Bellwork: Mon: Nov 22,2010 2. Which bases are which? A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand. Write out the original and complimentary Strand: GCGAATTCG 2. Which bases are which? Draw them. How do you know: 3. What are these colored genes called? (hint: think of the video we watched “What Darwin Never Knew”)

Eukaryotic Chromosome Structure Nucleosome DNA double helix Coils Supercoils Eukaryotic chromosomes contain DNA wrapped around proteins called histones. The strands of nucleosomes are tightly coiled and supercoiled to form chromosomes. Histones

DNA Replication Replication: before a cell divides, it duplicates its DNA so each new cell will have a complete set of DNA. DNA molecule separates into two strands, then produces two new complementary strands

Copyright Pearson Prentice Hall DNA Replication New Strand Original strand Nitrogen Bases Growth Growth During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand. Replication Fork Replication Fork DNA Polymerase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall DNA Replication How Replication Occurs DNA replication is carried out by enzymes that “unzip” a molecule of DNA. Hydrogen bonds between base pairs are broken and the two strands of DNA unwind. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 12–2 The structure that may play a role in regulating how genes are “read” to make a protein is the coil. histone. nucleosome. chromatin. Copyright Pearson Prentice Hall