DNA Replication (12.2) State Standards 2A. Distinguish between DNA and RNA. 2B. Explain the role of DNA in storing and transmitting cellular information.
Jan 03, 2016
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DNA Replication (12.2)
State Standards
2A. Distinguish between DNA and RNA.
2B. Explain the role of DNA in storing and transmitting cellular information.
12.2 Replication of DNA
Molecular Genetics
Overview
Chapter 12
DNA has the unique ability to make an exact copy of itself in a processcalled replication.
12.2 Replication of DNA
Molecular Genetics
Semiconservative Replication Parental strands of
DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA andone strand of new DNA.
Chapter 12
Molecular Genetics
Step 1: Unwinding DNA helicase, an enzyme, breaks the hydrogen bonds holding the base pairs together. It unwinds and unzips the double helix, allowing new nucleotides to bind to the 2 single strands by base pairing.
12.2 Replication of DNA
Chapter 12
Molecular Genetics
Step 1: Unwinding Cont’d As the double helix is unwound & unzipped,
RNA primase adds a short segment of RNA, called an RNA primer (starter), on each DNA strand.
12.2 Replication of DNA
Chapter 12
Molecular Genetics
Step 2: Base pairing DNA polymerase then adds complementary
nucleotides to the chain. This continues until the entire molecule has been replicated.
12.2 Replication of DNA
Chapter 12
Molecular Genetics
One strand is called the leading strand & is built continuously.
The other strand is called the lagging strand & is built discontinuously in small fragments (Okazaki fragments).
12.2 Replication of DNA
Chapter 12
Step 2: Base Pairing Cont’d
Molecular Genetics
Step 3: Joining DNA polymerase removes the RNA primer
and fills in the place with DNA nucleotides. DNA ligase links the two sections. Each new strand is half original DNA &
half new DNA.
12.2 Replication of DNA
Chapter 12
Molecular Genetics
Conclusion There are now 2
copies of the genetic information that will be passed on to new cells through mitosis or to the next generation through meiosis.
12.2 Replication of DNA
Chapter 12
12.2 Replication of DNA
Molecular Genetics
Eukaryotic vs. Prokaryotic DNA Eukaryotic DNA…
- is found in the nucleus, coiled into chromosomes.
- unwinds in multiple areas as DNA is replicated.
Chapter 12
12.2 Replication of DNA
Molecular Genetics
Eukaryotic vs. Prokaryotic DNA Cont’d
. Prokaryotic DNA…
- is attached to the plasma membrane or is free-floating.
- is circular & only opens at one origin of replication.
• DNA is also found in chloroplasts & mitochondria
Chapter 12
1. A2. B3. C4. D
CDQ 2
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Molecular Genetics
Chapter Diagnostic Questions
Chapter 12
A. ligase
B. Okazaki fragments
C. polymerase
D. helicase
Name the small segments of the lagging DNA strand.
1. A2. B3. C4. D
FQ 5
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Molecular GeneticsChapter 12
12.2 Formative Questions
A. DNA ligase
B. DNA polymerase
C. hilicase
D. RNA primer
Which is not an enzyme involved in DNA replication?
1. A2. B3. C4. D
STP 1
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Molecular GeneticsChapter 12
What does this diagram show about the replication of DNA in eukaryotic cells?
Standardized Test Practice
A. DNA is replicated only at certain places along the chromosome.
B. DNA replication is both semicontinuous and conservative.
C. Multiple areas of replication occur along the chromosome at the same time.
D. The leading DNA strand is synthesized discontinuously.
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