2A. Distinguish between DNA and RNA. DNA Replication (12.2) State Standards 2A. Distinguish between DNA and RNA. 2B. Explain the role of DNA in storing and transmitting cellular information.

Chapter 12 Molecular Genetics 12.2 Replication of DNA Overview DNA has the unique ability to make an exact copy of itself in a process called replication.

Semiconservative Replication Chapter 12 Molecular Genetics 12.2 Replication of DNA Semiconservative Replication Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA.

Chapter 12 Molecular Genetics 12.2 Replication of DNA 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.

Step 1: Unwinding Cont’d Chapter 12 Molecular Genetics 12.2 Replication of DNA 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.

Chapter 12 Molecular Genetics 12.2 Replication of DNA Step 2: Base pairing DNA polymerase then adds complementary nucleotides to the chain. This continues until the entire molecule has been replicated.

Step 2: Base Pairing Cont’d Chapter 12 Molecular Genetics 12.2 Replication of DNA Step 2: Base Pairing Cont’d 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).

DNA ligase links the two sections. Chapter 12 Molecular Genetics 12.2 Replication of DNA 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.

Chapter 12 Molecular Genetics 12.2 Replication of DNA 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.

Eukaryotic vs. Prokaryotic DNA Eukaryotic DNA… Chapter 12 Molecular Genetics 12.2 Replication of DNA Eukaryotic vs. Prokaryotic DNA Eukaryotic DNA… - is found in the nucleus, coiled into chromosomes. - unwinds in multiple areas as DNA is replicated.

Eukaryotic vs. Prokaryotic DNA Cont’d Chapter 12 Molecular Genetics 12.2 Replication of DNA 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 .

Name the small segments of the lagging DNA strand. Chapter 12 Molecular Genetics Chapter Diagnostic Questions Name the small segments of the lagging DNA strand. ligase Okazaki fragments polymerase helicase A B C D CDQ 2

Which is not an enzyme involved in DNA replication? Chapter 12 Molecular Genetics 12.2 Formative Questions Which is not an enzyme involved in DNA replication? DNA ligase DNA polymerase hilicase RNA primer A B C D FQ 5

Standardized Test Practice Chapter 12 Molecular Genetics Standardized Test Practice What does this diagram show about the replication of DNA in eukaryotic cells? DNA is replicated only at certain places along the chromosome. DNA replication is both semicontinuous and conservative. Multiple areas of replication occur along the chromosome at the same time. The leading DNA strand is synthesized discontinuously. A B C D STP 1