copyright cmassengale 4/4 Agenda: Warm Up DNA Replication Notes (TOC#__) Edible DNA Replication Activity Homework: Complete Lab Questions Complete study guide for the quiz on friday Purpose: Explore DNA replication, what it is, where it occurs and how it takes place. copyright cmassengale

copyright cmassengale Warm Up 4/4 If there is 30% Adenine in a DNA molecule, how much Cytosine is present? How do you think new DNA could be made? copyright cmassengale

copyright cmassengale Answer: There would be 20% Cytosine Adenine (30%) = Thymine (30%) Guanine (20%) = Cytosine (20%) Therefore: 60% A-T and 40% C-G copyright cmassengale

copyright cmassengale DNA Replication What Why Where How Steps of Replication copyright cmassengale

copyright cmassengale DNA Replication WHAT What: Making a copy of the DNA copyright cmassengale

copyright cmassengale DNA Replication - WHAT Model: Semiconservative Model of Replication Idea presented by Watson & Crick The two strands of the parental molecule separate, and each acts as a template for a new complementary strand New DNA consists of 1 PARENTAL (original) and 1 NEW strand of DNA Parental DNA DNA Template New DNA copyright cmassengale

copyright cmassengale DNA Replication WHY 2. Why: Because we need to make more DNA for new cells DNA has to be copied before a cell divides New cells will need identical DNA strands copyright cmassengale

copyright cmassengale DNA Replication WHERE 3. Where: Nucleus of eukaryotes Because that is where the DNA is copyright cmassengale

copyright cmassengale DNA Replication HOW 4. How: Begins at Origins of Replication Two strands open forming Replication Forks (Y-shaped region) New strands grow at the forks Replication Fork Parental DNA Molecule 3’ 5’ copyright cmassengale

copyright cmassengale DNA Replication HOW As the 2 DNA strands open at the origin, Replication Bubbles form Prokaryotes (bacteria) have a single bubble Eukaryotic chromosomes have MANY bubbles Bubbles Bubbles copyright cmassengale

DNA Replication - Process Large team of enzymes coordinates replication Enzymes more than a dozen enzymes & other proteins participate in DNA replication

How: Replication: 1st step Unwind DNA helicase enzyme unwinds part of DNA helix by breaking the weak hydrogen bonds between the nitrogenous bases single-stranded binding proteins replication fork helicase

HOW: Replication: 2nd step Build daughter DNA strand DNA polymerase III: adds new complementary bases DNA Polymerase III

3rd step: Proofreading New DNA DNA polymerase initially makes about 1 in 10,000 base pairing errors Enzymes proofread and correct these mistakes The new error rate for DNA that has been proofread is 1 in 1 billion base pairing errors What do you notice about enzyme names? copyright cmassengale

Activity: Edible DNA and Replication Objectives: Students will learn and demonstrate the structure and function of DNA, an essential component of any cell. Materials: copyright cmassengale

Activity: Edible DNA and Replication Part I: Building a DNA Model 1. Use a diagram of DNA (you could use the DNA Coloring sheet!) and the key below to build four different nucleotides

Groups of 4 2 Construction workers 1 reader 1 supply manager Build the models 1 reader Read the lab together (read all the questions too) 1 supply manager Get all the supplies for the group 4 note takers/Cleaners You are each responsible for turning in a lab and making sure your station is clean