Monday 11/9/15 LEARNING GOAL: Accurately pair nitrogen bases in a DNA molecule and demonstrate how a molecule of DNA is replicated. WARM UP: What are the four nitrogen bases in a DNA molecule? How are they paired? HOMEWORK: Finish DNA Strand Activity if needed. Study for your Test on Chapter 3 Sections 3, 4, & 5 on Wednesday!

Warm up: What are the four nitrogen bases in a DNA molecule? How are they paired?  Adenine (A)  Thymine (T)  Guanine (G)  Cytosine (C)

The Structure of DNA

Looks like a twisted ladder, or spiral staircase The sides of the ladder are made up of  Deoxyribose (sugar)  Phosphate Each rung of the ladder is made up of a pair of molecules called nitrogen bases  Adenine (A)  Thymine (T)  Guanine (G)  Cytosine (C)

The Replication Process The two sides of the DNA molecule unzip and separate Nitrogen bases floating in nucleus pair up with the bases on each half of the DNA molecule New bases attach, two new DNA molecules form

GATHER YOUR SUPPLIES 1 bag of marshmallows  Each bag should have:  4 pink  4 orange  4 yellow  4 green 8 toothpicks 2 Twizzlers

Building a DNA molecule Marshmallows: Pink = Adenine (A) Yellow = Thymine (T) Green = Guanine (G) Orange = Cytosine (C)

Practice #1 This is your original strand C G T G G A A Create your copied strand

Practice #2 This is your original strand A A C C T C G T Create your copied strand

Practice #3 This is your original strand A G C T T A C G Create your copied strand

DNA Replication Working with a partner: 1. Build one full DNA strand 2. Start to “unzip” the DNA strand one base pair at a time 3. Model replication by building two new DNA molecules from the original strand by pairing one base set at a time