August 7, 2015
Bell Work:
 True or False: All living organisms have
DNA.
Objective:
The student will be able to…
1. Explain his or her knowledge of DNA.
2. Define DNA
Today in History
 1912
The Progressive Party nominated
Theodore Roosevelt for president.
 1971
Apollo 15 returned to Earth after a
manned mission to the moon.
Contact Info
What do you know about
DNA?
DNA
 By
the 1950s most scientists were
convinced that genes were composed of
DNA
 DNA:
Deoxyribonucleic Acid
Watson and Crick
 James
Watson and Francis Crick were
researchers at Cambridge University
 They
were the first to piece together a
model of the structure of DNA
 The
discovery of the structure of DNA was
important because it clarified how DNA
could serve as the genetic material.
Watson and Crick
 Watson
and Crick determined the DNA was
a double helix
 Two
strands twisted around each other
 Similar
to a winding staircase
DNA Double-Helix
DNA Structure Worksheet
DNA Structure
 Each
helix is made of linked nucleotides
 Each
nucleotide is composed of three
groups
A
phosphate group
A
five carbon sugar molecule
A
nitrogen containing base
DNA Structure
 The
five carbon sugar is known as deoxyribose
 The
sugar molecule and the phosphate group are the same
for each nucleotide in a molecule of DNA
 There
are four different nitrogen bases
 Adenine
(A)
 Guanine
(G)
 Cytosine
(C)
 Thymine
(T)
DNA Structure
 Purines:
nitrogen bases made up of two rings of
carbon and nitrogen atoms
 Adenine
 Guanine
 Pyrimidines:
nitrogen bases made up of a single
ring of carbon and nitrogen atoms
 Thymine
 Cytosine
DNA Structure
 Base
pairing rules: A purine always pairs
with a pyrimidine
 Adenine
pairs with Thymine
 Guanine
pairs with Cytosine
Nucleotide Base Pairing
DNA Structure
 Adenine
forms two hydrogen bonds with
Thymine
 Cytosine
forms three hydrogen bonds with
Guanine
 The
hydrogen bonds keep the two strands
of DNA together
DNA Structure
 Strictness
of base pairing rules results in
two strands that form complementary base
pairs
 The
sequence on one strand determines the
sequence on the other strand
DNA Structure Worksheet
Ticket Out
 Finish
 DNA
each of these sentences:
looks like _____.
 I've heard of DNA in _______.
 The function of DNA is _______.
 DNA is used in society for _______.
 DNA is made of ________.
 I don't think DNA analysis should be used for
_______.