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. 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
phosphate group
deoxyribose (sugar)
nitrogen-containing
base

4. Phosphate – Sugar – Base
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. 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. C G T A

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

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

9. D: Which letters in the model (A,G,T,or C) represent purines?
hydrogen bond
covalent 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. What is DNA replication?
1.) Enzymes unzip the double helix in 2 directions
nucleotide
The DNA molecule unzips in both directions.
Point of separation =
____________________
What enzyme causes helix to separate?
____________________

14. 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
DNA polymerase
new strand
nucleotide

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

16. Replication is fast and accurate.
DNA replication starts at many points in eukaryotic chromosomes.
There are many origins of replication 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