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Exam #2
N/A
104
Chemistry
Undergraduate 4
10/17/2014

Additional Chemistry Flashcards

 


 

Cards

Term
How is urea synthesized?
Definition
Proteins are catabolized into amino acids via enzymatic proteolysis. The amino acids undergo transamination and oxidative deamination to be converted into ammonia, which enters the "urea cycle". Urea is synthesized from the "urea cycle"
Term
What are some of the modes of urea excretion?
Definition

90% of urea is excreted through its kidneys

 

There are some losses through the gastrointestinal tract and skin

Term
Disease states and disorders associated with urea (BUN) measurement
Definition

Kidney disease shows accumulation of urea in blood

 

Uremic (azotemic) state: increase in [blood urea] 

Term
Discuss the methodologies used for urea nitrogen (BUN) measurement (pages 369 - 370)
Definition

Fearon Reaction (chemical method): molecules of diacetyl condense with those of urea to form the chromogen diazine, which absorbs strongly at 540 nm.

 

Enzymatic Methods: based on preliminary hydrolysis of urea with urease to generate ammonia; use spectrophotometry (Berthelot reaction and enzymatic assays)

Term
Chemical structure of creatinine
Definition
cyclic anhydride of creatine
Term
Synthesis of Creatinine (see p. 365)
Definition
final product of decomposition of phosphocreatine as well as the spontaneous dehydration of creatine
Term
Mode of creatinine excretion
Definition

Excreted in the urine

 

(note: although it is present in all body fluids and secretions and is freely filtered by the glomerulus)

Term
Clinical significance of creatinine
Definition

marker of glomerular filtration rate

 

implicated in diabetes, hypertension, and congestive heart failure

Term
principle of Jaffe reaction
Definition
creatinine reacts with picrate ion in an alkaline medium to yield an orange-red complex
Term
Analytical problem of Jaffe raction
Definition

lack of specificity for creatinine

 

many compounds have been reported to produce a Jaffe-like chromagen 

Term
The greatest success in common usage and specificity for the Jaffe reaction (chemical method)
Definition
use of a kinetic measurement approach in combination with careful choice of reactant concentrations
Term
Advantages of kinetic assays for Jaffe Reaction
Definition
more specific, faster, and the analysis is automated
Term
Maximum concentration of picrate that can be used in a Jaffe reaction. Also name the concentration range employed in most methods.
Definition

30 mmol/L maximum

 

3 - 16 mmol/L

Term
What can high concentrations of hydroxide cause in the Jaffe reaction?
Definition
interference
Term
Absorbance maximum of the Jaffe reaction
Definition
490 - 500 nm
Term
chemical sructure of uric acid
Definition
nitrogenous compound (2,6,8-trihydroxypurine)
Term
Synthesis of uric acid (p. 370 - 371)
Definition

major product of catabolism of the purine nucleosides adenosine and guanine.

 

Both endogenous and exogenous nucleic acids are degraded/catabolized into uric acid.

Term
Mode of excretion of uric acid
Definition

Highly present in the urine and can be found in serum

 

 

Did you know that it can be crystallized in the serum and deposited in the joints?

Term
Clinical significance of uric acid
Definition

there are more than 20 disorders of purine metabolism that cause hyperuricemia and hypouricemia

 

suspicious symptoms: kidney failure/stones in children or young adult, unexplained neurological problems in infant - adolescent, gout in man/woman <30 years old

Term
Cause of gout
Definition
monosodium urate precipitates from supersaturated body fluids
Term
What are the three methods to measure uric acid?
Definition
Phosphotungstic Acid Method, Uricase Method, and HPLC Method
Term
Drawback of the Phosphotungstic Acid (PTA) Method
Definition
sunject to many interferences
Term
Advantage of the Uricase Methods
Definition
more specific than the PTA methods
Term
Carbohydrate
Definition
aldehyde or ketone derivatives of polyhydroxy alcohols composed of carbon, hydrogen, and oxygen in a ratio of 1:2:1
Term
Monosaccharide
Definition
a simple sugar that consists of a single polyhydroxy aldehyde or ketone unit and is unable to hydrolyzed to a simple form
Term
Disaccharide
Definition
two monosaccharides joined covalently by an O-glycosidic bond, with the loss of a water molecule.
Term
Polysaccharide
Definition
the linkage of multiple monosaccharide units
Term
glycosidic linkage
Definition
chemical bond between monosaccharides?
Term
Aldose
Definition
 monosaccharide (a simple sugar) that contains only one aldehyde (-CH=O) group per molecule
Term
Ketose
Definition
a monosaccharide containing one ketone group per molecule.
Term
Hexose
Definition
any of the class of simple sugars whose molecules contain six carbon atoms, such as glucose and fructose.
Term
Isomer
Definition
each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties
Term
Stereoisomer
Definition
compounds that are identical in composition and differ only in spatial configuration
Term
Glycogenesis
Definition
formation of glycogen from glucose
Term
Glycogenolysis
Definition
the breakdown of glycogen to glucose
Term
Gluconeogenesis
Definition
production of glucose from noncarbohydrate sources
Term
Glycolysis
Definition
the breakdown of glucose by enzymes, releasing energy and pyruvic acid
Term
Anaerobic Glycolysis
Definition
transformation of glucose to pyruvate when limited amounts of oxygen
Term
Acetyl-coenzyme A
Definition
acetyl ester of coenzyme A, involved as an acetylating agent in many biochemical processes
Term
Glycogen
Definition
an extensively branched polysaccharide containing many glucose residues and found particularly in muscle and liver cells for glucose storage
Term
Lipogenesis
Definition
the metabolic formation of fat/lipids
Term
Lipolysis
Definition
the breakdown of fats and other lipids by hydrolysis to release fatty acids
Term
Components of Maltose
Definition
Glucose + Glucose
Term
Components of Lactose
Definition
Glucose + Galactose
Term
Components of Sucrose
Definition
Glucose + Fructose
Term
Starch Composition
Definition
a mixture of amyloses and amylopectins
Term
Glycogen Composition
Definition
similar to amylopectins, but branching is more extensive and is evident every 8 to 12 glucose residues
Term
Clinical Significance of Glycogen
Definition
Glycogen Storage Disease (p. 382)
Term
Glycoprotein composition
Definition
proteins that have carbohydrate groups attached to the polypeptide chain
Term
proteoglycan composition
Definition
protein bonded to glycosaminoglycan groups
Term
Ingestion and Absorption of Carbohydrate
Definition

Once eaten, amylase (salivary) breaks down starch into glucose and disaccharides into monosaccharides

 

Carbohydrates are absorbed in the intestines and liver

Term
main physiological functions of glucose
Definition

structureal components in RNA and DNA

 

source of energy

Term
pentose phosphate pathway
Definition
a biochemical pathway parallel to glycolysis that generates NADPH and pentoses (5-carbon sugars)
Term
Embden-Meyerhof pathway
Definition
metabolic pathway that converts glucose to pyruvate
Term
Insulin effect in regulating blood glucose level
Definition
It decreases blood glucose level via glycogenesis, glucose uptake (entering the cell), and lipogenesis
Term
Effects of glucagon in reguling blood glucose levels
Definition
increases blood glucose via glycogenolysis and gluconeogenesis
Term
Maintenance of blood glucose levels in "fasting state"
Definition

1) Decrease in blood [glucose] stimulate α-cells of pancreas to secrete glucagon

 

2) Glucagon causes lipolysis, glycogenolysis, and gluconeogenesis to occur, yielding normal blood [glucose]

Term
The maintenance of glucose levels in the "fed state"
Definition

1) An increase in blood [glucose] cause the β-cells of the pancreas to release insulin

 

2) Insulin causes lipogenesis, glucose uptake, and glycogenesis to occur

Term
Growth hormone effect on blood glucose levels
Definition
The growth hormone stimulates gluconeogenesis, enhances lipolysis, and antagonizes insulin-stimulated glucose uptake
Term
Type 1 Diabetes Mellitus
Definition

Abrupt onset of symptoms: polyuria, polydipsia, and rapid weight loss

 

Insulinopenia (deficiency of insulin) due to loss of pancreatic β cells; autoantibody may be involved

 

Peak incidence occurs in childhood and adolescence

 

 

Term
Type 2 Diabetes Mellitus
Definition

Minimal symptoms, not prone to ketosis, and not dependent on insulin

 

[Insulin] may be normal, decreased, or increased; insulin action may be impaired

 

Obesity is commonly associated

 

 

 

 

Term
Gestational Diabetes Mellitus
Definition
Carbohydrate intolerance of variable severity with onset or first recognition during pregnancy.
Term
Risks for Gestational Diabetes Mellitus
Definition

1) women who have marked hyperglycemia during or soon after pregnancy

 

2) women who are obese

 

3) women whose GDM was diagnosed before 24 weeks' gestation

Term
Principle of glucose oxidase method
Definition

Glucose + H2O + O2 →(glucose oxidase)→ Glucaronic Acid + H2O2

 

H2O2 + Reducing Dye (color #1) →(peroxidase)→ Oxidized Dye + H2O

 

The more oxidied dye there is, the more H2O2 produced, thus, the more glucose initially present

Term
Interferences of the Glucose Oxidase method
Definition
uric acid, ascorbic acid, and bilirubin
Term
Principle of Hexokinase Method
Definition

Glucose is phosphorylated in presence of hexokinase and forms Glucose-6-phosphate. Glucose-6-phosphate is oxidized by G6PD to another product in the presence of NADP+ or NAD+

 

The amount of reduced NADP or NADH produced is directly proportional to the amount of glucose in sample (340 nm ABS)

Term
Required Sample Types for Hexokinase Method
Definition

plasma or serum.

 

NaF, with an anticoagulant may be used

 

Term
Sources of Interferences for Hexokinase Methods
Definition

Hemolyzed specimens containing more than 0.5g of Hgb/dL 

 

drugs, bilirubin, and lipemia

Term
Specimens for Glucose Oxidase Method
Definition
CSF
Term
Method used in lab to measure Glycohemoglobin A1C
Definition
Helena GLYCO-Tek Affinity Column Method
Term
Principle of the Helena GLYCO-Tek Affinity Column Method
Definition

The dihydroxyboryl group in the cellulose reesin has an affinity to cis-diol groups on simple sugars, thus allowing separation of glycated hemoglobins from non-glycated.

 

Elution with a basic developer removes non-glycated Hb. The glycated forms are eluted using sorbitol buffer. Then spectrophotometry

Term
Specimen for Glycohemoglobin methods
Definition
Fresh, whole blood containing EDTA, heparin, or citrate. Packed cells are the specimen of choice.
Term
Interfering substances for the Glycohemoglobin method
Definition
hemolyzed, lipemic, and icteric specimens
Term
Patient Preparation for Glucose Tolerance Test
Definition

1) Patient has 3 days of unrestricted diet

2) Collect blood after patient has fasted for at least 8 hrs

 

Term
Procedure for Glucose Tolerance Test
Definition

1) Collect patient sample from 8-hour fast

2) Give 75g of glucose

3) Collect blood every half hour (up to 2 hours)

4) Patient is considered diabetic if the 2-hour test tube (and another test tube) is >200 mg/dL

 

Normally, 7% of blood glucose is lost every hour (cellular glycolysis)

Term
GTT normal glucose level
Definition
70 - 90 mg/dL
Term
Criteria for diagnosing Diabetes Mellitus in fasting plasma glucose
Definition
≥126 mg/dL (7.0 mmol/L)
Term
Criteria for diagnosing Diabetes Mellitus in 2-hour plasma glucose
Definition
≥200 mg/dL (11.1 mmol/L)
Term
The two families of protein that modulate glucose transport into the cells
Definition

1) sodium-dependent glucose transporter (promote the uptake of glucose and galactose from the lumen of the small bowel and their reabsorption from urine in the kidney)

 

2) facilitative glucose transporter (located on the surface of all cells)

Term
Methods used to measure ketones in body fluids
Definition

1) Acetest

 

2) Ketostix

 

3) Determination of β-hydroxybutyrate

Term
Most common analytical method of ketones
Definition
sodium nitroferricyanide + ketones yield a purple complex
Term
Qualitative Method to measure Glucose in Urine
Definition

Benedict's Test

 

Aldose + Cu(citrate)22- (blue) → carboxylate anion and Cu2O (brick red ppt)

 

If the color of the solution changes, glucose is present (spectrophotometry?)

Term
Quantitative Methods to measure Glucose in Urine
Definition
Hexokinase and glucose dehydrogenase procedures are recommended for greatest accuracy
Term
Quantitative Method to measure Glucose in CSF
Definition
Glucose oxidase
Term
Three Methods for Determination of Glycated Hemoglobins
Definition

1) High-Performance Liquid Chromatography

2) Immunoassay

3) Affinity Chromatography (*done in lab)

Term
Lipids
Definition
a class of compounds that are soluble in organic solvents but are nearly insoluble in water and that contain nonpolar carbon-hydrogen bonds
Term
Simple lipid
Definition
compound that contains fatty acids and no prosthetic groups; simple fatty acids; monomers of complex lipids
Term
Complex lipid
Definition
Lipid containing esters, fatty acids, alcohol groups, and other prosthetic groups; a macromolecule composed of simple lipids (e.g. triglycerides)
Term
triglyceride
Definition
an organic compound made up of glycerol and three fatty acid chains. Fat is stored as triglycerides
Term
phospholipid
Definition
a polar amphipathic lipid located on the surface of a lipoprotein; they are also found at the aqueous interface of biological membranes
Term
Lecithin
Definition

any group of yellow-brownish fatty substances occurring in animal and plant tissues composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and phospholipids.


major surfactant found in the lung; used along with sphingomyelin to assess fetal lung maturity

Term
Sphingomyelin
Definition

a lipid compound that coats lung cells

 

substance that occurs widely in brain and nervous tissue, consisting of complex phosphoryl derivatives of sphingosine and choline

Term
Glycolipid
Definition
a lipid with a carbohydrate component
Term
apoprotein
Definition

protein that together with a prosthetic group forms a particular biochemical molecule such as a hormone or enzyme


apolipoproteins are the major components of lipoproteins

Term
Lipoprotein
Definition
spherical particles involved in the transport of lipids with nonpolar neutral lipids (triglycerides and cholesterol esters) in their core and more polar amphipathic lipids (phospholipids and free cholesterol) at their surface
Term
lipase
Definition
  1. a pancreatic enzyme that catalyzes the breakdown of fats to fatty acids and glycerol or other alcohols
Term
lipemia
Definition
the presence in the blood of an abnormally high concentration of emulsified fat
Term
Saturated fatty acids vs. unsaturated types
Definition

Saturated fatty acids have no double bond between their carbons

 

Monounsaturated fatty acids contain one double bond

Polyunsaturated fatty acids contain multiple double bonds

Term
Chylomicron
Definition

A microscopically visible particle appearing in the plasma after a fatty meal.

 

Over 90% of TGL make up chylomicrons

Term
VLDL - Very Low Density Lipoprotein
Definition

Composition: 50-65% TGL, 15% cholesterol, +proteins

 

Function: carries endogenous cholesterol and other TGL from liver to tissues

Term
LDL = Low Density Lipoprotein
Definition

Composition: primarily cholesterol about 50%

 

Function: primary chosterol transport from liver to tissues; transports most of the TGLs?

Term
HDL = High Density Lipoprotein
Definition

Composition: AI & AII apolipoprotein and contains cholesterol ester

 

Function: "cholesterol scavenger"; esterification of cholesterol and transports cholesterol from tissues to liver, where it is converted to bile acids and excreted.

Term
Emusification and absorption of dietary lipids
Definition
The digestive enzyme, lipase, is water soluble and can only work at the surface of fat globules.  Digestion is greatly aided by emulsification, the breaking up of fat globules into much smaller emulsion dropletsBile salts and phospholipids areamphipathic molecules that are present in the bile. Motility in the small intestine breaks fat globules apart into small droplets that are coated with bile salts and phospholipids, preventing the emulsion droplets from re-associating
Term
Physiological Function of Lipids
Definition
hormones, energy source, assisting digestion, structural component of cellular membrane
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