NMR and DNA Sequencing Quiz

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Questions and Answers

Why is fluorescence widely applied in DNA sequencing?

Some dyes strongly decrease their fluorescence signal upon binding to DNA

Many dyes easily bind to DNA

Some dyes highly increase their fluorescence quantum yield upon binding to DNA (correct)

Some dyes highly increase their absorption upon binding to DNA

What range of frequencies is typically utilized by medical ultrasound?

Above 100 kHz but below 20,000 kHz (correct)

Above 20 MHz

Below 100 kHz

Below 20 kHz but above 20 Hz

If a 4 Tesla magnet produces EM radiation of about 300 MHz, what frequency will an 8 Tesla magnet produce with its field directed opposite?

300 MHz (correct)

600 MHz

900 MHz

150 MHz

What is the frequency at 7.05T if 13C in a 4.7T field has a frequency of 25.2?

50.4 Signup and view all the answers

What will the observed chemical shift be when the field strength is doubled from 5T to 10T with an initial shift of 6 PPM?

12 PPM Signup and view all the answers

Why is 13C used for NMR imaging?

Has more neutrons Signup and view all the answers

Which of the following statements accurately describes an acoustic wave?

Transverse wave Signup and view all the answers

In an energy diagram, identifying the higher energy state is crucial. Which state is correct?

Depends on frequency Signup and view all the answers

Why are atoms like 19F and 13C used in NMR?

They have one more neutron as compared to natural Signup and view all the answers

How does the speed of an ultrasound wave in tissue compare to that in air?

Higher Signup and view all the answers

What causes the chemical shift in NMR for different protons?

Shielding of the magnetic field by electrons of various surrounding groups Signup and view all the answers

What is the correct definition of isotopes?

Same number of protons and different number of neutrons Signup and view all the answers

If a magnet of 3 Tesla results in EM radiation of about 300 MHz, what radiation will a 9 Tesla magnet produce?

600 MHz Signup and view all the answers

Which statement best describes isomers?

Molecules with same chemical formula but different spatial arrangement of atoms Signup and view all the answers

If the observed chemical shift for the 5T field was 6 PPM, what could it indicate?

A unique chemical environment Signup and view all the answers

What does a frequency of 500 MHz correspond to in terms of wavelength in air?

600 um Signup and view all the answers

What is the result of H1-H2 coupling in NMR?

Multiple lines in NMR Signup and view all the answers

What causes emission depolarization?

Fast rotational mobility of molecules in the solution Signup and view all the answers

How is fluorescence lifetime best defined?

The time after population of molecules in the excited state increases e times Signup and view all the answers

What characteristic does a solvent-sensitive fluorophore exhibit?

Emission spectrum that depends on the fluorophore environment Signup and view all the answers

If a complex of two proteins dissociates, what happens to the emission anisotropy of a probe attached to one of them?

It will decrease Signup and view all the answers

What signifies the end of a fluorescence lifetime?

When the intensity of fluorescence decreases 10 times Signup and view all the answers

Which of the following is NOT a feature of emission from a fluorophore?

Independent of temperature Signup and view all the answers

Study Notes

DNA Sequencing and Fluorescence

Fluorescence is widely used in DNA sequencing due to dyes that increase fluorescence upon binding to DNA.

NMR Frequency and Magnetic Field Strength

The frequency of ¹³C in a 4.7T magnetic field is 25.2.
In a 7.05T field, the corresponding frequency will be 50.4.

NMR Isotope Use

¹³C is used for NMR imaging because it is not naturally occurring.
It is not stable and its decay can be observed
It has a lower molecular mass.

Energy States

In the provided diagram, state B has a higher energy than state A.

NMR Atom Use

¹⁹F and ¹³C atoms are used in NMR because they have different numbers of neutrons.

Chemical Shift in NMR

Chemical shift differences in NMR are caused by interactions with solvents and shielding of the magnetic field by surrounding groups, electrons or protons.

NMR Radiation

A 3 Tesla magnet produces 300 MHz EM radiation.
A 9 Tesla magnet will produce 900 MHz radiation.

Chemical Shift Change

If a 5T field gives a 6PPM chemical shift, doubling the field to 10T will produce a 12 PPM shift.

Acoustic Waves

Acoustic waves are transverse waves.

Ultrasound Speed

Ultrasound speed in tissue is lower than that in air.

Isotopes

Isotopes are forms of an element with the same number of protons but a different number of neutrons.

Isomers

Isomers are molecules with the same chemical formula but different spatial arrangements of atoms.

NMR Wavelength

A 500 MHz NMR will produce a 600 mm wavelength.

H1-H2 Coupling

H1-H2 coupling produces multiple lines in NMR.

Emission Depolarization

Emission depolarization occurs due to the fast rotational mobility of molecules in solution .

Fluorescence Lifetime

The fluorescence lifetime is the time it takes for the initial fluorescence intensity to decrease to half its value. The fluorescence lifetime varies from the shortest time in which a molecule can stay in the excited state to the longest time it can stay.

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Description

Test your knowledge on the principles of fluorescence in DNA sequencing and the use of NMR in studying isotopes and energy states. This quiz covers topics from magnetic field strength to chemical shifts. Perfect for students in chemistry and biophysics courses.