Understanding DNA Replication: Structure and Process Explained
This chapter provides a concise overview of DNA replication, essential for cell division. DNA, a nucleic acid, comprises deoxyribose, phosphate, and nitrogen bases: guanine, cytosine, adenine, and thymine, forming a double helix structure. DNA replication occurs in three steps: unwinding by DNA helicase, complementary base pairing, and joining by DNA polymerase. The process is semi-conservative, yielding one old strand and one new strand in each double helix. This critical mechanism occurs in the nucleus before cell division and is fundamental for maintaining genetic continuity.
Understanding DNA Replication: Structure and Process Explained
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Presentation Transcript
Chapter 25 DNA replication
DNA Review • DNA is a nucleic acid • The components are • Deoxyribose • Phosphate • Nitrogen Base • The nitrogen bases are • Guanine, Cytosine, Adenine, and Thymine • The structure is... • Double helix
DNA Replication • DNA needs to be replicated so cells may divide • 3 steps in replication • Unwinding The two strands that were held together by hydrogen bonds separate and the hydrogen bonds break. The Enzyme DNA Helicase “unzips” the DNA • Complementary Base Pairing nucleotides fit into place • Joining the complementary nucleotides join together to make new strands. They are joined with the enzyme DNA Polymerase
This is the Unwinding stage. DNA Helicase This is where the Nitrogen Base Pairs pair up with the old DNA DNA Polymerase combines the nucleotides and changes it into a new strand
This DNA replication is called Semiconservative because each new double helix has one old strand and one new strand • DNA replication occurs in the nucleus and it needs to happen before cell division • The old strand is called the parent strand • The new strand is called the daughter strand
