1. CHROMOSOMES & DNA REPLICATION
THE SOURCE OF GENETIC INFORMATION

2. PROKARYOTIC CELLS Prokaryotic Cells =
Lack nucleus and many organelles found in eukaryotes
DNA is found in cytoplasm of prokaryotes
Single circular DNA that has all of cells genetic information, a plasmid

3. EUKARYOTIC CELLS Eukaryotic Cells =
DNA is found in nucleus in the form of chromosomes.
Number of chromosomes varies from one organism to another
Humans have 46, fruit flies has 8 and giant sequoia trees have 22
1000X more DNA than prokaryotic cells: more complex.

4. CHROMOSOME STRUCTURE DNA in Eukaryotes is packed tight.
A human cell contain 1000X more base pairs than 1 bacteria.
Nucleus contains more than 6 feet of DNA.
Eukaryotic chromosomes have both DNA and proteins packed together of from a substance called chromatin
Chromatin consists of DNA that is tightly coiled around proteins called histones.
Histones = proteins that DNA wraps around.

5. DNA Section 12-2 Nucleosome Chromosome DNA double helix Coils
Supercoils
Histones
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6. DNA REPLICATION
Replication = duplicating or copying the DNA before the cell divides.
How is it done?
DNA separates into 2 strands
Then forms new complementary strands (according to base rules).
Complimentary strands ofDNA have opposite bases. For example: A always pairs with T.
If one strand has the base A, then the complimentary strand has T.

7. Each strand of the double helix serves as a template, or model for the new strand.
Replication is carried out by a series of enzyme reactions.
They unzip the double helix and expose the complimentary bases on the inside.
Now they can be copied

8. DNA REPLICATION Section 12-2 Go to Section: New strand Original strand
DNA polymerase
Growth
DNA polymerase
Growth
Replication fork
Replication fork
Nitrogenous bases
Original strand
New strand
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9. HOW DOES REPLICATION OCCUR?
DNA polymerase - enzyme helps unzip DNA.
Weak hydrogen bonds break and strands unwind.

10. REPLICATION

11. DNA replication interactive

12. In your own words: How is DNA replicated?
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