DNA: DNA Replication 11/18/15
DNA REPLICATION • Question 1 • How do organisms grow? • Question 2 • What has to happen before a cell can divide? • Question 3 • What will happen to the cells if DNA replication does not occur? I X I I
DNA REPLICATION • DNA replication: the process of making a copy of one strand of DNA • DNA replication has to occur before a cell can divide DNA Replication DNA Cell Division
2. Four Nitrogen Bases found in DNA • Adenine- A Thymine- T • Guanine- G Cytosine-C 3. Nitrogen bases pair up to keep the two strands of the DNA molecule bonded together.
6.Process of DNA Replication • A. Replication begins when the two strands of the DNA moleculeseparate. • B. Free nucleotides found floating around in the nucleus attach to the exposed nitrogen bases according to the base pairing rules. Watch Video on DNA Replication
Process of DNA Replication • C. As a result a complementary strand forms next to each original strand of DNA and two identical DNA molecules form. • 8. Complementary- the manner in which the nitrogenous bases of the DNA molecule align (pair) with each other.
9. Enzymesare present during replication that assist with each step of the process.
DNA REPLICATION (write on the top of page) • Replication • Enzyme DNA Helicase breaks the hydrogen bonds between the bases • Nitrogen bases are exposed HELICASE
DNA REPLICATION • Replication (cont.) • DNA Polymerase adds free nucleotides to the single stranded DNA • DNA polymerase Proofreads the bases DNA Polymerase Nucleotides
Direction of replication Direction of replication Helicase Helicase Replication Forks DNA REPLICATION • 3,000 nucleotides/min • 3.2 billion nucleotides in the human genome • 1,066,666 minutes to copy the human genome (2 years) • Multiple replication forks speed up replication
DNA REPLICATION • DNA replication is semiconservative • Result is two new DNA strands (daughter strands). Each is composed of 1/2 original strand and 1/2 new DNA
On your own: • Where does DNA replication occur in a eukaryotic cell? • What are the base-pairing rules for DNA? • What would be the complementary strand for the DNA strand A-T-T-C-G-G-A-T-C? • How do the two new DNA molecules that result from DNA replication compare with each other? • How does each new DNA molecule that results from DNA replication compare with the original DNA molecule? • How are the nucleotides arranged in a DNA molecule?
On your own: • Where does DNA replication occur in a eukaryotic cell? • Nucleus • What are the base-pairing rules for DNA? • A-T, G-C • What would be the complementary strand for the DNA strand A-T-T-C-G-G-A-T-C? • T-A-A-G-C-C-T-A-G • How do the two new DNA molecules that result from DNA replication compare with each other? • Identical Copies • How does each new DNA molecule that results from DNA replication compare with the original DNA molecule? • Complementary • How are the nucleotides arranged in a DNA molecule? • Stacked on top of one another