honors biology
Ch. 10 Notes
DNA
10.2 Describe the structure of DNA.
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Double Helix
Ladder:
o uprights (backbone) are repeating phosphate and sugar
o rungs are complementary nitrogen bases (1 dbl ring / 1 sgl)
Bonds
o Strong covalent bonds hold uprights together, keeps sequence
correct
o Weak hydrogen bonds hold bases together, easily “unzipped” by
enzymes for copying.
Uprights are “antiparallel” to each other ( ) due to ribose being
asymmetrical.
Structure: Watson and Crick 1953 (R. Franklin, M. Wilkins)
10.3 Compare the structure of DNA to RNA.
DNA
RNA
DeoxySUGAR
Ribose
ribose
Single stranded
May fold on itself (tRNA)
SHAPE
Double helix
May join with protein
(rRNA+protein  ribosome))
Nucleus
Cytoplasm
LOCATION
nucleus
rRNA
t-RNA
m-RNA
BASES
A, T, C, G
A, U, C, G
10.3 Explain how Chargaff’s rules relate to the structure of DNA.
A=T, C=G
10.4 Explain how the structure of DNA facilitates its
replication.
Mrs. Loyd 
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“It has not escaped our notice that the specific pairing we have
postulated immediately suggests a possible copying
mechanism for the genetic material.”
Each strand can be revealed for copying by breaking the
hydrogen bonds holding the bases together. Complementary
bases are then added in and the resulting molecules are half
old and half new (semiconservative replication).
Semiconservative Replication
o The blue half of each molecule is old and the gray half is new.
o This occurs during the S phase of Interphase.
o The result of this replication is identical sister chromatids.
o The purpose of replication is to provide two copies to be distributed to two
new cells.
o E. coli copies its entire genome, 4.6 million b.p., in under one hour.
o Humans copy 6 billion b.p. in a few hours
Leading strand replicates continuously. 3’ to 5’.
Lagging strand replicates in fragments (antiparallel) 3’ to 5’
In “The Secret of Photo 51”, which takes place just after World War II (1945), it is
apparent that Rosalind Franklin didn’t receive her due credit for her contributions
because she was a woman. It was tough for women to receive their just acclaim
if men were also involved.
There is a saying related to this that reminds me of DNA synthesis; Ginger
Rogers danced everything Fred Astaire did, but she did it backwards and in high
heels. (“Swing Time” 1936) and (The Barkleys of Broadway” 1949)
Mrs. Loyd 
cloyd@waukee.k12.ia.us
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10.6 The DNA genotype is expressed as proteins, which provide the
molecular basis for phenotypic traits.
The Central Paradigm
DNA  RNA  Protein
10.7 Genetic information written in codons is translated into
amino acid sequences.
10.8 The genetic code is the Rosetta Stone of life.
Given a DNA sequence, first transcribe it into mRNA and then
translate the codons into amino acids.
DNA:
T A C T T C A A A A T C
 transcription
RNA:
 translation
http://www.dnai.org/lesson/go/25129/
A.A.:
Mrs. Loyd 
cloyd@waukee.k12.ia.us
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10.15 Diagram the overall process of transcription and translation.
Use activity 10.15 for animation.
Mrs. Loyd 
cloyd@waukee.k12.ia.us
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10.16 Describe the major types of mutations, causes of
mutations, and possible consequences.
Major Types:
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point mutation (base substitution)
o example: sickle cell anemia
o consequences:
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ss = probably die of sickle cell
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Ss = survive sickle cell & malaria:
“heterozygote advantage”
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SS = may die of malaria
frame-shift mutation
o addition or deletion
o all downstream amino acids will be wrong.
o Consequences:
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lethal
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disease/condition
Causes:
o toxic chemicals
o radiation
10.17 Compare the lytic and lysogenic reproductive cycles of a phage
(virus).
Mrs. Loyd 
cloyd@waukee.k12.ia.us
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10.22 Define the processes of transformation, transduction, and
conjugation. See table made for notes in Ch. 8
TRANSFORMATION
TRANSDUCTION
CONJUGATION
INTEGRATION
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