentose phosphate pathway happening
adipocytes, hepatocytes, mammary gland
150
Where do we have the malic enzyme making NADPH
in adipocytes
151
What is the process of making NADPH with the malic enzyme
Malate is oxidized by the malic enzyme and NADP to make Pyruvate, CO2 and NADPH
152
what are the substrates in the malic enzyme creation of NADPH
1. Malate
| 2. NADP+
153
What are the products of the malic enzyme creation of NADPH
1. NADPH
2. Pyruvate
3. COs
4. H+
154
How many NADPH are made by each pass through the malic enzyme
1
155
How many NADPH are made by each pass through the pentose phosphate pathway
2
156
What are the substrates in the pentose phosphate pathwya
1. Glucose-6-phosphate
| 2. two NADP+
157
what are the products of the pentose phosphate pathway
1. two NADPH
| 2. Ribose-5-Phosphate
158
What is the process of getting Acetyl-CoA out of the mitochondria and into the cytosol for fatty acid synthesis
1. Acetyl-CoA and oxaloacetate are syntesized into citrate
2. citrate leaves through the citrate transporter
3. Acetyl-CoA breaks off for fatty acid synthesis
4. Oxaloacetate left is made into malate
5. malate enters the mitochondria through a malate transporter
6. malate is converted back into oxaloacetate ready to do another shuttle
159
What is the simple version of the moving of Acetyl-CoA from the mitocohdria to the cytosol
1. Acetyl-CoA + oxaloacetate --> citrate
2. citrate leaves to cytosol
3. citrate - Acetyl-Coa --> oxaloacetate
4. Oxaloacetate --> malate
5. Malate enters mitochondria
6. Malate --> oxaloacetate
160
What enzyme regulates fatty acid synthesis
ACC
161
what inhibits the ACC
palmitoyl-CoA
162
What activates the ACC
Citrate
163
What causes high levels of citrate that lead to fatty acid synthesis
high levels of Acetyl-CoA in the mitochondria
164
When is fatty acid synthesis inhibited
when energy is needed
165
what hormones lead to phosphorylation and inactivation of the ACC
glucagon and epinepherine
166
What does fatty acyl-CoA desaturase do
desaturates fatty acids at the Delta 9 location (makes a double bond there)
