Term
| Lipid synthesis is closely tied to |
|
Definition
| gluconeogenesis and FA metabolism |
|
|
Term
| First step in membrane phospholipid or triacylglycerol synthesis is... |
|
Definition
|
|
Term
| Where does phosphatide synthesis occur in mammals? |
|
Definition
Outer mitochondrial membrane
In ER |
|
|
Term
| Glycerol 3-phosphate is primarily from... |
|
Definition
| DHAP in gluconeogenesis (to a lesser extent from glycerol phosphorylation) |
|
|
Term
| Glycerol phosphate acyltransferase acyl chains... |
|
Definition
Acyl chain from acyl CoA added to C-1 (typically saturated)
Acyl chain from acyl CoA added to C-2 (typically unsaturated) |
|
|
Term
| What enzyme can synthesize phosphatide from diacylglycerol? |
|
Definition
|
|
Term
| Phosphatidate is present at the beginning of both... |
|
Definition
| triacylglycerol and phospholipid pathways |
|
|
Term
| Which two enzymes associate to form triacylglycerol synthetase complex and where is it bound? |
|
Definition
Phosphatidic acid phosphatase
Diglyceride acyltransferase
ER membrane |
|
|
Term
| What does phosphatidic acid phosphatase do? |
|
Definition
| Yields diacylglycerol (DAG) from hydrolysis of phosphatidate |
|
|
Term
| What does diglyceride acyltransferase do? |
|
Definition
|
|
Term
| Where is triacylglycerol synthesized and transported to? |
|
Definition
Synthesized in liver
Transported to muscle and adipose tissue |
|
|
Term
| Where does synthesis of membrane lipids occur? |
|
Definition
|
|
Term
| What does membrane lipid synthesis require? |
|
Definition
| Diacylglycerol and an alcohol, one of them must be activated |
|
|
Term
| CDP diacylglycerol reacts with... |
|
Definition
|
|
Term
| CDP-diacylglycerol + inositol -> |
|
Definition
| phosphatidylinositol + CMP |
|
|
Term
| Kinase phosphorylations with phosphatidylinositol yield... |
|
Definition
| phosphatidylinositol 4,5-bisphosphate |
|
|
Term
| Cardiolipin is also called |
|
Definition
|
|
Term
| Phosphatidylglycerol + CMP -> |
|
Definition
|
|
Term
| Cardiolipin located solely in.. |
|
Definition
| inner mitochondrial membrane |
|
|
Term
| What does cardiolipin do? |
|
Definition
| organizes components of oxidative phosphorylation (stearic acid at C-1 and arachidonic acid at C-2) |
|
|
Term
| What is the major component of the cell membrane inner leaflet? |
|
Definition
|
|
Term
| Phosphorylethanolamine is activated by ___ and driven by ____ |
|
Definition
CTP
Pyrophosphate hydrolysis |
|
|
Term
| What is the most common phospholipid in mammals? |
|
Definition
|
|
Term
| If dietary choline is insufficient, where is phosphatidylethanolamine converted into phosphatidylcholine? |
|
Definition
|
|
Term
| What is the source of methyl groups in the conversion of phosphatidylethanolamine to phosphatidylcholine? |
|
Definition
|
|
Term
| Phosphatidylserine makes up ___% of mammalian phospholipids. |
|
Definition
|
|
Term
| How is phosphatidylserine formed? |
|
Definition
| formed from base exchange reaction with phosphatidylcholine or phosphatidylethanolamine |
|
|
Term
| Where is phosphatidylserine typically located? |
|
Definition
| inner leaflet of the lipid bilayer |
|
|
Term
| What happens when phosphatidylserine is moved from the inner leaflet to the outer leaflet? |
|
Definition
| Triggers apoptosis and degradation by phagocytes |
|
|
Term
| What is the general pattern in phosphatidylserine? |
|
Definition
-Activated intermediate formed from phosphorylated substrate and a nucleoside triphosphate
-Activated intermediate then reacts with a hydroxyl group |
|
|
Term
| Sphingolipids are synthesized from... |
|
Definition
|
|
Term
| Where is the highest concentration of ceramide located? |
|
Definition
|
|
Term
| What catalyzes the condensation reaction between palmitoyl CoA and serine to yield 3-ketosphinganine? |
|
Definition
| Serine-palmitoyl transferase |
|
|
Term
| What reduces 3-ketsphinganine to dihydrosphingosine? |
|
Definition
|
|
Term
| The lipid group of dihydrosphingosine is transferred to the amino group of.. |
|
Definition
|
|
Term
| Sphingolipids have ____ ceramide |
|
Definition
|
|
Term
| The acyl group in sphingomyelin is... |
|
Definition
|
|
Term
| The acyl group in cerebroside is... |
|
Definition
| glucose or galactose (from activated UDP donor) |
|
|
Term
|
Definition
| carbohydrate-rich sphingolipids containing acid sugars |
|
|
Term
|
Definition
| complex sphingolipids with branched oligosaccharides (at least one acidic) |
|
|
Term
| Gangliosides are synthesized from... |
|
Definition
UDP-activated glucose
Galactose
N-acetylneuraminate
CMP N-acetylneuraminate |
|
|
Term
| What are gangliosides involved in? |
|
Definition
inflammatory response to bind immune-system cells
Pathological mechanism of cholera toxin |
|
|
Term
|
Definition
| second messengers (cell growth, differentiation, death) and important components of lipid rafts |
|
|
Term
| What causes respiratory distress syndrome? |
|
Definition
| failure of dipalmitoyl phosphatidylcholine biosynthesis |
|
|
Term
| Where is dipalmitoyl phosphatidylcholine found? |
|
Definition
| alveoli extracellular fluid to decrease surface tension and prevent lung collapse |
|
|
Term
| ____ is one of the most common problems for premature infants who do not make enough dipalmitoyl phosphatidylcholine. |
|
Definition
| Respiratory distress syndrome |
|
|
Term
|
Definition
| inability to degrade gangliosides |
|
|
Term
| How are gangliosides degraded? |
|
Definition
| by lysosomes with sequential sugar removal |
|
|
Term
|
Definition
-Swollen neurons
-Weakness and retarded psychomotor skills
-Blindness and dementia by age 2
-Death by age 3 |
|
|
Term
| Missing or deficient ____ results in high concentration of ganglioside GM2 |
|
Definition
|
|
Term
| ____ is a key regulatory enzyme in lipid metabolism |
|
Definition
| Phosphatidic Acid Phosphatase (PAP) |
|
|
Term
| ___ along with ___ regulates extent and type of lipids synthesized |
|
Definition
|
|
Term
| Lower PAP activation leads to... |
|
Definition
| phosphatidylinositol and cardiolipin |
|
|
Term
| Phosphatide regulates ____ and is a cofactor to ____ |
|
Definition
growth of ER and nuclear membrane
stimulate phospholipid synthesis genes |
|
|
Term
| Loss of PAP prevents ____ and causes ____, overactivity leads to _____ |
|
Definition
proper adipose-tissue development
insulin resistance
obesity |
|
|
Term
|
Definition
-modulates membrane fluidity
-is the precursor for steroid hormones and bile salts |
|
|
Term
| All 27 carbon atoms in cholesterol are derived from... |
|
Definition
|
|
Term
| ______ is the key building block in cholesterol biosynthesis and is located in... |
|
Definition
Activated isoprene isopentenyl pyrophosphate
cytoplasm |
|
|
Term
| ____ molecules combine to form squalene located in... |
|
Definition
Six isopentenyl pyrophosphate
ER |
|
|
Term
| Squalene cyclizes to form ____ that is modified to yield cholesterol located in... |
|
Definition
|
|
Term
| ___ and ___ combine to form 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) |
|
Definition
| Acetyl CoA and acetoacetyl CoA |
|
|
Term
| What is the fate of HMG-CoA in the mitochondria? |
|
Definition
| Converted to ketone bodies and distributed to other tissues |
|
|
Term
| What is the fate of HMG-CoA in the cytoplasm? |
|
Definition
| Reduced to mevalonate by HMG-CoA reductase |
|
|
Term
| What is the committed step in cholesterol biosynthesis and what is the equation? |
|
Definition
Formation of mevalonate
HMG-CoA + 2NADPH + 2H+ -> mevalonate + 2NADP+ + CoA |
|
|
Term
| How many molecules of ATP are required to convert mevalonate to 3-isopentenyl pyrophosphate? |
|
Definition
|
|
Term
| The formation of squalene from 6 isopentenyl pyrophosphate molecules begins with... |
|
Definition
| isomerization to dimethylallyl pyrophosphate |
|
|
Term
| ____ catalyzes the condensation of 2 C5 units to produce geranyl pyrophosphate (C10) and PPi |
|
Definition
|
|
Term
| Squalene formed from ____ C15 farnesyl pyrophosphate molecules |
|
Definition
|
|
Term
| The _____ tail-to-tail _____ in the formation of squalene is catalyzed by ____ in the __ and has an _____ cofactor |
|
Definition
reductive
condensation
squalene synthase
ER
NADPH |
|
|
Term
| ____ of squalene yields lanosterol |
|
Definition
| Intramolecular cyclization |
|
|
Term
| The conversion of squalene to lanosterol is activated by... |
|
Definition
| conversion of squalene epoxide by squalene epoxidase |
|
|
Term
| ____ catalyzes the concerted cyclization by protonating the epoxide oxygen, forming the hypothesized carbocation intermediate in lanosterol synthesis |
|
Definition
|
|
Term
| Series of methyl and hydride migration quenches carbocation with the loss of a proton from ___, finally forming lanosterol |
|
Definition
|
|
Term
| How many methyl groups are lost when lanosterol is converted into cholesterol? |
|
Definition
| 3 (one as formate, two as CO2) and an oxidation |
|
|
Term
| Where are the enzymes that catalyze the conversion of lanosterol into cholesterol? |
|
Definition
|
|
Term
| How many steps are there in the conversion of lanosterol to cholesterol? |
|
Definition
|
|
Term
| ____ is the major site of cholesterol biosynthesis (also the intestine) |
|
Definition
|
|
Term
| The rate of cholesterol synthesis is related to... |
|
Definition
|
|
Term
| Cholesterol biosynthesis is regulated by the amount and activity of... |
|
Definition
|
|
Term
| Rate of HMG-CoA reductase mRNA translation inhibited by... |
|
Definition
|
|
Term
| Rate of HMG-CoA reductase mRNA synthesis is controlled by... |
|
Definition
| SREBP (sterol regulating element binding protein) |
|
|
Term
| Progestagens (corpus luteum) |
|
Definition
| progesterone prepares lining of uterus for implantation and maintains pregnancy |
|
|
Term
| Androgen (testes; testosterone) |
|
Definition
| development of male secondary sex characteristics |
|
|
Term
| Estrogens (ovaries; estradiol) |
|
Definition
| development of female secondary sex characteristics |
|
|
Term
| Glucocorticoids (adrenal cortex; cortisol) |
|
Definition
| promote gluconeogenesis and glycogenesis, enhance protein and fat degradation, and inhibit inflammatory response |
|
|
Term
| Minterolcorticoids (adrenal cortex; aldosterone) |
|
Definition
| increase Na+ reabsorption and K+ and H+ secretion, leading to increase in blood volume and blood pressure |
|
|
