Upgrade to remove ads
Only $2.99/month

FDSC 410 Exam 1

Terms in this set (92)

Accuracy (Erel, Eabs)
A measure of the agreement between the experimental value and the actual amount of the substance in the matrix
Precision (SD, %CV, SEM, CI)
Measures the closeness of individual measurements
Specificity/Selectivity
The extent to which a method can determine particular analytes in mixtures or matrices without interferences from other components
Sensitivity
The smallest amount of difference in quantity that will change an instrument's reading (steeper slope means more sensitive)
Sources of Error
These are errors that you make in the lab which result in either increased or decreased yields. Systematic error, random error, and blunders
Limit of Detection
lowest possible increment that can be detected with statistical significance
Calibration
The action or process of calibrating an instrument or experimental readings. To adjust or mark (something, such as a measuring device) so that it can be used in an accurate and exact way
Significant figures
The number of important single digits (0 through 9 inclusive) in the coefficient of an expression in scientific notation .
T test
A statistical test used to evaluate the size and significance of the difference between two means
Sample vs. Population
Sample is a subset of the population. Population is a particular section, group, or type of people or animals living in an area or country.
Sampling
the action or process of taking samples of something for analysis.
Sampling Plan
a plan that specifies a sample size, the time between successive samples, and decision rules that determine when action should be taken
Attribute Sampling
that an item being sampled either will or won't possess certain qualities, or attributes.
Variable Sampling
the process used to predict the value of a specific variable within a population
Sampling Bias
a bias in which a sample is collected in such a way that some members of the intended population have a lower sampling probability than others.
Probability Sampling
a sampling technique in which sample from a larger population are chosen using a method based on the theory of probability. For a participant to be considered as a probability sample, he/she must be selected using a random selection.
Statistical Process Control
a system in which management collects and analyzes information about the production process to pinpoint quality problems in the production system
Random Error
Can fluctuate and are unavoidable (ex: differences between balances)
Systematic Error
results consistently deviate from true value (ex: pipette calibrated incorrectly)
Enzyme
a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.
Catalyst
substance that speeds up the rate of a chemical reaction
Coenzyme/Cofactor
substances such as vitamins and minerals that help enzymes catalyze chemical reactions
Michelis- Menten Kinetics
When [S] << Km used to measure substrate conc
When [S]>> Km used to measure enzyme conc
Effect of [E] on reaction rate V, more enzyme creates more product in a short amount of time (it goes faster)
Lineweaver-Burke plot
Important because it gives you Km and Vmax of a reaction.
X axis is 1/[S] and units are 1/mmol
Y axis is 1/V and units are mmol/time
Y intercept is 1/Vmax
Slope is Km/Vmax
Km
Michaelis-Menten constant: a measurement of the affinity of the enzyme of the substrate. A lower value means the enzyme binds the substrate strongly.
Vmax
Maximum rate of reaction. How fast can the enzyme go when it is saturated with respect to substrate.
Steady state reaction
A steady state is a situation in which all state variables are constant in spite of ongoing processes that strive to change them. For example, a bathtub with the faucet running but also with the drain unplugged.
Polyphenol Oxidase
An enzyme in plants, animals, and some microorganisms that causes enzymatic browning to occur more quickly. Requires Cu2+ and oxygen to be activated.
Amylase
-Salivary and Pancreatic amylase
-splits starch into dextrin and dextrin into glucose
Lipoxygenase
-Catalyzes peroxidation of fatty acids
-abstracts a hydrogen, allows reaction with oxygen, free radicals produced
-leads to rancidity and flavor
-Co-oxidations
The ________ of a solution is defined as the ratio of P/P0, or the radiant power of beam exiting the absorption cell over the radiant power of the beam incident on absorption cell
Transmittance
What is a, b and c in Beer's Law (A=abc)?
a= absorptivity (cm-1*conc-1)
b= pathlength through solution (cm)
c= concentration of analyte (M, mM, mg/ml, %)
________ is measured from a change in dipole moment.
Infrared Spectroscopy
Which molecular vibration does not show (or would be very unlikely to show) a change in a dipole moment?
Symmetric Stretch
Mid IR spectrometry is useful for studying ______ compounds because the absorption bands are related to the vibrational modes of specific functional groups.
Milk
This type of wavelength region has a range of 380-750 micrometers and is used in absorption, emission and fluorescence spectrometry.
Visible region
Antibody
Immunoglobulin. Proteins produced by B cells in response to antigens. Highly specific and high affinity.
Antigen
Any molecule that induces the formation of antibodies and can bind antibodies. Generally large molecules
Hapten
small molecules must be linked to a large carrier protein to generate an immune response
Epitope
specific regions of antigen to which antibody is bound
ELISA
Enzyme-linked immunosorbent assay. A plate-based assay technique designed for detection. Enzymes serve as amplification method so target molecule can be detected. Quantify reaction visually or spectrophotometrically.
Direct detection
reporter molecule is located on the primary antibody.
Indirect detection
reporter molecule is located on the secondary antibody
Primary antibody
binds to protein of interest
Secondary antibody
binds to primary antibody
Non-competitive assay
Only detection antigen binds to antibody molecules. Absorbance directly related concentration of target molecule, the larger the signal/absorbance the more the target analyte you have present.
Competitive assay
Competition between the sample antigen and an added antigen in binding to the antibody. Absorbance inversely related concentration of target molecule, the larger the signal the less of the target analyte you have present.
Sally was working on her second part of the enzyme lab exercise. She begins by peeling a cooked potato and cut it into pieces. She then weighs 100 grams of the potato and mixes it with very hot buffer A. She grinds and blends the mixture for about 1 minute, then filters the mixture through Whatman no. 1 paper and transfers the clear solution into a hot Erlenmeyer flask.
She then transfers buffer B, sulfite solution and water in test tubes 1-12. She set the wavelength on the spectrometer to 4.75 nm and zeros the instrument with apple juice.
-not 100g, 10 g and potato is not cooked its raw and cold
-want ice cold buffer not hot buffer
-transfer into ice cold erlenmeyer flask not hot erlenmeyer flask
-Not water, its DOPA +buffer B in tubes 1-12. Enzyme extract in 2-12 and sulfite solution only in 12
-wavelength is not 4.75 but 475nm
-Zero instrument with distilled water
If method A is reported to be more specific and accurate, but less precise than method B, that means that method A than method B.
-shows less interferences
-the measurement is closer to the true value
-has a larger standard deviation
Method A: mean=19.6 SD=0.055
Method B: mean=20.2 SD=0.134
1. Which method is more precise?
2. Which method is more accurate?
3.The standard deviation (SD) was calculated using (n-1)instead of just n. Would the SD be smaller or larger if just n would have been used?
4.You have determined that you would only accept Method B if the measured values would fall within 2 SD from the mean - what range of values is acceptable?
5.Does the provided data provide any information about the specificity of the two methods?
1. Method A
2. Method B
3. Smaller
4. 19.9-20.5
5. No
What is the difference between absolute error and relative error? Check all the statements that are true.
-relative error = absolute error/true value
-relative error = (mean - true value)/true value
-The relative error is more useful than the absolute error because it measures the relative error, independent of the magnitude of the measurement.
-absolute error = (mean - true value)
How many significant figures are in the following numbers:
1: 0.00034
2: 6.980
3: 17.003
1: 2
2: 4
3: 5
What is the correct number of significant figures for the following calculation? (1.78*0.07913)/4.28469
3
What is the correct results including the correct number of significant figures for the following calculation?(1.78*0.07913)/4.28469
0.0329
Match Km in the MM equation
Michelis constant; affected by enzyme type, substrate, temperature, pH and inhibitors
X axis of Lineweaver-Burk plot
inverse of substrate concentration
Match Vmax in the MM equation
Maximum Velocity; affected by enzyme type, substrate, concentration, temperature, pH, and certain types of inhibitors
Y axis Lineweaver-Burk plot
Inverse of initial velocity
Slope of Lineweaver-Burk plot
ratio of Michelis constant to maximum velocity
Intercept of Lineweaver-Burk plot
Inverse of maximum velocity
Select the various methods that can be used to quantify enzyme activity in enzyme-catalyzed reactions
-isotope measurements
-viscosity measurements
-absorbance spectrometry
-titration
-mass spectrometry
-fluorimetry
-manometric measurements
-chomatography
According to the Food Technology article, check all boxes that apply for the use of proteases in foods
-increase protein functionality
-increase protein solubility
-decrease protein viscosity
Using an enzymatic assay, adulteration of ["Apple juice", "Orange juice", "Lime juice"] can be measured by quantitation of D-Malic acid. The reaction is catalyzed by DMD ["D-malic hydrogenase", "D-malate dehydrogenase", "L-malic dehydrogenase"] , where
D-Malic Acid + ["NADH", "NAD+"] --DMD--> CO2 + pyruvate + ["NAD+", "NADH"] + H+.
The formation of ["NADH", "pyruvate", "CO2", "H+"] is measured photometrically at ["253", "492", "340", "420"] nm.
-apple juice
-D-malate dehydrogenase
-NAD+
-NADH
-NADH
-340
Usual wavelength range of 0.6-10 m
NMR spectroscopy
Stretching and bending motions of molecular bonds
IR spectroscopy
Usual wavelength range 780-300,000 nm
IR spectroscopy
Usual wavelength 180-380 nm
UV spectroscopy
Absorption, emission, and fluorescence spectroscopy between 380-750 nm
Visible spectroscopy
Which of these two wavelengths would you use to quantitatively determine cyanidin-3-O-glucoside?
518 nm because it is larger/taller and therefore more sensitive
Carboxyl groups (-COOH) absorb strongly in the IR region between 1700 to 1750 cm-1.
Looking at these three molecules, which of those would show a strong IR absorption in that region?
Propyl gallate because it is the only one with O=C-O within its structure
SERS is a special version of ["Raman Spectroscopy", "Near-Infrared Spectroscopy", "Mid-Infrared Spectroscopy", "Nuclear Magnetic Resonance Spectroscopy"] that utilizes nanostructures on a gold or silver surface to enhance the ["Raman", "diffuse", "Raleigh"] scattering, and thus, increasing the signal.
In IR, wavelengths between ["0.38 to 0.75", "750 to 3750", "0.7 to 100"] μm are typically used:
["shorter wavelengths", "longer wavelengths"] between 2.5 to 15 μm being used in MIR
["longer wavelengths", "shorter wavelengths"] between 0.7 to 2.5 μm being used in NIR.
-Raman spectroscopy
-Nanostructures
-Raman
-0.7-100
-Longer wavelengths
-Shorter wavelengths
Quantitation of anthocyanin at 280 nm
UV spectroscopy
Lactose, protein, and fat content of milk
MIR spectroscopy
Protein in barley, oats, etc acc. to AACC
NIR spectroscopy
An antigen is any molecule that induces the formation of antibodies, and can bind to these antibodies. True or false?
True
collection of different antibodies that bind different epitopes on the antigen
polyclonal antibodies
the specific region on the surface of the antigen molecule bound by a single antibody binding site
epitope
a carrier protein-linked hapten
conjugate antigen
detection of molecules that are linked to a label to directly measure the amount of antibody or antigen
Direct immunoassay
involves an indicator reaction and a measuring reaction
Coupled reactions
Western blot is a laboratory-based immunoassay that combines PAGE and immunoassay to reveal the presence and ["concentration", "wavelength", "molecular mass"] of the antigenic protein on a membrane.
The major difference between Western blot and ELISA is that a positive reaction signal of ELISA indicates the presence of the antigen in a solution, while the positive signal of ["Western Blot", "ELISA"] indicates both the presence and molecular mass of the antigen.
In addition, ELISA allows the detection of antigen bound to the antibody with either a linear or ["circular", "non-linear", "conformational"] epitope. Western blot only allows the detection of antigen bound to its antibody with a ["non-linear", "conformational", "linear"] epitope.
-PAGE
-molecular mass
-ELISA
-western blot
-conformational
-linear
Common applications of immunoassays in food analysis include:
-authentication of fish species
-identification of food-borne pathogens
-detection of GMOs
-pesticide residue analysis
-allergen detection
According to the FDA (Links to an external site.) what are the 8 most common allergenic foods?
-Fish
-Crustacean shellfish
-tree nuts
-peanuts
-soybeans
-wheat
-eggs
-milk
What is the formula for proximate analysis? Define each term.
100%= %moisture+ %protein+ %lipids+ %carbs+ %ash
%moisture= water present in the food
%protein= amount of protein present in the food
%lipids= amount of fat present in the food
%carbs= amount of carbs/sugars present in the food
%ash= amount of all other misc. components within the food
How can you measure the precision of an experiment? Include the formulas and define each term.
Precision is measured using the coefficient of variation or standard deviation.
x=individual measure
x bar= mean
n=sample size (when n<25)
Coefficient of variation= (standard deviation/mean)*100
What is an enzyme? How does it affect the rate of a reaction?
An enzyme is a biological catalyst. It speeds up the rate of a reaction.
What is the substrate we will be using to determine enzyme activity in part 2 of Lab 2:Enzymes?
We will be using the reactant "IQ" which we can use to determine enzyme activity as it is a product of the reaction. It is measured using a spectrophotometer at 475nm
Name 4 of the "Big 8" allergens
-soy
-milk
-eggs
-crustacean shellfish
What does the abbreviation ELISA stand for and what does it detect (carbs, protein, fat, calcium, vitamin, etc)?
Enzyme Linked Immuno sorbent assay. It detects for proteins. More specifically allergen proteins.
Applications of MIR spectroscopy
-Infrared analyzers of milk
-Official AOAC method for fat, protein, and lactose contents
-fat (ester group)
-Protein (amide group)
-Lactose (hydroxyl group)
Applications of NIR
-commonly used to measure moisture, protein and fat/oil
-commonly used for products from various industries (grain, meat, dairy products)
-online measurement systems available
Applications of Raman
-little or no sample prep for solid and liquid samples
- aqueous samples like water and alcohol are weak raman scatterers
-can measure sample in any transparent containers including packaging
-less complex spectrum of compound than MIR or NIR
YOU MIGHT ALSO LIKE...