Spectrophotometric Determination of Nucleic Acid Concentration

Question 1

The range of all possible EM radiation

Answer 1

Electromagnetic waves

Question 2

the spectrum of different wavelengths that eyes recognize as white

Answer 2

light

Question 3

Electromagnetic waves are of _____ and waves

Answer 3

photons

Question 4

Part of the EM spectrum that can be seen by the naked eye

Answer 4

visible spectrum

Question 5

which waves are in the right of the visible light in the spectrum, these are characterized to have longer wavelengths

Answer 5

infrared, microwave, and radiowaves

Question 6

t or f

shorter wavelengths are less harmful than longer wavelengths

Answer 6

F (high frequency, shorter wavelength = more harmful)

Question 7

which waves are found at the left of visible light, these are characterized to have a higher frequency

Answer 7

gamma ray, x-ray, and ultra violet rays

Question 8

Should we be more wary of waves that are higher or lower in frequency?

Answer 8

higher frequency (shorter waves)

Question 9

an optical instrument for measuring the intensity of light in any specific wavelength related to solution concentrations

Answer 9

spectrophotometer

Question 10

In what section of the lab are spectrophotometers used to measure the concentration of an analyte

Answer 10

clinical chemistry

Question 11

T or F

spectrophotometers enable for a qualitative analysis of the substance only

Answer 11

F (quali and quanti)

Question 12

Before measuring the analyte using a spectrophotometer, what do you measure first for control purposes?

Answer 12

blank / reference cell

Question 13

What should be the result of the blank or reference cell?

Answer 13

zero

100% transmittance and 0% absorbance

Question 14

the measure of the capacity of a substance to absorb light of a specific wavelength

Answer 14

absorbance / optical density

Question 15

the measure of how much light passes through a substance

Answer 15

Transmittance

Question 16

what formula is this for?

Answer 16

transmittance

Question 17

what formula is this for?

Answer 17

Absorbance

Question 18

A mathematic relationship that is the basis of analysis in spectrophotometry

Answer 18

beer’s law

Question 19

T or F

In beer’s law, the concentration of the substance is inversely proportional to the amount of light absorbed

Answer 19

F (proportional)

directly proportional

Question 20

T or F

Beer’s law states that the concentration of the substance is inversely proportional to the logarithm of transmitted lights

Answer 20

T

Question 21

this produces intense reproducible constant beam of light, where everything starts

Answer 21

light source

Question 22

T or F

White light contains all of the wavelengths

Answer 22

T

Question 23

What is the type of light source for UV region

Answer 23

deutrium lamp

Deutrium (high-pressure hydrogen) lamp

Question 24

what is the most common light source for visible and infrared rays regions

Answer 24

Tungsten - halogen

Question 25

What is the component of the spectrophotometer that makes it so that all of the light beams are parallel to each other

Answer 25

collimator

Question 26

This is a system for isolating radiant energy of a desired wavelength and excluding that of other waves

Answer 26

monochromator / diffraction grating

Question 27

T or F

When you change the light source, the machine should be calibrated

Answer 27

T

Question 28

Why should you recalibrate the machine when you change the light source?

Answer 28

because the angle of the light shining in the monochromator also changes

Question 29

T or F

the monochromator flashes all of the wavelengths

Answer 29

F (you can select the specific wavelength of your chosen analyte)

Question 30

T or F

prisms achieve dispersion due to the difference in the material refracted index according to its wavelength

Answer 30

T

Question 31

What does diffraction grating use to split the light?

Answer 31

difference of diffraction direction due to interference

Question 32

prism or diffraction grating?

can be made to spread colors over a larger angle

Answer 32

diffraction grating

Question 33

prism or diffraction grating?

more sensitive to the color of the light

Answer 33

prism

Question 34

A small vessel used to hold a liquid sample to be analyzed in a spectrophotometer

Answer 34

Cuvettes

Question 35

What shapes do cuvettes come in?

Answer 35

round, square, or rectangular

Question 36

What materials are cuvettes constructed from?

Answer 36

glass, silica, or plastic

Question 37

What type of cuvette is used for UV range

Answer 37

quarts

Question 37

Why do we discard the cuvette if it becomes scratched?

Answer 37

the scratch can affect the spectrophotometer reading

the light bounces of the scratches :((

Question 38

what type of cuvette for visible range

Answer 38

glass

Question 39

converts light energy (transmitted by a solution) to an electrical signal

Answer 39

photodetectors

Question 40

simplest photodetectors

Answer 40

photocell and phototube

Question 41

commonly used photodetector for measuring light intensity in the UV and visible region, it’s rapid and very sensitive

Answer 41

photomultiplier tube (PMT)

Question 42

An electrical energy coming out from a detector is displayed on some type of digital display or readout system

Answer 42

readout device

Question 43

in what forms can a readout be

Answer 43

chart, digital display, or a computer printout

Question 44

What are the 2 applications of spectrophotometer

Answer 44

1. Measurement of concentration
2. Detection of impurities

Question 45

Why does nucleic acids absorb uv light

Answer 45

due to the presence of heterocyclic rings in the bases

Question 46

what is the wavelength of maximum absorption for both DNA and RNA

Answer 46

260 nm

Question 47

which characteristic is used to quantify the amount of nucleic acids

Answer 47

amount of absorbed light

Question 48

Wavelength of maximum absorption for detecting proteins and salts

Answer 48

• 280nm - proteins
• 230nm - salts