DNA 1 and 2 Flashcards
RNA stands for
ribonucleic acid
DNA stands for
Deoxyribonucleic acid
what is responsible for storing and translating the information encoding each of the proteins and performing other chemistry
ribose-phosphate polymers
RNA is responsible for
enzymatically synthesizing all proteins
about how much of DNA is protein encoding
2%
how many monomers are found in each DNA set in the human cell
3x10^9
3 billion
total length of polymer of DNA in a cell
1 meter/cell
what two things contribute to errors
translation and transcription
in what organisms are mutation rates low
bacteria and humans
low mutation rate
1 per 1-^8or9
what organisms have a high mutation rate
viruses and cancers
high mutation rate
1 per 1000
why might a high mutation rate be a good thing?
it helps the virus evade the immune system.
makes cancer harder to treat
two types of bases
purines and pyrimidines
purines
adenine
guanine
pyrimidines
uracil
cytosine
thymine
how are bases linked to the ribose sugar
N-linked
via the nitrogen on the base
another name for a ribose sugar
furanose
what does ribose do in water
cyclizes and puckers
nucleoside
a base linked to a pentose sugar
NO PHOSPHATE
nucleotide
a base linked to a phosphate ester of a pentose
base, sugar and phosphate
base, nucleoside, nucleotide nomenclature for A
adenine
adenosine
adenylate
base, nucleoside, nucleotide nomenclature for G
guanine
guanosine
guanylate
base, nucleoside, nucleotide nomenclature for U
uracil
uridine
uridylate
base, nucleoside, nucleotide nomenclature for C
cytosine
cytidine
cytidylate
base, nucleoside, nucleotide nomenclature for T
thymine
thymidine
thymidylate
DNA at base pair levels form what kinds of bonds
hydrogen bonds
A and T/U form how many base pairs
2
C and G form how many base pairs
3
the hydrogen bonds between the bases make the DNA
flexible
in purines, where does the first nitrogen come from
aspartate
in purines where does the second carbon come from
N10-Formyl-tetrahydrofolate (THF)
in purines, where does the third nitrogen come from
glutamine
in purines, where does the 4th carbon come from
glycine
in purines where does the 5th carbon come from
glycine
in purines where does the 6th carbon come from
CO2
in purines where does the 7th nitrogen come from
glycine
in purines, where does the 8th carbon come from
N10-Formyl-tetrahydrofolate (THF)
in purines where does the 9th nitrogen come from
glutamine
PRPP
5-phosphoribosyl-1-pyrophosphate
what is the activated donor of the sugar unit in biosynthesis of nucleosides using a phosphoribosyl transferase
PRPP
the purine rings are synthesizes on the
ribophosphate
what amino acid is needed to start the process of turning PRPP into a purine
glutamine
what is the initial purine made from the PRPP pathway
Inosinate (IMP)
hypoxanthine base
Inosinate (IMP) can be turned into
Adenylate (AMP)
Guanylate (GMP)
Free bases can be recycled and attatched directly in what is known as
a salvage reaction
how is a salvage reaction done
using a phosphoribosyl transferase reaction
the monophosphates are enzyme … for their own synthesis
inhibitors
AMP production from IMP is inhibited by
AMP
GMP production from IMP is inhibited by
GMP
IMP production from PRPP is inhibited by
IMP, AMP, and GMP
in pyrimidines where is the 1st nitrogen from
aspartate
in pyrimidines where is the second carbon from
carbamoyl phosphate
in pyrimidines where is the 3rd nitrogen from
carbamoyl phosphate
in pyrimidines where is the 4th carbon from
aspartate
in pyrimidines where is the 5th carbon from
aspartate
in pyrimidines where is the 6th carbon from
aspartate
aspartate and carbamoyl phosphate come together to make
orotate
orotate is used to make the precursor pyrimidine called
uridylate (UMP)
How is RNA reduced to DNA
by a ribonucleotide reductase known as ribonucleoside diphosphate reductase
DNA bases are aromatic and therefore
stack well
what provides specific pairing and form specific structed in salt water in reguards to DNA
hydrogen bonds
what do the major and minor groove in DNA do
hold water, ions, and provide many recognition sites for other molecules including proteins
duplex (ds) DNA is often characterized as
a nearly rigid charged rod
duplex DNA has a persistance length (P) of
500 A
single stranded DNA (or RNA) had a persistance length (P) of
less than 10 A
two ways to measure persistance length (P)
FRET and FCS
what packs the DNA in phages
ATP consuming motor
many of the common cofactors are also
nucleotides
three common cofactors
coenzyme A
NAD+
FAD
how many phosphates can be added onto a nucleoside
1, 2, or 3
synthesis and degradation of the bases are very
material and energy intensive reactions
de novo synthesis molecule for pyrimidines
UMP
end products for pyrimidine degredation
B-alanine and B-aminoisobutyric acid
B-aminoisobutyric acid smells like
old tennis shoes
de novo synthesis molecule of purines
IMP
end/waste product of purine degredation
uric acid
the synthesis cycles are dependent on
energy molecules
AMP synthesis depends on
GTP
GMP synthesis depends on
ATP
essentially any -OH on the furanose ring could be substituted with
phosphates
3’ and 5’ OH substitutions on the furanose ring are for
the backbone
2’ and 3’ OH substitutions on the same furanose ring make
a Cyclic NMP molecule used in secondary messenger pathways
given the number of rotatable bonds, the number of conformations per base is
large meaning there is lots of flexibility
the glycosidic linkage at the base is called the
X dihedral
flagpole
syn
the base is turned toward the furanose ring
anti-
the base is turned away from the furanose ring
examples of less common bases
5-methylcytidine
N6-methyladenosine
N2-methylguanosine
5-hydroxymethylcytidine
inosine
pseudouridine
7-methylguanosine
4-thiouridine
the bases pair up specifically with H-bonds and yeild similar
C-1’ to C-1’ distances
differences between RNA and DNA
the OH in the backbone and the change of T for U
A problem with RNA stability
can be easily hydrolized on the 2’OH by water or OH
each base has a unique UV absorption spectrum due to
the electronic differences in the rings and substitutions
the bases have several titratable groups and as a result
several resonance tautomers exist
so pH plays a role
guanine tautomers
keto and enol
adenine tautomers
amine and imine
tautomers for pyrimidines
lactam, lactim and double lactim
tautomers cause what
mutations during replication and repair
different resonance states are allowed due to
the number of hetero atoms in conjuction in the rings
the absorption spectrum of the nucleic acids depends on
pH
nucleotide availability via synthesis is crucial to
dividing cells where a new copy of the chromosome is needed
nucleotide synthesis is a good candidate for
chemo therapeutics
an example of nucleotide synthesis for a target
dihydro-foliate reductase
folic acid
p-aminobenzoic acid
attractive forces in DNA
base pair hydrogen bonds
base pi stacking
repulsive forces in DNA
excluded volume
phosphate-phosphate repulsions
two charges q1 and q2 interact with each other by
coulomb’s law
The interaction between two charges can be changes by the presence of
excess salt (debye and Huckel)
dipoles align to oppose the
external field in dielectric screening
all biochemistry requires
salt water or buffers
liquid state order: solvation shells
when the molecules are tumbling in solution and there is salt, the system is not crystalline the distribution has structure but is not periodic like a lattice.
The electric fild around DNA changes the probability of finding
salt and other DNA
counter ions pile up near
a helix or between two helices
counter ions increase
the ionic strength and screening locally