1. Chromosomes and DNA Replication
Vocabulary:
Chromatin
Histone
Replication
DNA polymerase
Key Concept:
What happens during DNA Replication?

2. Eukaryotic cells are different from prokaryotic cells because…
They do not have DNA
They do have DNA
They have a nucleus
They do not have a nucleus

3. The Review Eukaryotic cells have a nucleus
Can have 1000x more DNA than prokaryotic cells
DNA is located in the form of a number of chromosomes
The number of chromosomes is different for different kinds of animals and plants

4. DNA Length DNA molecules are LONG!
Ex: E. Coli (prokaryote that lives in human colon) has 4,639,221 base pairs
This equals approximately 1.6mm
BUT bacteria are SMALL (1.6um in diameter)
It’s like putting a 300m rope into a backpack

5. How Does DNA Fit? Form a chromosome! Chromatin = DNA+ proteins
DNA coils around proteins called histones and then this chromatin coils again around itself
These coils and coils are the visible chromosome (that you can see!)

6. The “X” shaped structure that is visible during cell division is (a)…
Chromatid
Chromatin
Mitosis
Chromosome

7. Review
1) How do long DNA molecules fit in a cell?

8. DNA Replication
Before a cell divides, it must copy its DNA so that all cells have a copy of the genetic instructions
This process involves A LOT of enzymes!
 Each half of the DNA double helix can serve as a "template" for the replication of another DNA double helix molecule
The strands are said to be complementary

9. The complementary base pairs are:
A-G and C-T
A-T and C-G
A-B and C-D
A-A and G-G

10. Hydrogen Bonds Breaking!
THE PROCESS
An enzyme unwinds & "unzips" DNA (separates the 2 DNA strands) by breaking the Hydrogen bonds between base pairs
Hydrogen Bonds Breaking!

11. the complementary base is inserted to each side of the DNA strand with the help of DNA Polymerase
Why does the “blue” always pair with the “green?”

13. 1 nucleotide
The sugar-phosphate groups are covalently bonded to the growing DNA chain (new "backbone")
COVALENT BOND

14. an enzyme (DNA Polymerase) will "proof-read" the order of bases & make corrections/ changes if there were any problems

15. SIMPLIFIED VERSION…
                                 

16. A Little More Complicated…

17. The backbone of DNA is made up of which parts of the nucleotide?
5-carbon sugar
5-carbon sugar and a nitrogenous base
Phosphate group and a nitrogenous base
5-carbon sugar and a phosphate group
Phosphate group

18. What weak bond holds the strands of DNA together?
Hydrogen Bonds
Covalent Bonds
Ionic Bonds
Peptide Bonds

19. Review
Summarize the stages of DNA replication 1) 2) 3) 4)