1. DNA Replication Notes

2. Let’s clear somethings up.
DNA stands for deoxyribose nucleic acid
It is a double strand in the shape of a spiral called Double Helix.
Both strands are held together by hydrogen bonds (weak bonds).
Both strands run in opposite directions. This is called anti-parallel
It is made up of nucleotides
The three parts of nucleotides are
Sugar
Phosphate
Nitrogenous Bases (Adenine, Thymine, Guanine, Cytosine)
DNA holds the instructions to build different cells in our body—the same DNA is repeated in all cells.
The instructions are coded in the order or sequence of nitrogenous bases.

5. DNA Replication
Before a cell divides, the DNA strands unwind and separate
Each strand makes a new partner by adding the appropriate nucleotides
The result is that there are now two double-stranded DNA molecules in the nucleus
So that when the cell divides each nucleus contains DNA
This process is called replication

6. BLAST FROM THE PAST
In which phase of the cell cycle does the DNA replicate?
A- G1
B- S
C- G2
D- M

7. Enzymes involved in DNA replication
DNA Helicase—unzips the DNA by breaking the hydrogen bonds between the nucleotides apart.
DNA Polymerase– builds a new polymer of DNA by adding nucleotides to both sides

8. The original strand separates when DNA Helicase breaks down the hydrogen bonds

9. DNA Polymerase adds nucleotides to each old strand to form two identical strands

10. DNA Polymerase adds nucleotides to each old strand to form two identical strands

11. A preview of next week…
Every three nitrogenous bases codes for a protein that builds your traits! So it’s the bases that carry the genetic code! They also have the code to synthesize enzymes from organic molecules to help build and breakdown products and substrates.

12. What determines the traits of an organism?
The order and sequence of the nitrogenous bases

13. Proofreading New DNA
DNA polymerase initially makes about 1 in 10,000 base pairing errors.
Enzymes proofread and correct these mistakes
The new error rate for DNA that has been proofread is 1 in 1 Billion base pairing errors