8.2 Structure of DNA
DNA structure is the same in all organisms.
Question Set #1 Go to the link and answer the question in
your DNA Project Guide.
Glowing Mice
8.2 Structure of DNA
• Question Set #2
Go to the link below and watch the first 11:00 minutes of
“Cracking the Code of Life”. Answer the questions in DNA
Project Guide.
https://www.youtube.com/watch?v=_IgSDVD4QEc
8.2 Structure of DNA
DNA—(Deoxyribonucleic Acid)-a nucleic acid that
carries the genetic information of the cell.
It forms and controls the physical make-up and
chemical processes of living organisms.
IN OTHER WORDS—IT IS THE
“CODE OF LIFE”
8.2 Structure of DNA
DNA is composed of four types of nucleotides.
• DNA is made up of a long chain of nucleotides.
• Each nucleotide has three parts.
– a phosphate group
– a deoxyribose sugar
– a nitrogen-containing base
phosphate group
deoxyribose (sugar)
nitrogen-containing
base
8.2 Structure of DNA
• The nitrogen containing bases are the only difference in
the four nucleotides. Be sure to put all 4 bases in your
notes!!
8.2 Structure of DNA
• Question Set #3
• The History of DNA
• Go to the site “Interactives of DNA” using the link below.
Use the timeline to answer the questions in your DNA
Project Guide.
Interactives of DNA
8.2 Structure of DNA
Watson and Crick determined the three-dimensional
structure of DNA by building models.
• They realized that DNA is
a double helix that is
made up of a sugarphosphate backbone on
the outside with bases on
the inside. In 1953, they
won the Nobel Prize for
the discovery of the
double helix structure of
DNA.
8.2 Structure of DNA
• Watson and Crick’s discovery built on the work of Rosalind
Franklin and Erwin Chargaff.
– Franklin’s x-ray images suggested that DNA was a
double helix of even width.
8.2 Structure of DNA
Nucleotides always pair in the same way.
• The base-pairing rules show
how nucleotides always pair
up in DNA.
– A pairs with T
– C pairs with G
• Because a pyrimidine
(single ring) pairs with a
purine (double ring), the
helix has a uniform width.
G
C
A T
8.2 Structure of DNA
• The backbone is connected by covalent bonds.
• The bases are connected by hydrogen bonds.
hydrogen bond
covalent bond
8.2 Structure of DNA
Nucleic Acids
Store Information!
• Nitrogenous bases form a code with four
“letters”.
• Inside the cell, this code is deciphered and
used as a template to build proteins (you
will get the details on this later on).
• All cells in an organism have the same
molecules of DNA in every cell. In other
words, each cell carries the same “library”
of information in its nucleus.
8.2 Structure of DNA
DNA GAME
Question Set #4
Go to the link below. Play the DNA Double Helix Game.
Place the names of the three identified organisms on your
DNA Project Guide.
DNA The Double Helix Game
8.2 Structure of DNA
Nucleotide Polymers
•A strand of DNA can have more than 100 million nucleotides linked in a
chain. A train with that many cars would easily stretch across the US. And
I’m talking about a toy train with cars only a couple of inches long!
8.2 Structure of DNA
I:Anatomy of A Chromosome
• Click on the hyperlink and view
the interactive.
Journey into Human
DNA
8.2 Structure of DNA
Karyotypes—Human Chromosomes—Just for Fun!!