Warm-Up (12/03) Answer the following questions, and explain in a complete sentence why each answer is correct. Name Date Period What are the main functions of DNA polymerase?   A. breaks hydrogen bonds and exposes bases B. holds DNA strands apart and adds new bases C. zips and unzips the double-stranded DNA D. binds nucleotides and corrects base pair errors     D A Draw the structure to the right and label A, B, C and D. C B

DNA History Watson and Crick: found the structure of DNA Edwin Chargaff: found that A complements T and G complements C.

Guided Practice Chargaff found that some DNA was 10% adenine (A). What percentage was thymine (T)? What percentage was guanine (G) and cytosine (C)?

Your Turn – on your closure! Fleengaff found that some DNA was 35% adenine (A). What percentage was thymine (T)? What percentage was guanine (G) and cytosine (C)?

Cell Cycle Purpose #1 – to grow 10,000

Cell Cycle Purpose #2 – to replace dead cells What’s this cell going to do?

Cell Cycle 4 Steps: G1: normal life S: replicate DNA G2: grow M: divide Draw this!

Cell Cycle Draw this! The length of each phase depends on how badly it wants to divide!

Cell Cycle 3 Checkpoints G1: ready to copy DNA? G2: Replicated DNA all okay? M: Ready to divide?

Your Objective On the plate, Show the four stages of the cell cycle and state the function. Show the three checkpoints and state the function. State the two enzymes that work in S phase (yesterday).

Closure Answer the following question in a complete sentence: Name Date Period Do you think a skin cell would have a long or short G1 stage and why? Scale from 1-10