Connect!
•What is the
hereditary
molecule?
•Brainstorm
everything you
know about DNA.
MODERN GENETICS
• DNA is the hereditary material.
Cells of living organisms use a
chemical code to transfer information
from one generation to another. The
chemical code is DNA.
DNA Facts
1. DNA is a nucleic acid
which is an organic
compound. Biochemists
have found that DNA
(deoxyribonucleic acid)
is the genetic material
which replicates and is
passed from generation
to generation.
Chunk!
• What is the hereditary material?
• What do the letters DNA stand for?
• How is genetic material passed from
one generation to the next?
2. DNA is
found in
the
nucleus of
cells and
controls
the cell by
influencing
the
production
of
proteins.
3. DNA Structure
• is a polymer
which means it
has many
repeating units
•
consists of
thousands of
smaller
repeating units
known as
nucleotides
• a DNA nucleotide has 3 parts:
 a phosphate group
 a sugar (deoxyribose) molecule
 a nitrogenous base.
• There are 4 possible bases:
Chunk!
•
•
•
•
Where is DNA found in the cell?
How does DNA control a cell?
Why is DNA considered a polymer?
What are the repeating units that make
up DNA called?
• Name the 3 parts of a nucleotide.
• What does the “house” represent?
…the “pool”? …the “garage”?
• Name the 4 bases.
4. The scientists Watson and Crick
developed a model of the DNA
molecule.
Their model consists of the following:
• The DNA has 2
complementary chains.
• The DNA molecule has
a ladder type
organization with the
uprights composed of
the phosphate and
deoxyribose molecules.
The rungs of the ladder
are composed of bases
held together by weak
hydrogen bonds.
• The bases only pair with specific bases:
adenine (A) – thymine (T)
guanine (G) – cytosine (C)
• The shape of each base is
represented by a different form, as
above.
• Why do A and T base pair?
• Why do C and G base pair?
• The DNA ladder is thought to be
twisted in the form of a double helix.
Chunk!
• Who discovered the structure of DNA?
• What does it mean when it is said the DNA
consists of “2 complementary chains”?
• What makes up the “rungs” of the
“ladder”?
• What makes up the “uprights” of the
“ladder”?
• What holds the bases together?
• What shape is the DNA molecule?
• Fill in the
missing bases in
the DNA
diagram at
right.
DNA Functions
•
DNA has 2 functions which are
1. Replication of the genetic code for
reproduction
2. Control of the activities of the cell by
the synthesis of proteins, specifically
enzymes
Chunk!
• What are the two functions of DNA?