1. Wed 3.6.2013 Review the structure & function of DNA
Today’s Objectives (Write on today’s NOTES!)
Review the structure & function of DNA
Prepare for the DNA extraction lab

3. TAKE NOTES! Nucleus; in eukaryotes Double Helix 4 base pairs (A,C,G,T)
Chromatin which condenses into chromosomes

4. Cell wall (only in plants)
2. Nuclear Membrane
3. Cell Membrane

5. To extract the DNA ….. Which parts of the cell do you have to go through to remove the DNA?
BARRIERS TO OVERCOME
BARRIER 1: Cell Wall (only in plant)
BARRIER 2: Cell membrane
BARRIER 3: Nuclear membrane 5

6. BARRIER 1 - Cell Wall Mashing/Crushing
EXTRACTION PROCEDURE
ACTIVITY FUNCTION
Mashing/Crushing
This breaks open the cell (LYSE) wall, cell membrane, and the nuclear envelope to allow the DNA to be released. 6

7. Breaks open the cell wall

8. BARRIER 2 – Cell Membrane & BARRIER 3- Nuclear Membrane
EXTRACTION PROCEDURE
ACTIVITY FUNCTION
Detergent (buffer)
Breakdown the fat and proteins that make up the cell and nuclear membrane. (Just like the detergent dissolves grease on your dishes). 8

9. Cell Membrane
What components make up the membrane that surrounds the cell?
REMEMBER
Cell membranes are made of phospholipids 9

10. Cell Membrane Phospholipids are bi-layer, with a head and a tail.
HATES Water:
HYDROPHOBIC
Phospholipids are bi-layer, with a head and a tail.
the head –LOVES WATER
the tail – HATES WATER
Phospholipids won’t dissolve in water
LOVES Water:
HYDROPHILIC 10

11. Why am I adding Detergent?

12. Breaks open the cell
Breaks open the cell membrane and nuclear membrane

13. Protein wrapped around DNA
EXTRACTION PROCEDURE
ACTIVITY FUNCTION
Meat tenderizer (Enzyme)
Adding an enzyme, such as meat tenderizer will break down proteins such as nucleases and histones that are wound around the DNA. 13

15. Breaks open the cell
Breaks open the cell membrane and nuclear membrane
To cut proteins away from the DNA

16. Filter EXTRACTION PROCEDURE Filter Separate the components of the cell
ACTIVITY FUNCTION
Filter
Separate the components of the cell 16

17. Breaks open the cell
Breaks open the cell membrane and nuclear membrane
To cut proteins away from the DNA
Organelles, broken cell wall, membranes from proteins, carbohydrates

18. Last Step! EXTRACTION PROCEDURE
ACTIVITY FUNCTION
Alcohol
DNA does not dissolve in alcohol. (It is soluble in water).
The addition of alcohol causes the DNA to precipitate. 18

19. Cold slows down molecules helping them clump together
Alcohol is a weak polar solvent—causing insoluble DNA to separate out

20. DNA Extraction Protocol
Just follow these 3 easy steps:
DNA
eNzymes
(meat tenderizer)
Alcohol
Detergent
Dissolve cell membranes Break down proteins Precipitate DNA 20