Spectrophotometry Flashcards
A ________ is used to provide a source of light at certain energy, _______, and to measure the quantity of light that is absorbed by the sample.
Spectrophotometer, wavelength
______ is the amount of light that has been absorbed by the sample; and the relationship between sample concentration and absorbance is _____ up to a certain concentration.
Whereas, ____ is the fraction of incident light that passes completely through the sample; and the relationship between the sample concentration and transmittance is _________
Absorbance
Linear (directly proportional)
Transmittance
Exponential (inversely proportional)
A spectrophotometer is designed to detect _________ of light at different __________when the light passes through a solution of some given concentration.
Absorbance, wavelength
A spectrophotometer is a method of analyses that involves how _______ interacts with the atoms (or molecules) in a sample of matter.
Light
The _______ spectrum consists of electromagnetic radiation whose wavelengths range from 400 nm to nearly 800 nm.
Visible
When this light passes through a substance, certain energies (or colours) of the light are _____ while other colour(s) are allowed to pass through or are _______ by the substance.
Absorbed
Reflected
A substance appears white if it does not absorb ________
Any colour
We see _____ colour when the substance doesn’t absorb any white light.
White
We see ______ colour when the substance does absorb all colours except red colour
Red
The visible range is from ______ nm.
400 - 780
The ultraviolet range is ______ nm.
Below 400
The visible light is used to detect _____ substances, whereas the ultra-violet is used for ______ substances.
Coloured
Colourless
A ______ is either a prism or a diffraction grating that seperates the white light into all colours of the visible spectrum
Monochrometer
A _____ Lamp is used for Vis spectrophotometer
Tungstin
A _______ Lamp is used for UV spectrophotometer
Deuterium/Hydrogen/Mercury
Conjugated aromatic compounds, such as aromatic amino acids absorb _______ radiation
Ultraviolet
Compounds that absorb UV radiation are normally measured in cuvettes made of _______
Quartz
What is the optimum pH of pepsin?
2 or 3
The enzyme’s theory that state that “Enzyme structure is flexible, not rigid substrate binding induces appropriate conformational changes in the enzyme Increases range of substrate specificity.” is termed: ————————.
Induced-fit theory
The enzyme’s theory that state that “The shape of the active site is complementary to that of the substrate molecule.” is termed: ————–.
Key-Lock theory
What is the optimum pH of trypsin?
8
In non competitive inhibitors, the inhibitor fits into ————– site
allosteric
In non competitive inhibitors, the inhibitor fits into _______ site
Active site
The extinction coefficient of a solution containing 1g molecule of solute per 1 liter of solution is termed _______
Molar absorptivity or molar extention coefficient
The maximum ———is the one at which a compound gives its highest absorbance.
Wavelength
The slope of a standard curve divided by the cuvette’s path length is equal to _________
Molar absorptivity of molar extention coeficient
The equation for Beers-Lambert law is _______
A = (wierd E boi) x C x L
The cuvette with a path length of 0.4 cm gave an absorbance of 0.6. What is the absorbance when the path length is doubled?
1.2
Best results for unknown concentration is obtained when the absorbances are between ———–
0.1 - 1.0
The molar absorptivity deviates at concentrations
> 0.01 M
The enzyme’s uses the process termed “______ “to (i) prevent waste of cell raw materials (substrates), (ii) prevent overproduction of cell products and (iii) prevent wastes of cell energy
“switching on/off”
The ability of a compound to absorb light is termed _________
Molar absorptivity or molar extinction coefficient
Conjugated aromatic compounds such as aromatic amino acids are absorbed at which spectra?
Ultra violet
According to Beers-Lambert law, the relationship between the absorbance and transmittance is ______ proportional
Indirectly
The relationship between the absorbance and transmittance is __________
A = 2 - Log %T
or
A = Log (1/T)
—— light is actually a mixture of all the colors of light.
White
