1. DNA Replication

2. What is DNA? Deoxyribonucleic Acid (DNA) DNA is a NUCLEIC ACID
The sugar is DeoxyRibose
DNA is a NUCLEIC ACID

3. Why is DNA important? DNA is like the blueprint for your body!
It is an extremely long strand of directions for all of the proteins that allow living things to function
Think of DNA as the recipe for making proteins

4. Where is DNA found? PROKARYOTES: Found in the cytoplasm
EUKARYOTES: Found in the nucleus

5. How SIMILAR are you to the person sitting next to you?
You are 99% identical to the person sitting next to you!!
The only difference it the ORDER of your NITROGEN BASES!

6. How is DNA STORED in eukaryotes?
The DNA is compacted in the CHROMOSOMES and stored in the nucleus

7. What is DNA made of (the subunits)?
NUCLEOTIDES!!

8. What are the main parts of a NUCLEOTIDE?
Phosphate
Sugar
Nitrogen Base (A, T, C, G)

9. Label the parts of a Nucleotide

10. What are the FOUR NITROGEN BAES?
A = Adenine
T =Thymine
C =Cytosine
G = Guanine

11. What is COMPLIMENTARY BASE PAIRING?
The same bases will ALWAYS pair together!
A pairs with T
C pairs with G
ALWAYS!!! (Unless there is a mutation)

12. TRY IT!
ATT ATC GTA TCT CAT ATG TCG GAT

13. How is a DNA molecule MADE?
Nucleotides come together
Then, HYDROGEN bonds form between the nitrogen bases
This makes TWO strands of nucleotides which twist into a DOUBLE HELIX

14. What is the SHAPE of DNA? DOUBLE HELIX It looks like a twisted ladder
OR, a spiral staircase

15. What are HYDROGEN BONDS?
The bonds that form between the nitrogen bases
They are very WEAK and break easily
This is how DNA is able to make new copies of itself!

16. What is DNA REPLICATION?
NEW cells are made by copying
OLD cells
Before a cell divides, you have to
copy or REPLICATE the DNA
REVIEW!
What stage of the cell cycle does
DNA Replication happen in?

17. When does DNA Replication occur?
During S –Phase of INTERPHASE
S-Phase = Synthesis Phase
The DNA Replicates (copies itself ) to prepare for cell division (MITOSIS!!!)

18. Why does DNA REPLICATE? To get ready for cell division
So each new cell has the same exact DNA!

19. What are the STEPS for DNA Replication?
An Enzyme “UNZIPS” the 2 strands of DNA by breaking the weak Hydrogen bonds
New nucleotides are added to the old stand
REVIEW: A = T and C = G
Another Enzyme “ZIPS” the strands back up
DNA Polymerase (an enzyme) “proofreads” the strands to make sure there are no MISTAKES!
What do you think
might happen if
there are mistakes?!

20. What is the ROLE of ENZYMES?
Enzymes help to:
1. Split the DNA in half
Put DNA back together
Proofread for any mistakes in the base pairs

21. How is DNA Replication SEMI-CONSERVATIVE?
When the DNA copies itself, it always has HALF of the parental (OLD) strand and HALF of the daughter (NEW) strand
In other words: the DNA is HALF OLD and HALF NEW

23. What are MUTATIONS? Changes in the genetic code (DNA)
Can be: positive, negative or neutral
Causes: UV radiation, chemicals, bad DNA proofreading
Can lead to CANCER