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WARM-UP #7
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DNA
(Deoxyribonucleic Acid)
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Genetic material of cells
GENES units of genetic material thatCODES FOR A SPECIFIC TRAIT
Called NUCLEIC ACIDS
DNA is made up of repeating moleculescalled NUCLEOTIDES
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DNA Nucleotide
O
O=P-OO
PhosphateGroup
N
Nitrogenous base(A, G, C, or T)
CH2
O
C1C4
C3 C2
5
Sugar(deoxyribose)
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A HISTORY OF DNA
Discovery of the DNA double helixA. ___________ Discovers that afactor in diseased bacteria can transformharmless bacteria into deadly bacteria
(1928)B. Avery, et al- Determine thetransforming factor is__________
(1944)
C. Hershey & Chase- tagged_________ & __________ of virusescalled ___________ and determined thatDNA controls _______________.
(1952)
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A HISTORY OF DNA
Discovery of the DNA double helix
D. ___________ Discovers that a factor indiseased bacteria can transform harmlessbacteria into deadly bacteria (1928)
E. _________________- X-ray photo ofDNA.
(1952)
F. _______________- described theDNA molecule from Franklins X-ray.
(1953)
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Chargaffs Rule
Number of Adenine =Thymine
Number of Guanine must pair with Cytosine
Their amounts in a given DNA molecule will beabout the same.
G CT A
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Watson & Crick proposed
DNA had specific pairing between thenitrogen bases:
ADENINETHYMINE
CYTOSINE - GUANINE
DNA was made of 2 long stands of
nucleotides arranged in a specificway called the Complementary Rule
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DNA Double Helix
NitrogenousBase (A,T,G or C)
Rungs of ladder
Legs of ladder
Phosphate &Sugar Backbone
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DNA Double Helix
P
P
P
O
O
O
1
23
4
5
5
3
3
5
P
P
P
O
O
O
1
2 3
4
5
5
3
5
3
G C
T A
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Nitrogenous Bases
PURINES
1. Adenine (A)
2. Guanine (G)
PYRIMIDINES
3. Thymine (T)
4. Cytosine (C) T or C
A or G
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BASE-PAIRINGS
CG
H-bonds
T A
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Genetic Diversity
Differentarrangements ofNUCLEOTIDES in anucleic acid (DNA)
provides the key toDIVERSITY amongliving organisms.
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The Code of Life
The code of the chromosome is the
SPECIFIC ORDER that bases occur.
A T C G T A T G C G G
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DNA is wrapped tightly around
________and coiled tightly to
form chromosomes
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DNA Replication DNA must be copied
The DNA molecule produces 2IDENTICAL new complementarystrands following the rules ofbase pairing:
A-T, G-C
Each strand of theoriginal DNA serves asa template for the newstrand
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DNA Replication
SemiconservativeModel:
1. Watson and Crick
showed: the two strandsof the parental moleculeseparate, and eachfunctions as a templatefor synthesis of a newcomplementary strand.
. Parental DNADNA Template
New DNA
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1. Why is replication necessary?
2. When does replication occur?
3. Describe how replication works.
4. Use the complementary rule tocreate the complementary
strand:
A---?
G---?C---?T---?A---?
G---?A---?G---?C---?A---?G---?T---?
Replication Quiz
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AMAZING DNA FACTS
DNA from a single humancell extends in a singlethread for almost 2 meters
long!!!
It contains informationequal to some 600,000printed pages of 500 wordseach!!!
(a library of about 1,000 books)
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LETS REVIEW DNA
1. List the conclusions Griffith & Avery,Hershey & Chase drew from their
experiments.2. Summarize the relationship between
genes & DNA.
3. Describe the overall structure of theDNA molecule.
4. What are the 4 kinds of bases?