Download DNA!

DNA!
Part 1
The Scientists
Scientists
Research Qs
Conclusions
Griffith
What causes virulence in
bacteria?
The ability to cause
disease is heritable.
(Side note:
polysaccharides are
not responsible for
causing disease)
Avery
What organic compound
is the transforming factor
that allows harmless
bacteria to produce
harmful offspring?
DNA (by ruling out
proteins and lipids)
Hershey &
Chase
What is the molecule of
heredity?
DNA (has the
instructions to build
new viruses)
**Packet page 7**
Catalyst
(You can do this catalyst in space that you
find on page 8 of your packet)
You are studying a segment of DNA that is
200 base pairs long.
15% of the total monomers in this molecule
are guanine.
• How many nucleotides are there in total?
_____
• What percent of the nucleotides are
thymine? _____
• How many thymine nucleotides are there?
_____
• How do you know this?
Nucleic acids
**Packet page 8**
• DNA (deoxyribose nucleic acid) and RNA
(ribonucleic acid) are both nucleic acids
• The monomers of nucleic acids are
nucleotides
• All nucleotides have a nitrogenous base, a
sugar, and a phosphate group
• There are 4 DNA nucleotides, they are
named after their nitrogenous bases:
Guanine
DNA structure
• Double helix (two connected twists) with
uniform diameter.
• The shape was discovered by Watson
and Crick when they viewed an x-ray
produced image made by Rosalind
Franklin (without her permission).
DNA structure
• Watson and Francis Crick worked out
how the helix formed using pieces of
information from other scientists
– Franklin: the sides of the "ladder" are made of
connecting sugars and phosphate groups, the
nitrogenous bases are on the inside
– Erwin Chargaff: the amount of adenine is
always equal to the amount of thymine; and,
the amount of guanine is always equal to the
amount of cytosine ("Chargaff's Rules")
DNA structure:
base pairing
•Since purines are larger than pyrimidines, the
only way for a uniform thickness of DNA was to
have a purine always pair with a pyrimidine:
adenine pairs with thymine, guanine pairs with
cytosine