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BIochem- Final
Corso Lectures- PPP->glycosides
89
Biochemistry
Professional
12/10/2011

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Term
A patient with Aldolase B deficiency would have problems tolerating what sugar?
Definition
Fructose
Term
What enzyme, unique to the liver, is crucial to fructose metabolism in the liver and what does it turn fructose into?
Definition
FRUCTOKINASE; Fructose-1-Phosphate
Term
What is the action of Aldolase B?
Definition
Breaks F-1-P into Glyceraldehyde and Dihydroxyacetone
Term
What is the fate of Glyceraldehyde from Aldolase B?
Definition
It can be phosphorylated (via Triose Kinase) into Glyceraldehyde-3-P, a glycolysis intermediate
Term
What is the fate of Dihydroxyacetone?
Definition
It is already a glycolysis intermediate
Term
If a patient cannot metabolize fructose, what enzyme is deficient and what are the consequences?
Definition
Aldolase B- liver glycolysis and gluconeogenesis are deficient
HYPOGLYCEMIA
Term
What happens to fructose in most non-liver cells?
Definition
It gets phosphorylated directly to Fructose-6-Phosphate
Term
What does high glucose do to hexokinase action in shunting fructose to glycolysis?
Definition
It slows it down
Term
What happens when Fructose-1-P builds up?
Definition
This is Aldolase B deficiency;
Glycogen breakdown is inhibited
Term
Why do lactate levels increase in Aldolase B deficiency?
Definition
Gluconeogenesis is inhibited, so no Pyruvate conversion
Term
So, again and again, what do we see in Aldolase B deficiency?
Definition
Hypoglycemia; high lactate; low ATP
Term
A patient with galactosemia would have what principle clinical symptom?
Definition
CATARACTS
Term
What enzyme is deficient in non-classical galactosemia?
Definition
Galactokinase
Term
What enzyme is deficient in classical galactosemia?
Definition
Galactose-1-P uridylyltransferase
Term
What two compounds are the primary products of the pentose phosphate pathway?
Definition
NADPH and ribose
Term
What primary reducing agent is made by the pentose phosphate pathway?
Definition
NADPH
Term
What vitamin is critical to the non-oxidative portion of the pentose phosphate pathway?
Definition
THIAMINE
Term
What vitamin is deficient in alcoholics and causes a breakdown in the pentose phosphate pathway?
Definition
THIAMINE
Term
What is the only source of NADPH for the red blood cells?
Definition
Pentose Phosphate Pathway
Term
How many NADPH are produced in the oxidative phase of the pentose phosphate pathway?
Definition
TWO- for antioxidant action and other reduction reactions
Term
What is the effect of thiamine deficiency in alcoholics on the pentose phosphate pathway?
Definition
Slows it down
Term
What is the major enzyme that converts 5C molecules to 6C molecules after the PPP to reenter glycolysis, and what vitamin is required?
Definition
Transketolase; Thiamine
Term
What are two important consequences of thiamine deficiency?
Definition
Anemia, increased oxidative stress
Term
Nigerian med student develops hemolytic anemia after taking primaquine (anti-malarial). Why?
Definition
GLUCOSE -6-P DEHYDROGENASE DEFICIENCY
Term
If a patient has G-6-P Dehydrogenase deficiency, they don't produce NADPH to act on what enzyme that converts oxidized glutathione?
Definition
Glutathione Reductase
Term
Primaquine, in patients with G-6-P Dehydrogenase deficiency, causes a reduced amount of what important compound?
Definition
NADPH, primary reducing agent
Term
What enzyme gets rid of peroxide?
Definition
Glutathione Peroxidase
Term
What is the primary mechanism of hemolysis in hemolytic anemia?
Definition
Too much H2O2 (peroxide)
Term
What is the name of the complex formed from oxidized glutathione and metHemoglobin?
Definition
Heinz Body
Term
What is the prominent antioxidant mechanism in red blood cells?
Definition
Glutathione
Term
What reaction converts superoxide and peroxide into oxygen, water, and hydroxyl radical?
Definition
Haber-Weiss
Term
What reaction breaks hydrogen peroxide into hydroxyl radical and hydroxyl ion, using Fe?
Definition
Fenton Reaction
Term
What does oxidative stress from free radical damage do to membranes?
Definition
Causes RIGIDITY
Term
What is the main mechanism by which cell membranes are damaged by reactive oxygen species?
Definition
Lipid Peroxidation
Term
Patients with a deficiency in what enzyme should not eat Fava beans?
Definition
G-6-P Dehydrogenase (Favism)
Term
What is the compound in Fava beans that is dangerous to people with G-6-P Dehydrogenase deficiency, and what does it do?
Definition
DIVICINE; increases oxidative stress by producing H2O2
Term
True or False: Fatty acids can be used to synthesize glucose?
Definition
FALSE- WE NEVER USE FA's TO MAKE GLUCOSE
Ketone bodies, yes. Glucose, NEVER.
Term
Once glycogen stores are depleted, what becomes the MAJOR source of fuel?
Definition
Amino Acids
Term
What is the main source of energy for gluconeogenesis in the renal medulla?
Definition
GLUTAMINE
Term
Glucagon activates which protein kinase?
Definition
PKA
Term
What 3 steps of glycolysis are irreversible everywhere but in the liver?
Definition
Glucose to G-6-P
Fructose 6-P to Fructose 1,6 bis P
Phosphoenolpyruvate to Pyruvate
Term
What is the difference between hexokinase and glucokinase?
Definition
Hexokinase- everywhere but liver, non regulated
Glucokinase- liver- MUST BE ACTIVATED BY INSULIN
Term
What enzyme is deficient in Von Gierke's Disease, and what is the consequence?
Definition
Glucose-6-Phosphatase, glucose cannot be released
Term
What enzyme converts fructose 1,6,P to fructose 6-P?
Definition
Fructose Bisphosphatase (turned on by glucagon)
Term
How many ATP are produced by glycolysis?
How many ATP are consumed by gluconeogenesis?
Definition
2;
6
Term
What enzyme that produces Lactate regenerates NAD for glycolysis?
Definition
Lactate Dehydrogenase (anaerobic)
Term
Where does all of glycolysis take place?
Definition
The cytoplasm
Term
How does oxaloacetate leave the mitochondria?
Definition
Shuttled as either Malate or Aspartate
Term
What conversion reaction in the mitochondria is mediated by BIOTIN, and what enzyme catalyzes the reaction?
Definition
Pyruvate to Oxaloacetate; Pyruvate Carboxylase
Term
The conversion of pyruvate back to phosphoenolpyruvate requires what vitamin as a cofactor, and is regulated by what hormones?
Definition
BIOTIN; turned on by glucagon and off by insulin
Term
Starting with lactate, which vitamin is needed in gluconeogenesis that is not needed in glycolysis?
Definition
BIOTIN, for reverse step from pyruvate back to phosphoenolpyruvate
Term
What is the result of the Cori cycle?
Definition
Sythesis of glucose in the liver
Term
What is the primary source of carbons for gluconeogenesis?
Definition
AMINO ACIDS
Term
In what form do amino acids leave the TCA cycle?
Definition
Oxaloacetate
Term
What are the two ketogenic amino acids?
Definition
Leucine and Lysine; pvt tim haLL
Term
What is unique about the ketogenic amino acids?
Definition
They cannot synthesize glucose; they can only make ketone bodies
Term
The last step of gluconeogenesis utilizes glucose-6-phosphatase. Where does this take place?
Definition
In the Endoplasmic Reticulum
Term
In determining whether the action of glucagon or insulin dominates, what is most important?
Definition
The GLUCAGON to INSULIN RATIO
Term
What two processes get energy from proteins?
Definition
Gluconeogenesis and ketone body synthesis
Term
Why does the blood concentration of fatty acids stabilize in the fasting state?
Definition
Limitations of solubility and the protein carrier (albumin)
Term
What is the major energy source 8 hours into a fast?
Definition
Liver Glycogen
Term
What is the major energy source 24 hours into a fast?
Definition
Still glycogen, but the majority is depleted and gluconeogenesis is beginning to dominate
Term
What is the major energy source 3 days into a fast?
Definition
Gluconeogenesis
Term
What molecule is the precursor for proteoglycans, glycoproteins, synthesis of galactose, and other cellular carbohydrates?
Definition
UDP-Glucose
Term
What is UDP-glucaronate?
Definition
A precursor for metabolizing things in the liver that are not very soluble- VERY WATER SOLUBLE- important in liver metabolism (glucaronide)
Term
What molecule is the main way that we get rid of heme in the liver? (hint: think of CONJUGATED...)
Definition
Glucuronate, to make bilirubin diglucuronide (Conjugated Bilirubin= SOLUBLE)
Term
What two molecules are required for the synthesis of lactose in the mammary gland?
Definition
UDP-galactose and free glucose
Term
What bond holds the monosaccharides of lactose together, and what are those monosaccharides?
Definition
B1-4 glycosidic; Galactose and Glucose
Term
What are glycosylate d proteins?
Definition
Tags- like license plates- sugars are attached to proteins in the smooth ER
Term
What is Dolicol Phosphate?
Definition
A 5C Isoprenoid ANCHOR on which oligosaccharides are constructed
Term
What drug inhibits the synthesis of Dolicol Phosphate?
Definition
STATINS
Term
How are sugar groups transfered to proteins?
Definition
Dolicol Phosphate
Term
To what amino acid residue of a glycoprotein does dolicol attach oligosaccharides?
Definition
Asn
Term
What is an oligosaccharide?
Definition
A cluster of 6C sugars
Term
What happens if there is a deficiency in the mannose tag of a lysosomal enzyme?
Definition
Mannose normally phosphorylates to Mannose-P- if this does not happen, it does not bind to its receptor and the enzyme never gets to the lysosome
Term
What happens in I-cell disease?
Definition
The lysosomal enzymes don't get glycoprotein tags and never end up in the lysosome
-The lysozome has no function, and continues to grow empty of enzymes until it gets so big that it LYSES the cell
Term
Sorting of enzymes and proteins in the Golgi Apparatus depends on what?
Definition
TAGS made of oligosaccharides
Term
What is the difference between type O blood and types A and B?
Definition
Type O blood has no Galactose OR GalNAc
Antigenic tag- ONLY H SUBSTANCE
Term
What is the difference between Type A and Type B blood?
Definition
Type A blood has GalNAc tag
Type B blood has Galactose tag
Term
What enzyme is defective in Tay Sachs disease, and what does this cause?
Definition
Hexosaminidase A, which removes GalNAc
-defect of digestive enzymes in lysosome
Term
What enzyme is defective in Fabry's disease?
Definition
Alpha Galactosidase
Term
What enzyme is defective in Gaucher's disease?
Definition
Beta Glucosidase
Term
What enzyme is defective in Neimann-Pick Disease?
Definition
Sphingomyelinase
Term
What is a glycan?
Definition
A repeating Dissacharide
Term
What is the action of penicillin?
Definition
Prevents the synthesis of peptide cross links in peptidoglycan
Term
Name 3 repeating disaccharides:
Definition
Hyaluronate; chondroitin; keratan sulfate
Term
What is a proteoglycan?
Definition
A protein with a repeating dissacharide
Term
What is a proteoglycan aggregate?
Definition
Like hyaluronate- a glycan with proteoglycans- a large, bushy, water-absorbent complex that has lots of sugars and cushions joints
Term
How many psychiatrists does it take to change a lightbulb?
Definition
Only one, but the lightbulb has to want to change :)
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