Carb Metabolism

Description:	UCI SOM Thompson
Category:	Biochemistry
Created by:	droid on 2009-08-15

Question	Answer
Fructokinase is found where	liver
Fructose metabolism pathway	fructose (fructokinase) fructose-1-P (aldolase b) dihydroxyacetone-P + glyceraldehyde (triose kinase) glyceraldehyde-3-P
Fructokinase deficiency	benign
Aldolase b defficiency	hereditary, liver damage and failure, death, hypoglycemic; Pi is sequestered as fructose-1-P; treat by removing fructose
Fructose synthesis occurs where	liver, seminal vesicles, ovaries
Fructose synthesis pathway	glucose, sorbitol, fructose
Lactose synthesis pathway	glucose1P, UDP-glucose, UDP-galactose, lactose
Galactose degradation pathway	galactose (galactokinase) galactose1P (galactose1P uridylytransferase)glucose1P
Galactokinase deficiency	galactose in blood and urine, cataracts
Uridyl transferase deficiency	galactose in blood and urine, cataracts, dysfunction of liver, kidney, spleen, intestine, and brain, DEATH
UDP glucose is used in what	glycogen, proteoglycans, lactose synthesis
Proteoglycans	core protein attached to many long, linear chains of glycosaminoglycans
Glycoproteins	proteins that contain short chains of oligosaccharides that are usually branched
Hurler’s syndrome	mucopolysaccharide disease with corneal clouding
Hunter’s syndrome	mucopolysaccharide disease with no corneal clouding, x-linked
Location of fatty acid synthesis	liver, fat cells
Location of gluconeogensis	liver, kidney
Location of heme synthesis	bone marrow
Location of PPP	liver, fat cells, adrenal cortex, mammary gland
Location of amino acid synthesis and breakdown	liver
Location of urea synthesis	liver
Location of cholesterol synthesis	liver
Location of steroid hormone synthesis	adrenal cortex, gonads
Enantiomers	mirror images
Do we have D or L sugars	D sugars
Epimer	sugars that differ only in one hydroxyl group position
Amylose/amylopectin	starch
Carbohydrate digestive enzymes in intestine	isomaltase, glucoamylase, lactase, sucrase
How do most cells get glucose past the membrane	facilitated diffusion
Glut1 and Glut3	basal transporters for the brain; high affinity, low Km
Glut 2	glucose transporter in intestine, liver, and kidney
Glut 4	glucose transporter in adipose and muscle tissue; regulated by insulin
Glut 5	transports fructose
SGLT1	glucose (or galactose) and sodium transporter into enterocyte cells
Lactose intolerance is cause by	inability to make lactase
Difference between glucokinase and hexokinase	glucokinase is only in the liver, has a high Km and a high Vm, and is not inhibited by glucose6P
Why phosphorylate glucose	1)net negative charge traps molecule in cell 2)conserves energy 3)commits the cell to use the glucose
Glucose to pyruvate structure names, no enzymes	glucose, glucose6P, fructose6P, fructose16bP, glyceraldehyde3P, dihydroxyacetoneP, 13bisphosphoglycerate, 3Pglycerate, 2Pglycerate, phosphenolpyruvate, pyruvate
Glucose to pyruvate enzymes	hexokinase (glucokinase), phosphoglucose isomerase, phosphofructokinase 1, aldolase, triose phosphate isomerase, glyceraldehyde3PDH, phosphoglycerate kinase, phosphoglycero mutase, enolase, pyruvate kinase
Regulated steps in glycolysis (enzyme names)	hexokinase, PFK1, pyruvate kinase
what is 2,3BPG used for	lowers Hb’s affinity for O2
hexokinase regulation	-G6P, +insulin
PFK1 regulation	+F26BP, +AMP, -ATP, -citrate
Pyruvate kinase regulation	-alanine, +F16BP, (in liver, -phosphorylation from cAMP)
Pyruvate to lactate biproduct	NADH goes to NAD+
What kind of Fatty acids feed into glycolysis	only odd number FA through succinyl CoA
Is inactive pyruvate kinase phosphorylated or not	inactive pyruvate kinase is phosphorylated
Pyruvate DH: number of subunits and enzymes; cofactors and regulation	2 subunits, 3 enzymes, 5 cofactors (NAD, FAD, CoA, lipoic acid, TPP), -acetyl CoA, -NADH
Congenital lactic acidosis	pyruvate DH not working; bypass with ketogenic diet
TCA cycle (enzymes included)	acetyl CoA with Oxaloacetate (citrate synthase) citrate (aconitase) isocitrate (isocitrate DH) alpha ketoglutarate (alpha ketoglutarate DH) succinyl CoA (succinate thiokinase) succinate (succinate DH) fumarate (fumurase) malate (malate DH) oxaloacetate
NADH in TCA comes from what rxns	isocitrate DH, alpha ketoglutarate DH, malate DH
FADH in TCA comes from what rxn	succinate DH
GTP in TCA comes from what rxn	succinate thiokinase
CO2 in TCA leaves from what rxn	isocitrate DH, alpha ketoglutarate DH
Alpha ketoglutarate cofactors	FAD, NAD, TPP, lipoic acid, CoA
Regulated TCA steps	citrate synthase, isocitrate DH, alpha ketoglutarate DH
TCA regulators	-ATP, -NADH, -Succinyl CoA, +ADP
Anapleurotic rxns	(fill up) replenish depleted cycle intermediates
Amphibolic cycle	eg TCA cycle; both degredation and biosynthesis processes occur
Other citrate uses	make fatty acids and cholesterol
Other alpha ketoglutarate uses	glutamate and glutamine
Other succinyl CoA uses	needs odd chain fatty acids, isoleucine, methionine, valine; used to make porphyrins
Other fumarate uses	needs aspartate, phenylalanine, tyrosine
Other malate uses	glucose formation
Other oxaloacetate uses	needs/makes amino acids; made from pyruvate and CO2
Glycerol-phosphate shuttle	dihydroxyacetone phosphate oxidizes NADH (cytoplasmic glycerol3PDH) glycerol3P reduces FAD (mitochondrial Glycerol3PDH) only 2 ATP’s
Malate-aspartate shuttle	3ATP’s
Superoxide dismutase	conversts superoxide to hydrogen peroxide
Mutations in superoxide dismuatese leads to	LAS (lu Gherig’s disease)
Glutathione	used in turning hydrogen peroxide into water
Enzymes in converting hydrogen peroxide into water	glutathione peroxidase and glutathione reductase
NADPH	used to reduce glutathione
Goals of PPP	NADPH and nucleotide biosynthesis
Pathways that require NADPH	reduce glutathione, FA synthesis, FA chain elongation, cholesterol synthesis, neurotransmitter synthesis, nucleotide synthesis
PPP oxidative steps	glucose6P to ribulose5P givine off 2 NADPH and CO2
PPP first step enzyme	glucose 6PDH
Transketolase	rxns 5 and 7 in PPP; requires TPP; transfers 2 Carbons
Transaldolase	rxn 6 in PPP; transfers 3 carbons
Glucose6PDH deficiency	acute hemolytic anemia
Tissue dependent on glucose	Brain, RBC, kidney medulla, cornea of eye
% of guconeogenesis in liver and kidney	90% liver 10% kidney
3 purposes of gluconeogenesis	1)production of blood sugar 2)maintain levels of TCA cycle intermediates 3) clears lactate
gluconeogenesis cycle	lactate (lactate DH) or alanine (transamination) to pyruvate (pyruvate carboxylase) oxaloacetate (PEP carboxykinase)… glyceraldehyde3P… (fructose 16Bisphosphotase)… (glucose6phosphotase)
formation of dihydroxyacetoneP in gluconeogenesis	glycerol (kinase) glycerol3P (glycerol 3PDH) dihydroxyacetoneP
is Acetyl CoA a precursor for gluconeogenesis	NO NO NO NO NO
required for pyruvate carboxylase	biotin, CO2, ATP
where is glucose6Pase found	liver and kidney
how many ATP equivalents are needed to make one glucose molecule through gluconeogensis	6
regulation of pyruvate carboxylase	+acetyl CoA
regulation of PEP carboxykinase	+glucagon, +epinephrine, +glucocorticoids, -insulin
regulation of fructose1,6BPase	-F26BP, +ATP, +citrate, +glucagon
regulation of glucose6Pase	+glucagon
cori cycle	reconversion of lactate to glucose in liver
problem with too much ethanol on an empty stomach	makes lots of NADH which then moves NADH rxns towards lactate, glycerolBP, and malate. Also, lactate, alanine, and glycerol are not used for gluconeogenesis
effect of insulin in liver	-cAMP, -PKA, noP on PFK2/F26BPase, +PFK2/-F26BPase, +glycolysis
effect of glucagon/epinephrin in liver	+cAMP, +PKA, P on PFK2/F26BPase, -PFK2/+F26BPase, +gluconeogenesis
effect of epinephrine in muscle	+PKA, P on PFK2/F26BPase, +PFK2/-F26BPase, +glycolysis
effect of insulin in muscle	-PKA, no P on PFK2/F26BPase, -PFK2/+F26BPase, -glycolysis, glucose goes to glycogen
where in the cell is glycogen stored	cytoplasmic granules
3 reasons for glycogen	1)rapid mobilization 2)source of ATP even in absence of O2 3)maintain blood glucose levels
glycogenen	protein that starts it all off; adds up to 8 glucose molecules onto itself after which glycogen synthase takes over
glycogen degredation	glycogen phosphorylase uses an inorganic phosphate (not ATP) to make Glucose1P; debranching enzyme moves last 3 of 4
phosphoglucomutase	glucose1P to glucose6P
glycogen synthesis	glucose1P with UTP (UDP glucose pyrophosphorylase) UDP glucose with 2Pi; UDP glu can’t add until there are 8 glu molecules; UDP glucose (glycogen synthase) branching enzyme (must be 4 glc between each branch)
regulation of glycogen synthase	+G6P, -cAMP dep P
regulation of glycogen phosphorylase	-G6P, -ATP, +P of phosphorylase kinase, (-glucose (liver), + AMP (muscle))
regulation of phosphorylase kinase	+Ca2+, +cAMP dep P
glycogen regulation by epinephrine in liver or muscle	+cAMP, +PKA, P of phosphorylase kinase (active), P of phosphorylase (active), degredation of glycogen
glycogen storage diseases	most are recessive
glucose 6 phosphatase defficiency	increased amount of glycogen with normal structure; liver enlarged, failure to thrive, severe hypoglycemia, ketosis, hyperuricemia, hyperlipemia (give frequent high carb feedings)