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Chapter 12
Name _________________
DNA
Information and Heredity, the cellular basis of life
12-1: DNA
Identifying the Substance of Genes
Frederick Griffith’s Experiments (1920s)
Bacterial Transformation
1. He was studying bacteria that cause ________________.
2. His experiment led to a discovery of a process a called ________________________:
- Process in which one strain of bacteria ____________ into another strain.
Bacterial Viruses - The _____________ cause of ______________.
What role did Bacterial __________ play in identifying the _________ material?
Oswald Avery (1940s)
1. His goal was to determine what ___________was used during _______________.
2. By a process of elimination using biological ____________, they discovered that
____ ____ _____
was the _________________ factor.
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The Hershey – Chase Experiment (Alfred Hershey & Martha Chase 1950s)
1. They did an experiment involving _________to prove the work of both
___________ & Avery.
2. Viruses are only made of two things:
- __________________
- __________________
3. In step 1 of their experiment, they tagged ______ ______with radioactive _______to
see if that was the ____________ factor. It was the transforming factor!!
4. In step 2 of their experiment, they tagged the _______ ______ with radioactive _____
to see if that was the _____________ factor.
The Role of DNA
It was not.
What is the role of DNA in ____________?
The DNA that makes up genes can:
1. ________information in the ____________
2. _______ this information in the cells.
3. _________ this information in the cells.
Study the book – cell analogy on page 342 of your textbook.A book can __________information, you can
_______information from this book and the book after being copied can be ____________ or
___________ to others.
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12-2: The Structure and components of DNA
1. A _____________ is the ___________ of a nucleic acid such as _____or RNA.
2. It has 3 components:
A _________________ group.
A 5 carbon sugar called _________________
A __________________ base
The DNA Nucleotide:
3. There are four different bases in DNA:
- ________________ (A)
- _________________ (T)
- ________________ (G)
4. These bases are placed in two groups:
- _________________ (C)
- ________________________ (double ring)  A & G
- ________________________ (single ring)  C & T
5. Chargaff’s Rules of Base Pairing:
- _______ pairs with ______
- _____ pairs with _____
- a _______________ will pair with a __________________
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The Double___________:
1. The structure of DNA was discovered through the work of three people:
A. _________________________ (1950s)
- she used a technique called
______________________________
to show that DNA has two strands that form a ________.
B.
James ____________ & Francis _____________ (1953)
- They expanded on Franklin’s work by building a ________of DNA.
- Their model had a __________ _________ structure
- The helix had a _________-___________ backbone.
- The __________ were in the _________ and held together by ________
_______.
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Section 12-3:Replication
What is replication?
__________________________________________________________________
__________________________________________________________________
The steps:
1. __________________________________ “unzips” the double helix by breaking the
___ bonds between the bases.
- Two helicase enzymes work in opposite directions & form a ________________
- The site where the helicase is doing the unzipping is called a _______________
The steps:
2. Within the replication bubble, two ___________________________________ work
in opposite directions & make a complementary strand of DNA.
3. At the end of replication, there are two ________ ________ of DNA.
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How does ___ ___ ___ replication differ in:
Prokaryotic cells
&
Eukaryotic cells?
-Prokaytoes or __________ cells normally have a _________ circular
strand of ___ ___ ___. Replication starts from a single point and proceeds
in 2 directions.
-In Eukaryotes or cells with a _____________, replication begins at
dozens or even ___________ of places and proceeds in both directions.
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