1. Part 2 DNA structure

2. Learning Target
1. Compare and contrast the structure of eukaryotic and prokaryotic chromosomes.
11. Know what a plasmid is and the types of organisms that have them.

3. Prokaryotes
Prokaryotes lack true nucleus and membrane-bound organelles
Prokaryotic DNA
Found in Cytoplasm
1 circular chromosome
Consists of only DNA & plasmids
Copies  then immediately divides
Plasmids
Circular strands of DNA
Separate of Chromosomal DNA

4. Eukaryotes Eukaryotes have a membrane bound nucleus and organelles
Eukaryotic DNA
Found in Nucleus
Many linear chromosomes
Consists of DNA and histones
Copies then cell continues to grow  then mitosis (organizes chromosomes)  and then divides

5. Pro DNA vs Eu DNA Prokaryotic DNA Eukaryotic DNA
Don’t write this! You already have it!!!!
Prokaryotic DNA
Found in Cytoplasm
1 circular chromosome
Consists of only DNA
Copies  then immediately divides
Eukaryotic DNA
Found in Nucleus
Many linear chromosomes
Consists of DNA and histones
Copies then cell continues to grow  then mitosis (organizes chromosomes)  and then divides

6. Learning Target 3. Recognize the structure of a nucleotide.
4. Describe the chemical and structural properties of DNA.
5. Understand base pairing and its role in replication, transcription and translation.

7. Structure of DNA C Monomer = nucleotides Phosphate group 5 C sugar
(Deoxyribose in DNA)
Nitrogen base- 4 possible
Adenine and guanine- purine bases- double ring structure
Cytosine and thymine- pyrimidine bases -single ring structure C

8. Structure of DNA (cont.)
DNA molecule consists of 2 chains of nucleotides
Arranged in a “ladder” configuration
Alternating phosphate and sugar groups
Rungs composed of paired nitrogen bases
Complementary base pairing-purine with pyrimidine
A with T
G with C
“Ladder” coils to form a helix

9. Why A-T/C-G? N H O CH3 Sugar Adenine (A) Thymine (T) Guanine (G)
Cytosine (C)

10. Why purine/pyrimidine?
Purine + Purine: too wide
Pyrimidine + pyrimidine: too narrow
Purine + pyrimidine: width
Consistent with X-ray data