CHAPTER 10
DNA, RNA, AND PROTEIN
SYNTHESIS
Section 1 Discovery of DNA

All living
things have
DNA. Your
DNA holds
the
instructions
for
everything
about you.
FREDRICK GRIFFITH
 Discovered
transformation
the transfer of
genetic material from
one cell to another
cell or from one
organism to another
organism
He was looking for a vaccine against pneumonia.
Virulent- disease-causing
GRIFFITH’S EXPERIMENT
R (rough)
strain- no
capsule
 (harmless)
 S(smooth)
strain- has
a capsule
 (causes
pneumonia)

The capsule was destroyed with heat.
OSWALD AVERY
For years, people
thought that
genetic
information was
contained in cell
protein.
 Avery set out to
find out if the
transforming agent
in Griffith’s
experiment was
DNA, RNA, or
protein.

DNA, RNA, OR PROTEIN??
Avery and other scientists sequentially destroyed
DNA, RNA, and protein.
 In the RNA and protein- destroyed samples, the
mice died
 When DNA was destroyed, the mice lived.


His conclusion, DNA is the transforming agent in
bacteria.
HERSHEY-CHASE EXPERIMENT

Martha Chase and Alfred Hershey
BACTERIOPHAGE- A VIRUS THAT INFECTS
BACTERIA
HERSHEY-CHASE EXPERIMENT

Set out to answer the
question of whether
DNA or protein was
the hereditary material
viruses transfer when
they enter a bacteria
cell.
THEIR CONCLUSION:

DNA is the
hereditary
molecule in
viruses.
E. coli
SECTION 2: DNA STRUCTURE

By the early 1950s biologists accepted DNA as
the hereditary material, but did not understand
its structure or how the molecule could replicate,
store and transmit information, or direct cell
function.
JAMES WATSON AND FRANCIS CRICK

Credited with the discovery of the structure of DNA.
Perhaps even more significantly it explained how DNA
could replicate.

Received the
Noel Prize for
their work.
ROSALIND FRANKLIN

She took x-ray photographs of DNA that helped
DNA NUCLEOTIDES CONSIST OF 3 PARTS:
1) A five-carbon sugar
(deoxyribose)
2) A phosphate
3) a nitrogen base
(A) adenine
(T) thymine
(G) guanine
(C) cytosine
A DNA MOLECULE

Hydrogen
bonds are
located
between
the bases
TWO GROUPS OF BASES:

Purines- have
2 rings
Pyrimidines- have
one ring
BASE-PAIRING RULES:
Cytosine pairs with
Guanine
 Adenine pairs up
with Thymine

A plant’s DNA has nucleotides that are 20%
thymine. What percentage of guanine would be
present?
30%
COMPLEMENTARY BASE PAIRS

One purine pairs up with one pyrimidine
Just one more thing…
Use the base-pairing rules to determine the base sequence
that is complementary to the sequence
C-G-A-T-T-C-G
G-C-T-A-A-G-C