KEY CONCEPT DNA structure is the same in all organisms.

1. KEY CONCEPT DNA structure is the same in all organisms. Why is this mouse glowing? GFP- green fluorescent protein glowing jellyfish virus infected mouse egg mouse genes

2. What is DNA? • One type of nucleic acid • Deoxyribonucleic acid • Overall shape: known as Double Helix (spiral staircase) • What does DNA do? • Stores and transmits genetic information • Tells cells which proteins to make and when

3. phosphate group nitrogen-containing base deoxyribose (sugar) DNA is a long chain of NUCLEOTIDES Each nucleotide has three parts. • a nitrogen-containing base (ladder rungs) • a phosphate group • a deoxyribose sugar make up backbone

4. Nucleotides: Phosphate – Sugar – Base 4 Kinds of Bases: Pyrimidines Purines Thymine Adenine Cytosine Guanine Base Pairing Rules: A pairs with T G pairs with C

5. The nitrogen containing bases are the only difference in the four nucleotides.

6. G C A T Nucleotides always pair in the same way. • The base-pairing rules show how nucleotides always pair up in DNA. • A pairs with T • C pairs with G • Because a pyrimidine (single ring) pairs with a purine (double ring), the helix has a uniform width.

7. covalent bond hydrogen bond • What types of bonds do you think form between: • the bases? • the phosphates and the sugars? • Explain your answer.

8. covalent bond hydrogen bond • The bases are connected by hydrogen bonds. • The backbone is connected by covalent bonds. What molecules are the hydrogen bonds between? What molecules are the covalent bonds between?

9. covalent bond hydrogen bond C A B D: Which letters in the model (A,G,T,or C) represent purines? Which represent pyrimidines?

10. Watson and Crick determined the three-dimensional structure of DNA by building models. • They realized that DNA is a double helix that is made up of a sugar-phosphate backbone on the outside with bases on the inside.

11. Now for DNA Replication…

12. KEY CONCEPT DNA replication copies the genetic information of a cell.

13. nucleotide The DNA molecule unzips in both directions. What is DNA replication? 1.) Enzymes unzip the double helix in 2 directions Point of separation = ____________________ What enzyme causes helix to separate? ____________________

14. nucleotide new strand DNA polymerase • DNA polymerase bonds new nucleotides together. • -moves along chain, assembles new chains • Nucleotides pair with exposed bases on template • -bases join together by hydrogen-bonds -sugar-phosphates join together by covalent bonds

15. new strand original strand Two molecules of DNA 4. 2 new molecules of DNA are made New strand is complimentary to the original. If old strand is: A T T C C G T New strand is: __________________

16. There are many origins of replication in eukaryotic chromosomes. Replication is fast and accurate. • DNA replication starts at many points in eukaryotic chromosomes. • DNA polymerases can find and correct errors.

17. What are the monomers that are strung together to make a DNA molecule? • A. sugar-phosphates • B. nucleotides • C. nitrogenous base pairs • D. amino acids

18. The four types of nucleotides that make up DNA are named for their A. hydrogen bonds B. ring-shaped sugars C. phosphate groups D. nitrogen-containing bases

19. Which of the following DNA sequences is complementary to the base sequence ACCGTAT? • GTTACGC • UCCGTAT • TGGCATA • CAATGCG

20. What holds base pairs together? • Hydrogen bonds • Sugar-phosphate backbones • Pairs of double-ringed nucleotides • Nitrogen-carbon bonds

21. What are the main functions of DNA polymerase? • Breaks hydrogen bonds and exposes bases • Holds DNA strands apart and attracts bases • Zips and unzips the double-stranded DNA • Binds nucleotides and corrects base pair errors