1. California Content Standards
DNA
Ms. Garcia
LN #21
California Content Standards
Genetics
5a. Students know the general structures and functions of DNA, RNA, and protein.
5b. Students know how to apply base-pairing rules to explain precise copying of DNA during semiconservative replication and transcription of information from DNA into mRNA.

2. Chromosomes & DNA……….. Chromosomes are made of DNA and protein.
deoxyribonucleic acid (DNA)
The total DNA in our 46 chromosomes would stretch for 3 meters.
The reason all this DNA fits in our cells is because of the way DNA is coiled in our chromosomes.
Our chromosomes contain 20,000 to100,000 genes, this makes up 10% of our DNA.
90% of our DNA does not code for traits.

3. Double Helix Double Helix
DNA’s shape was first described in 1953 by Watson and Crick.
Rosalind Franklin was the first to take an X-ray photograph of DNA.
Watson and Crick described DNA as a double helix.

4. What is a Nucleotide? DNA is made of nucleotides.
Nucleotides are repeating subunits that make up DNA.
Nucleotides contain 3 parts.
phosphate group
sugar (deoxyribose)
nitrogen base 2 3 1

5. Base Pairing Rules DNA contains 4 types of nitrogen bases.
Purines
Pyrimidines
DNA contains 4 types of nitrogen bases.
The nitrogen bases are categorized in 2 groups.
Purines
Adenine (A)
Guanine (G)
Pyrimidines
Thymine (T)
Cytosine (C)
A always bonds with T
G always bonds with C
Too big
Too small
Just right

6. Genetic Code
Deoxyribose and the phosphate group make up the backbone of the DNA strands.
The nitrogen bases form a code that contains the instructions for making proteins.
Our bodies read DNA’s code to express our traits.
DNA is located in the nucleus of cells.

7. DNA Replication
Every cell in our body, with the exception of red blood cells, contain DNA.
DNA replication ensures that every cell will have the correct amount of DNA after meiosis and mitosis have been completed.
DNA replication takes place during interphase.

8. Summary What are chromosomes made of? What is a nucleotide?
What are the three parts of a nucleotide?
What is the general structure of DNA?
What are the base pairing rules of DNA?
Why is DNA replication important?
Do Pre Reading 11.1 on page 287.