DNA is wrapped tightly around histones and coiled tightly to form chromosomes DNA had specific pairing between the nitrogen bases: ADENINE – THYMINE CYTOSINE - GUANINE DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule” DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of tiny subunits called Nucleotides. Each nucleotide consists of: Phosphate group Pentose sugar Nitrogenous base The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. DNA has a diameter of only 0.000000002 m.

2.  DNA is the genetic code,
 Instructions for heredity,
 Components of genes,
 Director of protein synthesis
 A type of nucleic acid
 A type of organic compound
 A polymer {a compound made of repeating
subunits}

5.  Discovery of the DDNNAA ddoouubbllee hheelliixx
A. Frederick Griffith – Discovers that a
factor in diseased bacteria can transform
harmless bacteria into deadly bacteria
(1928)
B. Rosalind Franklin - X-ray photo of DNA.
(1952)
C. Watson and Crick - described the
DNA molecule from Franklin’s X-ray.
(1953)

6. •DDNNAA hhaadd ssppeecciiffiicc ppaaiirriinngg bbeettwweeeenn tthhee
nniittrrooggeenn bbaasseess::
AADDEENNIINNEE –– TTHHYYMMIINNEE
CCYYTTOOSSIINNEE -- GGUUAANNIINNEE
•DDNNAA wwaass mmaaddee ooff 22 lloonngg ssttaannddss ooff
nnuucclleeoottiiddeess aarrrraannggeedd iinn aa ssppeecciiffiicc wwaayy
ccaalllleedd tthhee ““CCoommpplleemmeennttaarryy RRuullee””

7. DNA consists of two molecules that are arranged
into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of
tiny subunits called Nucleotides.
Each nucleotide consists of:
1. Phosphate group
2. Pentose sugar
3. Nitrogenous base

8. Phosphate
Pentose
Sugar
Nitrogenous
Base

9. The phosphate and sugar form the backbone of
the DNA molecule, whereas the bases form the
“rungs”.
There are four types of nitrogenous bases.

10. A
Adenine
T
Thymine
G
Guanine
C
Cytosine

11.  Pyrimidines are
single ring bases.
 Purines are
double ring
bases.
11
C
C
C
N
C
N
OO
N
C
C
C
C
N
N
N
N
N
C

12. Each base will only bond with one other specific
base.
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Form a base pair.
Form a base pair.

13.  A=T – double hydrogen
bond
 G C – triple hydrogen
bond
 Nucleotide (3 chemical
groups)
 Sugar – deoxyribose
 contains 5 Carbon atoms
 Phosphate group
 A base (A, T, G, C)

14. ““RRuunnggss ooff llaaddddeerr””
NNiittrrooggeennoouuss
BBaassee ((AA,,TT,,GG oorr CC))
““LLeeggss ooff llaaddddeerr””
PPhhoosspphhaattee &&
SSuuggaarr BBaacckkbboonnee

15. Major Features of DNA Double Helix:
1. Two polynucleotide chains coil together to
form right-handed helix.
2. The two chains are anti-parallel; both run from
5’ to 3’ but their orientations are opposite.
3. The nitrogen bases of opposite chains pair to
one another and form H bonds:
G – C and A – T

16. 4. The base pairs stack on each other and located
on the inside of the helix.
5. Each complete turn of DNA is 3.4nm long and
contains 10 bases.
6. Each turn along the molecule contains one major
grove and one minor grove.

18.  AAddeenniinnee must pair with TThhyymmiinnee
 GGuuaanniinnee must pair with CCyyttoossiinnee
 Their amounts in a given DNA molecule will
be aabboouutt tthhee ssaammee.
T A G C

19. H-bonds
G C
T A

20. Because of this complementary base
pairing, the order of the bases in one
strand determines the order of the
bases in the other strand.

21. T
G
A
G
T
A
A
C
T
C
A
G
T
C

22. To crack the genetic code found in DNA we need
to look at the sequence of bases.
The bases are arranged in triplets called codons.
A G G - C T C - A A G - T C C - T A G
T C C - G A G - T T C - A G G - A T C

23.  A gene is a section of DNA that codes for a protein.
 Each unique gene has a unique sequence of bases.
 This unique sequence of bases will code for the
production of a unique protein.
 It is these proteins and combination of proteins that
give us a unique phenotype.

24.  DNA must be copied
 The DNA molecule produces 2
IDENTICAL new
complementary strands
following the rules of base
pairing:
A-T, G-C
•Each strand of the
original DNA serves as a
template for the new
strand

25.  Semiconservative Model:
1. Watson and Crick showed:
the two strands of the parental
molecule separate, and each
functions as a template for
synthesis of a new
complementary strand.
Parental DNA
DNA Template
New DNA

26.  DNA has a lagging
strand 3’-5’ and a
leading strand 5’-3’
 The 5’ end matches with
a 3’ end in a double
helix
 DNA replication occurs
every 20 minutes in E.
coli (widely used to
reproduce DNA)
 Copying DNA molecule
 Each DNA strand
(double helix) unzips
itself
 Happens before cell
division (mitosis and
meiosis)
 Done in PCR
(polymerase chain
reaction) to make a lot
of the same DNA (mass
replication) for analysis
through fingerprinting.

28. Protein
DNA
Gene
Trait

29.  DDNNAA ffrroomm aa ssiinnggllee hhuummaann
cceellll eexxtteennddss iinn aa ssiinnggllee
tthhrreeaadd ffoorr aallmmoosstt 22 mmeetteerrss
lloonngg!!!!!!
 IItt ccoonnttaaiinnss iinnffoorrmmaattiioonn
eeqquuaall ttoo ssoommee 660000,,000000
pprriinntteedd ppaaggeess ooff 550000 wwoorrddss
eeaacchh!!!!!!
((aa lliibbrraarryy ooff aabboouutt 11,,000000 bbooookkss))

30.  The average human has
75 trillion cells.
 The average human has
enough DNA to go
from the earth to the
sun more than 400
times.
 DNA has a diameter of
only 0.000000002 m.
30
The earth is 150 billion m
or 93 million miles from
the sun.

31.  Electrophoresis separates DNA and Proteins
using electricity through a porous material.
Movement of the DNA and Protein is a
function of size.
•DNA speed is based on size.
•Smaller is Faster and Bigger is slower.
 It’s like McDonalds on a busy weekend.

32. Autoradiography
Radioisotopes Intercalating Dyes
Ethidum Bromide