Download Bio Ch. 12-1 DNA and RNA notes

DNA and RNA
Biology
Ch. 12
The Structure of DNA
• Nucleotides are the
monomeric units that
make up DNA
 3 main parts:
 5 carbon sugar—
deoxyribose
 Phosphate group
 Nitrogenous base
The Structure of DNA
• There are four kinds
of bases in in DNA:
•
•
•
•
adenine
guanine
cytosine
thymine
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The Structure of DNA
• The backbone of a
DNA chain is formed
by sugar and
phosphate groups of
each nucleotide.
• The nucleotides can
be joined together in
any order.
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The Structure of DNA
• Chargaff's Rules
– Erwin Chargaff discovered that:
• The percentages of guanine [G] and cytosine [C]
bases are almost equal in any sample of DNA.
• The percentages of adenine [A] and thymine [T]
bases are almost equal in any sample of DNA.
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• X-Ray Evidence
– Rosalind Franklin
used X-ray
diffraction to get
information about
the structure of
DNA.
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http://www.chem-is-try.org/wpcontent/uploads/2009/03/rosalind-franklin.jpg
The Structure of DNA
The Structure of DNA
• Using clues from
Franklin’s pattern,
James Watson and
Francis Crick built a
model that explained
how DNA carried
information and could
be copied.
http://history.nih.gov/exhibits/nirenberg/images/photos/03_watCrk_pu.jpg
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The Structure of DNA
• Watson and Crick's
model of DNA was a
double helix, in which
two strands were
wound around each
other.
http://gregortimlin.files.wordpress.com/2009/05/watsonjames-crickfrancis.jpg
The Structure of DNA
Double Helix
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The Structure of DNA
• Watson and Crick
discovered that
hydrogen bonds can
form only between
certain base pairs—
adenine and thymine,
and guanine and
cytosine.
• This principle is called
base pairing.
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DNA Structure
Avery and other scientists discovered that
a) DNA is found in a protein coat.
b) DNA stores and transmits genetic information
from one generation to the next.
c) transformation does not affect bacteria.
d) proteins transmit genetic information from one
generation to the next.
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The Hershey-Chase experiment was based on
the fact that
a) DNA has both sulfur and phosphorus in its
structure.
b) protein has both sulfur and phosphorus in its
structure.
c) both DNA and protein have no phosphorus or
sulfur in their structure.
d) DNA has phosphorus, while protein has sulfur in
its structure.
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DNA is a long molecule made of monomers
called
a)
b)
c)
d)
nucleotides.
purines.
pyrimidines.
sugars.
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Chargaff's rules state that the number of
guanine nucleotides must equal the number of
•
•
•
•
cytosine nucleotides.
adenine nucleotides.
thymine nucleotides.
thymine plus adenine nucleotides.
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In DNA, the following base pairs occur:
a)
b)
c)
d)
A with C, and G with T.
A with T, and C with G.
A with G, and C with T.
A with T, and C with T.
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