1. Bell Ringer 3.18 Describe DNA. (structure)
What does DNA do for a cell?
What does DNA do for your body?
Where is DNA located?

2. DNA Structure and Function

3. Deoxyribonucleic acid
DNA
Deoxyribonucleic acid

4. Where is DNA in our cells?
Do all of your cells have the same DNA?

5. If all of these cells have the same DNA, why do they look different?

6. Each cell expresses/uses only the DNA that is related to its function.
Ex: the function of the RBC is to use hemoglobin to transport oxygen. The genes that code for the protein hemoglobin are located on chromosomes 11 and 16. Even though ALL cells have these chromosomes, ONLY RBCs use the sections of these chromosomes that code for hemoglobin.

7. So, now that we know where DNA is located, what is DNA?
Composes chromosomes (and genes)
A type of organic compound called a nucleic acid
Made up of repeating nucleotides
REMEMBER, the monomer/subunit for Nucleic Acids is a nucleotide!

8. 1 nucleotide looks like:
4 types of nitrogenous bases:
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

9. Base pair rule: A binds to T ONLY C binds to G ONLY
There are 2 strands so bases have to pair up.
Base pair rule:
A binds to T ONLY
C binds to G ONLY
Stand #1
Stand #2

10. What holds the strands of DNA together?
Sugar-phosphate bonds hold the nucleotides together and hydrogen bonds connect the bases to each other.
G  C  three hydrogen bonds
A = T  two hydrogen bonds

11. The two strands of nucleotides twist together forming a double helix.
James Watson and Francis Crick interpreted the photo and discovered how the nucleotides fit together (they won the Nobel Prize).
Rosalind Franklin took an X-ray photo of DNA.

12. DNA is complementary
This means bases on one strand match up with the bases on the other strand (A  T and G  C) Example: Strand 1: ATG GGC CTA Strand 2:

13. DNA Model Pick a partner Get supplies Read directions!
1 packet, 1 direction/questions sheet, scissors, & a glue stick.
Cut out the following:
10 deoxyribose sugars
8 phosphates
8 alternating bases
Read directions!
Answer questions & staple model w/answers together. CLEAN UP!