2.  Who was Gregor Mendel and what did he discover?  How many chromosomes are found in the nucleus of each human body cell?  During cell division, your cells DNA is replicated during which part of the cell cycle?  G 1 (Growth Phase  S (synthesis) G2G2

3.  After Mendel’s work, scientists wondered what are genes made of?  Through experimentation of scientists **Griffith, Hershey, & Chase**, scientists became convinced that genes were made of DNA  One question then arose….  What is the structure of DNA?

4.  I can – describe the structure of DNA

5.  DNA Structure  Knowing the structure of DNA was important because it clarified how DNA could serve as genetic material  Scientists **Watson & Crick** pieced together a model of the structure of DNA

6.  DNA Structure  Double helix- 2 strands twisted around each other (winding staircase)  Each strand was made of nucleotides. (subunits of DNA)

7.  Each nucleotide is made of 3 parts. ◦ A phosphate group ◦ A five carbon sugar - deoxyribose ◦ A nitrogen containing base  Adenine (A) Guanine (G)  Thymine (T) Cytosine (C) ◦ Draw & label the three parts of a nucleotide in the box your notes

8. DNA resembles a ladder twisted like a spiral staircase. The bases represent the ladder’s rungs The bases are bonded together by weak hydrogen bonds The sugar and phosphate group are the “backbone” for DNA

9. Adenine & Guanine are considered “Purines” Cytosine & Thymine are “Pyrimidines”

10.  The double helix is held together by weak hydrogen bonds between the pair of bases.  Base pairing rules- Adenine pairs with Thymine (A-T) Cytosine pairs with Guanine (C-G)  The sequence of bases on one strand determines the sequence of bases on the other strand.

13.  If the sequence on one strand of DNA can determine sequence of other strand then….  One strand of DNA contains nitrogen bases in this order.. AA TT GG AA CC CC What will the complementary DNA strand look like?

14.  If the sequence on one strand of DNA can determine sequence of other strand then….  The second strand will look like this.. ATAT TATA GCGC ATAT CGCG CGCG What type of bonds hold these strands of bases (the ladder’s rungs) together?

15.  If the sequence on one strand of DNA can determine sequence of other strand then….  The second strand will look like this.. TT GG CC GG AA TT What will the complementary strand look like?

16.  If the sequence on one strand of DNA can determine sequence of other strand then….  The second strand will look like this.. TATA GCGC CGCG GCGC ATAT TATA

17.  Create one strand of DNA with 8 nitrogen bases. Have your partner complete the complementary strand TATA GCGC CGCG GCGC ATAT TATA

18.  Describe the 3 parts of a DNA nucleotide  Name the bonds that hold together the nitrogen bases in a DNA strand  List the abbreviations for the four nitrogen bases of DNA

19.  I can – explain the three steps in DNA replication  I can – create two replicated strands of DNA

20.  Replication of DNA  **Remember – DNA is replicated during the “S” (synthesis)phase in cell division  DNA Replication: making a copy of DNA

21.  Replication of DNA  In DNA Replication, one strand of DNA serves as the “template” to build the second strand of DNA  The replicated strand would look like this

22.  Replication of DNA  There are 3 steps in the replication of DNA  In your group, assign a step to each member  Use pages 198 – 199 to describe your step in your own words  Each member will also describe how DNA “checks for errors”  Share each step in order once the whole group is finished

23. Result: 2 new DNA double helixes created (identical to each other and original DNA)

24.  What two enzymes play an important role in DNA replication?  What is the purpose of DNA polymerase in the “proofreading” role?  What is the result of DNA replication?

25.  What occurs in the first step of DNA replication?

26.  Gene Scene Gene Scene  DNA Workshop DNA Workshop  The Geee! In Genome The Geee! In Genome  Putting DNA to work Putting DNA to work  Kids Genetics: DNA Kids Genetics: DNA  Hershey and Chase Experiment Animation Hershey and Chase Experiment Animation  DNA Replication Animation DNA Replication Animation  Another DNA Replication Animation Another DNA Replication Animation