1. Chapter 9, Section 2 & 3 Regular Biology
DNA- Replication
Chapter 9, Section 2 & 3 Regular Biology

2. Objectives Describe structure of DNA Explain importance of DNA
Understand why living things need to make copies of DNA
Describe how copies of DNA are made
Explain what happens if a mutation occurs in replication

3. Deoxyribose Nucleic Acid
Structure of DNA
Deoxyribose Nucleic Acid
Double helix
Made of 2 strands of nucleotides
Phosphate
Sugar (deoxyribose)
Nitrogen Base
Adenine (“A”)
Thymine (“T”)
Cytosine (“C”)
Guanine (“G”)
Nucleotide

5. About DNA TATGGAGAGTC ATACCTCTCAG Sugar & Phosphate make up the sides
In the middle of DNA
Adenine pairs with Thymine (A-T)
Cytosine pairs with Guanine (C-G)
Practice:
TATGGAGAGTC
ATACCTCTCAG
Complementary base pairs

6. More Practice CATAAGTCCT ATTGTCT CTAATGT 1. GTATTCAGGA 2. TAACAGA
3. GATTACA
CTAATGT

7. Names to Know, pg 196 Chargaff- (1949) A pairs with T. G pairs with C
Mrs. Franklin- (1952) X-ray pictures of DNA
Watson & Crick- (1953) DNA is double helix

8. Prokaryote DNA is: Prokaryote DNA is circular Has 2 replication forks
Replication occurs in opposite directions around the circle until they meet
Can replicate in 1 hour or less

9. Eukaryote DNA is: Eukaryote DNA is double stranded
Compacted in chromosomes
Each chromosome can have about 100 replication forks
Each “new” DNA strand is about 100,000 nucleotides long.
The DNA in your body would wrap around the Earth about 1.5 times!
Takes about 8 hours to replicate human chromosomes in Interphase

11. Prokaryote vs Eukaryote

12. Prokaryote vs Eukaryote DNA
Make a Venn Diagram
Prokaryote vs Eukaryote DNA

13. Replication- Making more DNA Happens in the nucleus
What?
Replication-
Making more DNA
Where?
Happens in the nucleus
When?
Occurs during Interphase
S (synthesis) phase
Occurs whenever is needed

14. Replication- Making more DNA
Why?
Important for Mitosis and Meiosis
Mitosis- new cells for growth & repair
Meiosis- new cells for sperm & egg
Important for making more copies of a protein, enzyme, etc

15. Replication- making more DNA
Two strands separate, forming replication fork
DNA polymerase (an enzyme) brings bases to make “new” strands
500/sec in bacteria, 50/sec in humans….WOW!
Half of DNA strand is “old” and half is “new”
Result: two strands of DNA form that are identical to the original molecule

17. But what if there’s a mistake?
Types of Mutations
Frameshift- (the new part of DNA shifts to be longer or shorter than it should be)
Deletion
Correct base is deleted
Insertion
Incorrect Base is added
Point mutation (base pair substitution)
Wrong base pair is stuck in the place of another

19. Build-in Mutation Reducers
Replication has “proof-readers” to help reduce errors
DNA polymerase
Chaperone proteins
These proteins and enzymes reduce errors to about 1 error for every 1 billion nucleotides.

20. But what if a mutation DOES happen?
DNA RNA Protein
(Genes)
(Enzyme)
Discussion!

21. Genetic Technology- Terms to Know
Genetic engineering-
Recombinant DNA- DNA made from 2 or more organisms
Vector- What gets the gene into the cell
Usually a virus, yeast, or plasmid
Plasmid- circular bits of DNA
Restriction enzymes- proteins which cut the DNA at specific points

22. New Technology
Human Genome Project- mapping entire human genome sequence. Finished in 2003.
Cloning- process used to creating identical copy of organism
Polymerase Chain Reaction (PCR)- process that makes more DNA
DNA Fingerprinting- use gel electrophoresis to separate DNA of different lengths

23. Genetic Engineering Information
Gel Electrophoresis
Uses electric charges within gel
DNA is negative, thus travels to positive end
Separates molecules by size

24. More New Technology
Genetically Modified Foods- genetically selecting certain traits for crop improvement
Transgenic Animals- Animals that have other DNA in their cell. Used to make proteins, medicine, etc.
Gene Therapy- insert genes into organism to help stop or prevent disease

25. “There is no gene for Human Spirit!”
Remember…
“There is no gene for Human Spirit!”