Nucleic Acids Flashcards
describe general structural parts:
type of bond?
contains:
- purine of pyrimidine base attached to pentose by beta glycosidic bond.
- phosphate is attached to pentose by phospho-ester bond
describe phosphate group
neg charged at neutral pH. ionized
attached to C5 on pentose ring by a phospho-ester bond
what are nucleobases?
derivatives of pyrimidine or purine
nitrogen containing
planar
absorbs UV light (250-270nm)
what are nucleotides?
pentose + phosphate + nitrogenous base
linkage of nucleotide polymerization?
phosphodiester linkage between 5’ end of sugar and 3’ end of sugar of next nucleoside
5’ ends are phosphorlyated
3’ ends are not
how are DNA/RNA polyers written?
5’ to 3’
what did Griffith’s experiment conclude?
nucleic acids are responsible for transfer of genetic material
what did avery McLeaod McCarty experiment conclude?
transforming factor is NA
Conclusion of Hershey and Chase bacteriophage infection experiment?
The injected material from the Bacteriophage was 32P (radioactive) labelled. Was injected into bacterial cell and blended. The result is that one cell is radioactive and the other is not radioactive
NAs are responsible for the storage and transferred of genetic materia
of bonds between AT and CG?
AT = 2 H bonds
CG = 3 H bonds
what is chargaffs rule?
A+G = T+C
is the double helix right or left handed?
what kind of grooves does it have?
right handed
both, major and minor
where do the phosphate groups point? where do bases point?
phosphate: point outside
bases: stacked and point inside
width of double helix?
20armstrongs. (2nm)
approx 3armstrongs between adjacent bases
what holds together bases?
h bonds and can der waal interactions
how far away are bases seaparated from each other along helix axis?
width of pitch of helix?
how many nucleotides per helix turn?
3.4armstrong (0.34nm)
36 armstrong (3.6nm). therefore 10.4 nucleotides per helix turn
helix is made up of two…
antiparallel but complimentary strands
DNA to RNA is what?
RNA to protein is what?
transcription
translation
what are the 3 postulated methods of DNA replication?
semi conservative
conservative
dispersive
describe. refer to diagram
why is conservative replication not biologically significant?
no genetic variety.
show effects of only conservative replication from meselson stahl experiment
what does the meselson stahl experiment conclude?
confirmed that DNA replication is semi conservative
is DNA replicated uni or bi directionally?
bi
characteristics of DNA poly 1
catalyzes addition of nucleotides 5’ to 3’
role of single strand binding proteins?
keeps DNA strands separate
role of topoisomerase?
releases stress of DNA unwinding through transient DNA cut and ligation
role of primase?
doesn’t need free k’OH group to add complimentary base pairs (which is needed for leading strand and lagging strand replication)
role of primase?
doesn’t need free k’OH group to add complimentary base pairs (which is needed for leading strand and lagging strand replication)
puts the first nucleotide. then RNA primer provides 3’ end for polymerase to build up and copy
what are okazaki fragments
short DNA fragments complimentary to legging strand sequence
describe exonuclease activity of DNA polymerase 1
removes RNA primer by 5’3’
role of DNA ligase?
joins DNA fragments on lagging strand
describe DNA denaturation and renaturation?
what affects the temperature at which DNa is denatured?
2 steps: slow (rate limiting) and rapid phases
ionic strength of DNA solution affects temp of denaturing
N bases of nucleosides or nucleotides are linked to the ribose ring by what kind of bond?
covalent and N-glycosidic bond
in RNA polymer, the ribose rings in polymer are linked to one another by…
phosphodiester linkage and sensitive base labile linkage
What property of the double helix did watson and crick predict based on chargaffs rule? A. The N-bases are pointing inward B.A copying mechanism C.Sensitivity to base hydrolysis D.Distance between the bases in helix E.A and B
B. coping mechanism
