what is the fate of lipid digestion products absorbed by intestinal mucosal cells?
export of short chain fatty acids to the portal blood
re-esteriification of long chain fatty acids forming triacylglycerols
formation of lipoprotein particles: chylomicron
all the above
after an overnight fast which of the following enzymes (proteins) show low activity?
glucokinase in liver
hexokinase in brain
GluT1 transporter
glucose 6 phosphatase in liver
α-ketoglutaric dehydrogenase in brain
which one of the following statements about prostaglandin synthesis is INCORRECT
Phospholipase A2 or phospholipase C release prostaglandin precursors from plasma membrane phospholipids
arachidonic acid is a major precursor of prostaglandins
Prostaglandins are derived from an essential fatty acid
prostaglandins are produced through the action of lipoxygenase
prostaglandins synthesis is inhibited by glucocorticoids and aspirin
uncoupling of oxidative phosphorylation could occur with
A high concentration of glucocorticoids
A high concentration of thyroxine
A high concentration of adrenaline
A high concentration of insulin
A high concentration of glucagon
sodium-glucose transporter in the intestine
act as symport
is located at the serosal side of the intestinal cell membrane
binds ATP
transport both sodium and glucose concentration gradient
GLUT 2 in liver cells and pancreatic β cells
has low Km (high affinity to glucose)
is suitable for glucose uptake during fasting
acts as glucose sensor , along with glucokinase , in β-cells of pancreas
according to Pasteur effect
glycolysis proceeds in a faster rate in presence of oxygen
oxygen decreases the rate of glycolysis
glycolysis produces more ATP from a glucose molecule in absence of oxygen
oxygen decreases the production of ATP from one glucose molecule
the bi-functional enzyme PFK2/fructose2,6-bisphosphatase
controls the level of fructose 2,6-bisphosphate ,hence the activity of PFK1
is phosphorylated by cAMP-dependant protein kinase under the effect of glucagon and epinephrine
is dephosphorylated by protein phosphatase under the effect of insulin
which of the following is true about fatty acid oxidation
the active form of fatty acid is fatty acyl coA
fatty acid is activated by acyl coA synthetase of the inner mitochondrial membrane
with fatty acid activation ATP is hydrolyzed to ADP + inorganic phosphate
Fatty acyl coA is used only for energy production
deficiency of carnitine acyl transferase may NOT lead to
failure of fatty acid oxidation
hypoglycemia
ketoacidosis
hepatomegaly , seizures and cardiomyopathy leading to infantile death
mitochondrial β-oxidation pathway produces propionyl CoA from
fatty acid with odd number of carbons
phytanic acid derived from chlorophyll
both (A) & (b)
neither (A) nor (B)
Zellweger's (cerebro-hepato-renal) syndrome is characterizd by accumulation
phytanic acid
very long chain polyenoic acid
both (A) & (B)
ِAn enzyme is not involved in glycolysis in muscle is
aldolase
glyceraldehyde 3-phosphate dehydrogenase
enolase
pyruvate kinase
bisphosphoglycerate mutase
the best description of the difference between glucokinase and hexokinase is
hexokinase is found in liver and kidney , while hexokinase is present in nearly all tissues
hexokinase has much higher Km for glucose
glucokinase is found only in tissues that are totally dependent on glucose for fuel , such as brain & RBCs
glucokinase & hexokinase are zymogens
glucokinase but not hexokinase is induced by insulin
An abnormal accumulation of galactose 1-p in liver is usually caused by a deficiency
glucose 6-phosphate dehydrogenase
glucose 6-phosphatse
galactokinase
galactose 1-phosphate uridylyl transferase
hexokinase
the oxidative decarboxylation of all α-keto acids is similar to that of pyruvate. A common requirment for all is
NADP
Acetyl CoA
Lipoic acid
α -ketoglutarate
GDP
mitochondria in brown fat of human infants increase heat generation .this result from an increased rate of electron transport due to
inhibition of ADP-ATP antiporter
inhibition of F1-Fo ATP synthase
blockage of NADH reoxidation
increased permeability of the inner mitochondrial membrane
decreased rate of oxygen consumption
all the electron carrying groups of the respiratory chain
are fixed to the inner mitochondrial membrane
are arranged in an order of descending redox potential
contain iron as an electron acceptor
participate in the building up of the proton gradient
none of the above
the following enzyme is a constituent of pentose phosphate pathway
glucose 6-phosphatase
phosphorylase
phosphohexoisomerase
a substance that is not an intermediate in formation of glucuronic acid from glucose
UDP-galactose
UDP-glucose
Glucose 6-phosphate
UDP-glucuronic acid
glucose 1-phosphate
in the break down of muscle glycogen the predominant product is
glucose
maltose
maltriose
the regulation of glycogenolysis in muscle differ from that in the liver
muscles lack receptors of glucagon
only the liver uses β-adrenergic receptors for this regulation
only muscles respond to epinephrine
muscle glycogenolysis does not respond to stimulation by intracellular calcium
muscle produces mostly glucose from glycogen
mammalian fatty acids desaturase systems introduce double bonds
at Δ4, Δ5, Δ6, Δ9 positions
at ω3, ω6 and ω9 positions
between an existing double bond and methyl carbon
lypolysis in adipose tissue is initiated by
Food intake
fasting
high insulin/glucagon ratio
high fatty acid concentration
The enzyme required for both the synthesis of acetoacetate and its utilization as a fuel is
succinyl coA : acetoacetate CoA transferase
HMG-CoA synthase
thiolase
HMG-CoA lyase
β-hydroxybutyrate dehydrogenase
Receptor-mediated uptake of excess LDL results in all the following Except
increased estrification of cholesterol
increased production of mevalonate
decreased synthesis of HMG-CoA reductase
decreased synthesis of the LDL recepttor
decreased receptor-mediated endocytosis of LDL
In man serum lipoprotein fraction with the highest cholesterol content is
α-lipoprotein
β-lipoprotein
pre β-lipoprotein
chylomicrons
pre-albumin
secondary bile acids are distinguishable from the primary bile acids because they lack
glycine
taurine
a hydroxyl group
a methyl group
a carboxylate group
what is the enzyme used for cholesterol storage
HMG-CoA reductase
Lecithin cholesterol acyl transferase
lipoprotein lipase
Acyl CoA cholesterol acyl transferase
cholesterol esterase
cori cycle transfers
alanine from muscle to liver
lactic from liver to muscle
lactic from exercising muscle or RBCs to liver
Glucose from muscle to liver
