DNA structure

1.  DNA is often
called the
blueprint of life.
 In simple terms,
DNA contains the
instructions for
making proteins
within the cell.

2. We study DNA forWe study DNA for
many reasons:many reasons:
 its centralits central
importance to allimportance to all
life on Earthlife on Earth
 medical benefitsmedical benefits
such as cures forsuch as cures for
diseasesdiseases
 better foodbetter food
crops.crops.

3.  ChromosomesChromosomes
are made up ofare made up of
genes.genes.
 Genes areGenes are
made up of amade up of a
chemical calledchemical called
DNA.DNA.

4.  DNA is a veryDNA is a very
long molecule.long molecule.
 The basic shapeThe basic shape
is like a twistedis like a twisted
ladder or zipper.ladder or zipper.
 This is called aThis is called a
double helix.double helix.

5.  The backbone ofThe backbone of
the molecule isthe molecule is
alternatingalternating
phosphatephosphate andand
deoxyribosedeoxyribose, a, a
sugar, parts.sugar, parts.
 The teeth areThe teeth are
nitrogenousnitrogenous
basesbases..
phosphate
deoxyribose
bases

6.  The DNA doubleThe DNA double
helix has twohelix has two
strands twistedstrands twisted
together.together.
 (In the rest of(In the rest of
this unit we willthis unit we will
look at thelook at the
structure of onestructure of one
strand.)strand.)

8.  DNA is located in
the nucleus

9.  The code of life

10. C C
C
O
Phosphate
O
C
C
O -P O
O
O
O -P O
O
O
O -P O
O
O
Nitrogenous
base
Deoxyribose

11.  Each side of the
ladder is made up
of nucleic acids.
 The backbone is a
phosphate and a
sugar
 The rung of the
ladder is the
nitrogen base.

12.  When makingWhen making
hydrogen bonds,hydrogen bonds,
cytosine alwayscytosine always
pairs up withpairs up with
guanine,guanine,
 And adenineAnd adenine
always pairs upalways pairs up
with thymine.with thymine.
 (Adenine and(Adenine and
thymine arethymine are
shown here.)shown here.)
C
C
C
C
N
N
N
N
N
C
C
C
C
C
N
N
OO
OO
C

13.  CytosineCytosine CC
 ThymineThymine TT
 AdenineAdenine AA
 GuanineGuanine GG
DNA has four different bases:DNA has four different bases:

14.  Remember, DNARemember, DNA
has two strandshas two strands
that fit togetherthat fit together
something like asomething like a
zipper.zipper.
 The teeth are theThe teeth are the
nitrogenousnitrogenous
bases but why dobases but why do
they stickthey stick
together?together?

16.  A= adenine
 G= guanine
 C= cytosine
 T= thymine

17.  Where is DNA
located?
 What does it look
like?
 What are its bases?
 What is bound
between of bases
and bound between
of nucleotide?