A ,B,C,Z DNA

1. Sasna.p.s

3.  1.RIGHT HANDED DOUBLE HELIX WITH
SHORTER AND MORE COMPACT HELICAL
STRUCTURE[wider and less flexible].
 2.CONDITION: 75% OF RELATIVE HUMIDITY &
na+,k+,cs+ ions.
 3. WHEN THE PUCKERING OF THE RIBOSE
UNIT CONCERNED C3 IS OUT OF THE PLANE
SO IT IS C3 ENDOPUCKERING

4.  4. HELIX DIAMETER :25.5 A*
 5.RISE PER BASE PAIR :2.3A*
 6.BASE PAIRS PER TURN OF HELIX :11
 7:HELICAL PITCH :25.30A*
 8.A DNA IS WIDER,LESS FLEXIBLE THAN B DNA IT CAN
INCORPORATE MORE BASE PAIRS PER HELICAL TURN
 9.PRESENCE OF MAJOR AND MINOR GROOVES.BUT
SLIGHT INCREASE IN THE NUMBER OF BASE
PAIR;RESULTING TIGHTER ROTATION ANGLE.AND
SMALL RISE PER TURN.SO MAJOR GROOVE IS NARROW
AND VERY DEEP. MINOR GROOVE IS VERY BROAD AND
SHALLOW

6.  1.THE TWO CHAIN IN THE DOUBLE HELIX ARE
ANTIPARALLEL [ones goes 5’-3’ where as
complementary strand goes 3’-5’]
 2.THE BASES ON THE 2 CHAINS PAIR IN A
COMPLEMENTARY FASHION ADENINE [A] PAIR
WITH THYMINE [T]. GUANINE[G] PAIR WITH
CYTOSINE[C]
 3.PHOSPHATE GROUPS ARE LINKED TOGETHER
THE SUGAR BACKBONE HAVE PHOPHODIESTER
BONDS

9. 4. HYDROGEN BONDS BETWEEN
BASES [3 FOR G-C, 2 FOR A-T] HOLD
HELIX TOGETHER
5. THERE ARE 10 BASE PER TURN OF
THE HELIX SO THE HELIX ROTATES 36
DEGREE PER BASE
6. THE RISE OF DOUBLE HELIX IS THE
DISTANCE PARELLEL TO THE AXIS OF
THE HELIX FROM THE LEVEL OF ONE
BASE TO THE LEVEL OF ADJACENT
BASE

10.  7.THE PITCH IN B- DNA IS 3.4 nm BECAUSE
THE RISE IS 0.34 nm AND THERE ARE 10 BASE
PAIRS PER TURN OF HELIX
 8.B-DNA IS FORMED AT THE RELATIVE
HUMIDITY 92% IN THE PRESENCE OF LOW ION
STRENGTH
 9.B-DNA POSSES MAJOR AND MINOR
GROOVES

13.  1.C-DNA IS FORMED AT THE RELATIVE
HUMIDITY 66% IN THE PRESENCE OF Li+ IONS
 2.RIGHT HANDED WITH AN AXIAL RISE OF
3.32A*
 3.9.33 BASE PAIRS PER TURNS OF THE HELIX
 4.HELIX PITCH IS 30.97A*

14.  5.THE ROTATIONS PER BASE PAIR IS 38.58
DEGREE
 6.HELIX DIAMETER IS 19A*
 7.MAJOR AND MINOR GROOVE IS ABSENT

16.  1.LEFT HANDED HELICAL ROTATION
[RICH,NORDHIEM AND WANG IN 1984]
 2.HEXA NUCLEOTIDE
 3.CGCGCG FORMS THE DUPLEX OF
ANTIPARRELLEL STRAND
 4.THE PHOSPHATES IN THE Z DNA BACKBONE
IS ZIG-ZAG MANNER HENCE THEY TERMED AS
Z-DNA

20. 5. ADJACENT SUGAR RESIDUE HAVE
ALTERNATING ORIENTATION
[REPEATING UNIT IS A DINUCLEOTIDE]
6.Z-DNA HAVE ONLY ONE DEEP
HELICAL GROOVE
7.Z-DNA INVOLVED IN REGULATION
OF GENE EXPRESSION,GENETIC
RECOMBINATION,

21. 8.Z-DNA SERVE AS A RECOGANITION
SIGNALS IN THE REGULATION OF
GENETIC TRANSCRIPTION AND DNA
REPLICATION.IT ALSO PLAY A ROLE
IN GENE CONVERSION AND GENETIC
INSTABILITY
9.Z-DNA IS FORMED AT VERY HIGH
SALTCONCENTRATION

24. CHARACTERISTIC A-DNA B-DNA C-DNA Z-DNA
CONDITIONS 75% OF
RELATIVE
HUMIDITY;K+
Na+,Cs+ IONS
92% RELATIVE
HUMIDITY ;LOW
ION STRENGTH
60% RELATIVE
HUMIDITY ;Li+
IONS
VERY HIGH SALT
CONCENTRATI-
ON
SHAPE BROADEST INTER MEDIATE NARROW NARROWEST
HELIX SENSE RIGHT
HANDED
RIGHT HANDED RIGHT HANDED LEFT HANDED
HELIX DIAMETER 25.5 A* 23.7 A* 19.0 A* 18.4 A*
RISE PER BASE
PAIR(h)
2.3 A* 3.4 A* 3.32 A* 3.8 A*
BASE PAIRS PER
TURN OF
HELIX(n)
11 10.4 9.33 12(=6 DIMER)
HELIX PITCH(hXn) 25.30 A* 35.36 A* 30.97 A* 45.60 A*

25. CHARACTERISTICS A DNA B DNA C DNA Z DNA
ROTATION PER
BASE PAIR
+32.72 +34.61 +38.58 -60(PER
DIMER)
BASE PAIR PER TILT 19 DEGREE 1 DEGREE _ 9 DEGREE
GLYCOSIDIC BOND ANTI ANTI _ ANTI FOR
C-T
SYN FOR
A-G
MAJOR GROOVE NARROW
AND VERY
DEEP
WIDE AND QUITE
DEEP
_ FLAT
MINOR GROOVE VERY BROAD
AND
SHALLOW
NARROW AND
QUITE DEEP
_ VERY
NARROW
AND DEEP