1. HSPE Testing Day Tuesday, March 13 1)Short check up Friday - on DNA Structure and Replication 2)Word Wall due on Friday

2. Answer these questions in yesterday’s entry: 1) Where in the cell is DNA located? 2) The backbone (sides of the ladder)in a DNA molecule are made of….? 3)Draw and Label  4) What type of bond holds the bases together? 5) What are the 4 bases in DNA and what are the base-pairing rules?

3. 1)Where in the cell is DNA located? -Plant/Animal Cells (eukaryotic cells)= nucleus -Bacteria (prokaryotic cells)= no nucleus, DNA in cytoplasm 2) The backbone (sides of the ladder)in a DNA molecule are made of….? Sugar and phosphate

4. 3)Draw and Label  4) What type of bond holds the bases together? Hydrogen Bonds 5) What are the 4 bases in DNA and what are the base-pairing rules? Adenine, Thymine, Guanine, Cytosine Base-Pairing Rules: A  T, G  C Phosphate Sugar Base

5. Make an entry: Entry 22: DNA REPLICATION-3/13/12

6. DNA Replication Whenever a cell divides into two new cells, it needs to make an exact copy of the DNA. The process of copying DNA is called DNA replication.

7. Why do you need more DNA? you need to make more DNA- in order to make more cells…. skin cells, heal injury, grow

8. Enzymes in DNA replication Enzymes are proteins that act as machines in the cell 2 enzymes do the work of DNA replication: –Helicase is responsible for separating the 2 strands of DNA –DNA Polymerase is responsible for adding on new Nucleotides.

10. Original DNA Helicase unzips DNA DNA polymerase creates a complementary strand

11. Show Animation files:

13. DNA Replication Steps: 1)helicase (enzyme) causes nucleotide chains to separate which breaks the hydrogen bonds

14. DNA Polymerase A Phosphate- Sugar bond T 2) DNA polymerase bonds to each chain and begins adding free nucleotides found in the nucleus Makes bonds between Phosphate and sugar on the nucleotides.

15. Complementary base pairing If one strand of DNA has the following sequence, CTAATGT What is the base sequence (order of nucleotides) for the complimentary strand? GATTACA

16. When replication is completed: –2 new strands are identical to the original –Each new strand has ½ new nucleotide chain and ½ original nucleotide chain

17. Complicated picture of replication…

18. Replication in Action Replication occurs simultaneously at multiple places along a DNA strand. –1 chromosome is about 80 million base pairs long. –Replication is as fast as 50 base pairs a second! Nobel e-Museum: DNA

20. You do not need to make an entry for either: Word Wall due Friday Review Sheet is what you need to know for Friday