Exam 1 review Flashcards
molecules recognize each other by
interactions
van der waals interactions
give strong repulsions, weak “flickering” attractions
dipole interactions
between molecules with hetero atoms
hydrogen bonds
a type of dipole interaction with hydrogen that is important in biology
strong interactions
covalent bonds and ionic interactions are responsible for stable, long-lived, structures
water is the
ultimate hydrogen bonding liquid
as ice, water forms how many bonds
4 h bonds
2 accept
2 donate
tetrahedral in shape
as a liquid water forms how many bonds
4.5 h bonds
makes liquid more dense than ice
life requires
water`
water properties
liquid solvent
concentration gradients
biopolymers adopt unique shapes
hydrogen bonding networks
tetrahedral bonding
large void volume, dissolution of gasses
liquid from 273K to 373K
density maxima
liquids and polymers are dominated by weak forces from potential interactions around RT in size. All of biology depends on using weak forces to allow
biological changes
the purine groups are synthesized on the
ribophosphate
PRPP
that displaces the phosphate at C1 on PRPP
the amide group of glutamine
where is RNA hydrolyzed by water or base
2’OH
RNA hydrolyzation creates
a 2’,3’ cyclic monophosphate nucleotide and a truncated RNA
each base has a unique UV absorption spectrum due to the
electronic differences in the rings and substitutions
for sequencing via UV, what wavelength is used
260nm
blue!
tautomers for pyrimidine bases
lactam
lactim
double lactim
tautomers are stabulized by different environments including
solvent polarity and pH
pH causes different H-bonds to be stable and can
change the UV spectrum
different electronic states are allowed due to the
number of hetero atoms in conjugation in the rings coupled to tautomers
pH differences for UV are more prevelant in
pyrimidines
in terms of the particle in a lox, pyrimidines have a
smaller box
greater % change
attractive forces in DNA stability
base pair hydrogen bonds
base pi stacking
repulsive forces in DNA stability
excluded volume
phosphate-phosphate repulsions
2 molecules q1 and q2 interact with each other by
coulombs law for the potential energy U
water diminishes (screens) the interactions between two charges via
the dielectric constant of 80
water divides the interactions between to charges by
80
excess salt further diminishes (screens) interactions between charges as found by debye and huckel meaning that
it goes exponentially to zero with ionic strength
right handed form of DNA
A and B
left handed form of DNA
z
diameter of A form
26 A
diameter of B form
20A