fundamental techniques

Question 1

light scattering

Answer 1

aka photocorrelation spectroscopy

This method can determine size distribution of particles in a suspension

If the particles aren’t round also need to consider rotational Brownian motion effects on scattering

Question 2

xray diffraction

Answer 2

one application in crystallography

need to use braggs law n*lambda = 2d sin(theta)

to related xray diffraction pattern to 3d locations of particles

need less than 1.5A for good results but can get up to 1A resolution

Question 3

neutron diffraction

Answer 3

can get up to 2A resolution
used to identify location of hydrogens and waters.
Can swap H and deuterium to identify solvent accesibility and macromolecular dynamics

problem is requires large beams or long exposure
Complementary to both NMR and xray diffraction

Question 4

multiphoton microscopy

Answer 4

used for imaging living cells from molecular to organismal level

Can image deeper since it uses near ifrared lasers

Question 5

confocal microscopy

Answer 5

a very narrow beam of light to penetrate the sample at different levels
Can build 3D models

both live and dead cells

Question 6

scanning electron microsocpe

Answer 6

detects surface topology.

Similar to TEM but only surface topology

Question 7

diffracion limit

Answer 7

resolution =(wavelength)/(numerical aperature size)

For optics today its about
Resolution=lambda/2.8

Question 8

atomic force microscopy

Answer 8

resolution in angstroms

can resolve the topology
or do pulling

Question 9

diffracion limit

Answer 9

resolution =(wavelength)/(numerical aperature size)

optical limit abuot 1 microns

Question 10

sedimentation experimenets

Answer 10

can identify mass and molecular weight of sample

detect amount of aggregates

determining size of proteins native state (monomer vs trimer, vs dimer etc)

determining shape of molecule

detect change in conformation of protein

study formation and stoichiometry of complexes (receptor-ligand or antigen-antibody)

Question 11

types of absorption spectroscopy

Answer 11

*xray : excitation of inner shell
*uv-vis
IR
microwave
radiowave (electron spin resonance and NMR)

Question 12

Fraunhofer lines

Answer 12

absoprtion spectra lines each one representing an element (although some represent the lines in the hydrogen atom Balmer series)

Question 13

Balmer series

Answer 13

spectral lines of the hydrogen atom (4 in visible spectrum, 2 in UV)
- for tranisition from n>2 to n=2 orbital

Question 14

Energy difference between orbitals

Answer 14

E-E0= -Rhc*(1/n2^2 - 1/n1^2)

Question 15

Lyman series

Answer 15

lines for transmission from n>1 to n=1 orbital

Question 16

xray absoprtion spectroscopy

Answer 16

determines local geometric and electronic structure

Question 17

UV VIS absorption spectroscopy

Answer 17

detemrine chemical kinetics

Question 18

IR absorption spectroscopy

Answer 18

vibrational spectroscopy

IR is absorbed at resonant frequencies
measures changes in dipole moment

Question 19

microwave spectroscopy

Answer 19

rotational spectrosopy

Question 20

microwave spectroscopy

Answer 20

rotational spectrosopy

measures how dipole interacts with EM field

microwaves cause changes between 5 rotational modes
diatomic, linear, spherical, asymmetric tops, and symmetric tops

Question 21

electron spin resonance spectroscopy

Answer 21

unpaired electrons are measured
detects transitions in a magnetic field

spins splitting based on rules

can probe structural properties such as those for Vimentin

Question 22

Nuclear magnetic resonance

Answer 22

changes to nuclei in magnetic field

can determine structure and dynamcis of proteins and nucleic acids

Question 23

fluorimetry

Answer 23

You can attach a flurophore to a species or part of a cell

Then you shine light to excite it and cause it to fluresce, From there you track what is happening in time and space

tryptophan fluorescence in proteins too!

can track how proteins are folding

Question 24

Raman spectroscopy

Answer 24

uses monochromatic light

identifies molecules, chemical bonds, and intramolecular bonds

Also study substarte to an enzyme

used to confirmed low frequency phonons in proteins and DNA