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38 Cards in this Set
- Front
- Back
FA metabolism makes Fatty acids for what molecules (list structure)
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Triacylglycerols (3FA + glycerol backbone)(main E)
Phospholipids ( 2FA + phos'd glycerol) Cholesterol ester (1FA + steroid ring) |
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Where does FA come from? / is degraded back down to?
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Acetyl CoA
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For structure see page 62
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lkh
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how long are:
SCFA MCFA LCFA VLCFA |
s - 2-6 C
m - 6-12 l - 14-20 verylong - 22 and up |
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is a cis or trans dbl bond a kink?
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cis
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how far apart must dbl bonds be?
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at least 3 C's apart
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which carbon in linoleic acid is C1, carboxy end or methyl end
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the carboxy carbon
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palmitic acid
palmitoleic acid |
16:0
16: 1 delta9 |
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stearic acid
oleic acid linoleic acid Alpha-linolenic acid |
stearic: 18:0
oleic: 18:1 delta9 Linoleic: 18:2 delta 9,12 alpha-linoleic: 18:3 delta 9,12,15 |
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arachidonic acid
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20:4 delta 5,8,11,14
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which ones are in the omega-6 family?
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linoleic and arachidonic acid
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which are omega-3?
omega-7? |
omega-3: alpha-linolenic
omega-7: palmitoleic |
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where does FA synthesis occur
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cytosol (liver adipose CNS and mammary)
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overall reaction of FA synthesis
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8 acetyl CoA
7 ATP 14 NAPH makes palmitate 16:0 CoAsh, NADP and water |
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FA synthesis
exergonic vs endergonic reductive vs oxidative |
endergonic and reductive
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Acetyl CoA
structure |
acetyl group - long flexible phosphopantetheine group - Ribose - adenine
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panothenic acid, how synthesized in humans
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not, its an essential nutrient
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Acetyl CoA carboxylase
what it does coenzymes? |
AcetylCoA + CO2 + ATP --> malonyl CoA + ADP + Pi
BIOTIN as a co-enz PROSTHETIC GROUP (cov bound) swinging arm binds CO2 like in pyruvate carboxylase of gluconeogenesis |
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Acetyl CoA carboxylase
importance of the step it catalyzes allosteric effectors (+and-) |
makes malonyl CoA in a committed rate limiting irrev step
Allosteric effectors: + citrate - palmitic acid (end product) |
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Acetyl CoA carboxylase
covalent regulation what causes a positive allosteric effect or a negative allosteric effect |
inactive when phosphorylated
deP'd when insulin is high (insulin/glucagon ratio is high) P'd when glucagon is high by AMPK (in assoc with PKA) |
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FAS
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Fatty acid synthase
catalyzes malonyl CoA and Acetyl CoA to palmitate 7 catalytc activities and an ACP carrier protein domain |
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ACP domain
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has a posphopantetheine group like in acetyl CoA, uses this swinging arm to link intermediates
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Describe/ draw out FAS activity
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Tranferase: takes malonyl CoA and Acetyl CoA and makes malonyl-s-ACP and acetyl s-ACP
combine the two using condensing enzyme (CO2 leaves) Reduce - beta-ketoacyl reductase (uses NADPH) Dehydrate (dbl bond between alpha and beta C): beta-Hydroxylacyl dehydratase Reduce - transenoyl reductase (uses NADPH) repeatedly combine with malonyl-s-ACP till you get palmitoyl-s-ACP (16:0) cleave off s-ACP using thioesterase |
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if you use methylmalonyl CoA instead of malonyl CoA what happens
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you make branched chain FA
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explain transport of Acetyl CoA out of mito and into cytosol where FA synthesis occurs
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Mito:
Acetyl CoA + OAA --> citrate via citrate synthase citrate is shuttled out Cytosol: citrate -->Acetyl CoA and OAA via Citrate lyase OAA --> malate via malate DeH malate goes into mito and this drives the malate citrate transporter, once in mito malate is converted back to OAA (which can then combine with acetyl CoA to make citrate) |
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Refresher how does pyruvate get into the mito?
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proton pyruvate symporter, uses inter membrane proton gradient
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where else can you get a source of NADPH (remember you use two per addition of malonyl) besides pentose pathway?
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malate + nadp --> pyruvate + NADPH
via malic enz |
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refresher
oxidative portion of pentose pathway |
G6P -(DeH)-> lactone -(lactonase)-> glucontate -(DeH)->
ribose-5-p + CO2 + 2NADPH |
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How does elongation of DIETARY FA differ from de novo?
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more than one enz
ER bound! CoA (not ACP) Substrates are over 10C long |
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How many NADPH does de NOVO syn take to make palmitoyl?
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14 NADPH
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in dietary elongation how many NADPH per C added?
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1 nadph per C (like in de novoe)
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Where are the C from malonyl CoA added into dietary FA?
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R-CH2CH2-C(=O)SCoA
at carboxy carbon |
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Question on counting the C's in FAsynthase, follow the C's from malonyl and acetyl, where is alpha beta, where does dbl bond insert
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???
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Desaturation of dietary FA
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insertion of dbl bond, uses :
desaturase cytochrome b NADH cytochrom b reductase ER! |
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Where can humans place dbl bonds
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at 9, 6, 5, and 4 (the four types of desaturases)
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where is the limit of desaturation in humans
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cannot insert beyond C10
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What family of FA's can humans not synthesis
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omega-6 and omega-3
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how do you make arachidonic acid from linoleic? (omega-6)
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linoleic 18: delta 9,12
desat at 6 (three C's away) elongate to 2 C's (pushes dbl bonds further away from C1) Desaturate at 5 get 20:4 5,8,11,14 |