Slide 1 of 21 Copyright Pearson Prentice Hall 12-2 Chromosomes and DNA Replication 12–2 Chromosomes and DNA Replication

12–2 Chromosomes and DNA Replication Slide 2 of 21 Copyright Pearson Prentice Hall DNA and Chromosomes In prokaryotic cells, DNA is located in the cytoplasm. Most prokaryotes have a single DNA molecule containing nearly all of the cell’s genetic information.

12–2 Chromosomes and DNA Replication Slide 3 of 21 Copyright Pearson Prentice Hall DNA and Chromosomes Chromosome E. Coli Bacterium Bases on the Chromosomes

12–2 Chromosomes and DNA Replication Slide 4 of 21 Copyright Pearson Prentice Hall DNA and Chromosomes Eukaryotes:  1000 times the amount of DNA as prokaryotes.  DNA is located in the cell nucleus inside chromosomes.  number of chromosomes varies widely from one species to the next.

Slide 5 of 21 Copyright Pearson Prentice Hall E-coli- 4.6 million base pairs Humans – 6 billion BP

12–2 Chromosomes and DNA Replication Slide 6 of 21 Copyright Pearson Prentice Hall DNA and Chromosomes Eukaryotic Chromosome Structure Chromosome Supercoils Nucleosome DNA double helix Histones Coils

12–2 Chromosomes and DNA Replication Slide 7 of 21 Copyright Pearson Prentice Hall DNA Replication Duplicating DNA Before a cell divides, it duplicates its DNA in a process called replication.

12–2 Chromosomes and DNA Replication Slide 8 of 21 Sugar (deoxyribose) Thymine (T) Nitrogenous base (A, G, C, or T) Phosphate group

12–2 Chromosomes and DNA Replication Slide 9 of 21 Copyright Pearson Prentice Hall DNA Replication In eukaryotic chromosomes  DNA replication occurs at hundreds of places

12–2 Chromosomes and DNA Replication Slide 10 of 21 Sugar (ribose) Uracil (U) Nitrogenous base (A, G, C, or U) Phosphate group

12–2 Chromosomes and DNA Replication Slide 11 of 21 3 end 5 end 3 end 5 end  P P P P P P P P

12–2 Chromosomes and DNA Replication Slide 12 of 21 The sites where separation and replication occur are called replication forks. Copyright Pearson Prentice Hall

12–2 Chromosomes and DNA Replication Slide 13 of 21 Parental DNA 3 5 DNA polymerase molecule DNA ligase 3 5 Overall direction of replication Daughter strand synthesized continuously Daughter strand synthesized in pieces

12–2 Chromosomes and DNA Replication Slide 14 of 21 Copyright Pearson Prentice Hall DNA Replication DNA molecule separates into two strands two new complementary strands following the rules of base pairing Each strand of the double helix of DNA serves as a template for the new strand – semiconservative model

12–2 Chromosomes and DNA Replication Slide 15 of 21 Copyright Pearson Prentice Hall DNA Replication Nitrogen Bases Replication Fork DNA Polymerase Replication Fork Original strand New Strand Growth

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