Question of the Day: What did Watson and Crick discover, and what woman unknowingly helped them along the way? Objective: After completing the 12-2 notes I will understand how DNA is duplicated and be able to correctly color a strand of DNA during replication.

12-2 Chromosomes and DNA Replication Ag Biology CA Standards: 5. The genetic composition of cells can be altered by incorporation of exogenous DNA into the cells. As a basis for understanding this concept: b. Students know how to apply base-pairing rules to explain precise copying of DNA during semiconservative replication and transcription of information from DNA into mRNA.

12-2 Vocabulary Histone (B)Globular protein molecule around which DNA is tightly coiled in chromatin. (A)DNA is tightly wrapped around proteins called ___________ in order form __________ in the nucleus. Nucleosome Nucleosome is simply a word you will come across, it’s simply a bunch of histones together with DNA wrapped around them.

12-2 Vocabulary Chromatin (A) Granular material visible within the nucleus; consists of DNA tightly coiled around proteins. (B) In the cell’s __________, DNA is wound around _________ to create ___________ in order to store DNA efficiently. What is this protein called??

12-2 Vocabulary Replication (A)Copying process by which a cell duplicates its DNA. (B) DNA is _________ in a process called _______________.

12-2 Vocabulary DNA Polymerase (B)Enzyme that “proofreads” new DNA strands, helping to ensure that each molecule is a perfect copy of the original DNA. (A) In order to make sure that DNA is copied perfectly, an __________ called DNA ____________ is in charge of “_____________” new DNA strands.

12-2 Notes A. Duplicating DNA (A) In mitosis, what had to happen before Prophase?? (B) What type of bonds are broken to separate the DNA strand? 12-2 Notes A. Duplicating DNA 1. Replication: the process used for copying a cell’s DNA before the cell divides A DNA molecule separates into two strands, then produces two new complementary strands using base pairing DNA replication is semi- conservative because one original strand is used as a template to form a complementary strand and both become the new DNA double-helix So in mitosis, right?? Because cell divides into 2 cells. Replication is the whole strand!

12-2 Notes B. How Replication Occurs (A) How are the four bases paired together? B. How Replication Occurs 1. An enzyme, called DNA polymerase, carries out DNA replication and “proof-reads” new strands for errors They “unzip” a molecule of DNA, breaking the hydrogen bonds, and strands unwind, serving as a template for complementary bases to attach Two identical DNA molecules are produced

12-2 Review Please get out a piece of paper and copy down the questions and answers in order to turn in at the end of class (Name, date, and period in top right corner please). 1. (B) How is DNA replicated? The DNA molecule separates into two strands, which each serve as a template for new, complementary strands to be made, following the rules of base pairing. 2. (A) Where is eukaryotic DNA stored, and in what form is it? In the cell nucleus, in chromosomes (chromatin)

12-2 Review Continued 3. (B) How is DNA “packaged” in the cell nucleus? DNA molecule is wrapped around histone proteins, forming nucleosomes which then coil to form chromatin fibers and super coil to form chromosomes.

Coloring Time! 12-2 Review Continued 4. (A) What is the role of DNA Polymerase in DNA replication? It polymerizes individual nucleotides to produce DNA. In addition, it “proofreads” new strands to catch mistakes. Coloring Time! Put coloring assignment on the docucam At 10:16 have students write in learning log!