1. Take out paper for notes Answer the following questions at the beginning of your notes
Don’t look up the answers…make an educated guess!
What do the letters DNA stand for?
What is DNA made of?
Where can you find DNA?
If your index cards are done, turn them in today for 2pts EC, otherwise they are due tomorrow.
Turn in your 2 worksheets that were due Mon if you didn’t already

2. Ch. 11 DNA and Genes  History of DNA
1800’s Mendel determined that offspring inherited traits from parents
1944 Biomolecule that was involved with heredity was DNA (originally proteins were thought to pass on traits because DNA was too simple)

3. Rosalind Franklin and Maurice Wilkins took diffracted photographs of DNA
X-rays were passed through DNA crystals, the X-rays were bent by the atoms in the DNA molecule producing an image of the shape

4. 1953 Watson & Crick developed a model of DNA using the diffraction photographs taken by Rosalind Franklin
Double Helix = DNA comes in 2 long strands that wrap around each other, “spiral staircase”

5.  Why is DNA so important?
DNA is known as “blueprint of life”
DNA contains instructions for making proteins within the cell
Genes are on our chromosomes, chromosomes are made of DNA

6. Important for all life on Earth, makes each individual plant or animal unique
Helps us understand diseases better & find potential cures
Better food crops

7.  DNA Nucleotides
DNA is a nucleic acid made from subunits called nucleotides
Nucleotide = 3 parts: 1. five-carbon sugar, 2. phosphate group, 3. nitrogenous base
Deoxyribose = the 5-C sugar in a DNA nucleotide

8.  How the Double Helix stays together
phosphates
Double Helix has two strands that twist together
One strand of DNA is like one half of a zipper
The backbone of the molecule is alternating phosphates and deoxyribose sugar
The teeth are nitrogenous bases
deoxyribose
bases

9.  Compare/contrast the nitrogenous bases in a space in your notes
One strand of DNA (half of a zipper) is a polymer of nucleotides
Remember:
Nucleotide = 3 parts: 1. five-carbon sugar, 2. phosphate group, 3. nitrogenous base
One strand of DNA has millions of nucleotides
Do the following:
 Compare/contrast the nitrogenous bases in a space in your notes

10.  Nitrogenous (Nitrogen) Bases
DNA has four different bases
Cytosine C
Thymine T
Adenine A
Guanine G
You will need to memorize these!!
Last slide for per. 3

11. 2 categories of Nitrogenous Bases Purines = double ring bases, A and G
Pyrimidines = single ring bases, T and C
Last slide for per. 8

12.  Complementary Bases
Nitrogenous bases on the 2 strands of DNA pair up with one another
Cytosine (C) pairs with Guanine (G) with 3 Hydrogen Bonds
Adenine (A) pairs with Thymine (T) with 2 Hydrogen Bonds

13.  DNA Model