012814 Replication and DNA Extraction Hon Bio 13-14

8/12/2019 012814 Replication and DNA Extraction Hon Bio 13-14

1/28


2/28


3/28


4/28


5/28


6/28


7/28


8/28

The Significance of Watson & Crick

Provided an explanation

for how all the parts

of DNA could be

arranged in a mannerthat would allow the

molecule to replicate

itself

1stPart of Central

Dogma


9/28


10/28

The Complimentary Base Pairing Of The Nitrogenous

Bases Is Due To The Number of Hydrogen Bonds


11/28


12/28

During prophase, the supercoils of DNA may be

further condensed into chromosomes


13/28

How Does DNA Copy Itself?


14/28

REPLICATION OF DNA


15/28

REPLICATION DNA molecule uncoils from tightly condensed state,

assisted by DNA Helicase. This unzipping occurs at the

replication fork. Hydrogen bondsbetween nitrogenous bases break

New exposed half-rungs of ladder-like structures are

called TEMPLATES

Free DNA nucleotides in the nucleus are brought into

place by DNA POLYMERASE

Due to complimentary base pairing, only free Adenines canpair with Thymines in the template, only free Guanines can

pair with Cytosines in the template, etc.

DNA Polymerase also proofreads the strands for mis-

paired nucleotides.

The DNA fork is recoiled


16/28


17/28

Why Is It Essential That The Hydrogen Bonds Between

Nitrogenous Bases Be Weak?


18/28

Replication Occurs In Two Directions

Simultaneously


19/28


20/28

Lab: Extraction of DNA

Purpose: To ascertain and appreciate several

properties of DNA based upon the processes

required to extract DNA from the nucleus of a

eukaryotic cell.

Methodology: Proteolytic enzyme extraction

and separation using non-polar solvent


21/28

Wheat Germ

Source of Nucleic Acids

Wheat germ is derived

from the part of the

wheat seed that isundergoing high mitotic

activity


22/28

Lauryl Sulfate

Active ingredient in

dishsoaps

Why necessary to

disrupt the plasma andnuclear membranes?


23/28

Heat

Why is it important to

have heat?

Why is it important not

to exceed 50C?


24/28

Papain & Bromelin

Proteolytic enzymesfound in meattenderizer.

Derived from bromeliadplants (i.e. pineapple)that use these enzymesto ward off parasites

Problem: Meattenderizer also containsnucleases


25/28

Sodium Hydrogen Carbonate

NaHCO3

Disassociated sodium ionsbind to negative aspectsof DNA polymer,

protecting it fromnucleases in meattenderizer

Can produce carbonicacid when it

disassociates. Why mightthis be useful in terms ofpapain?


26/28


27/28

Lab Protocol

Add 45mL tap water to a 100 mL test tube and

place in a hot water bath. Heat until the

temperature of the water INSIDE THE TEST

TUBE is 55C.

DO NOT, AT ANY POINT, EXCEED 60C!

Add 2g wheat germ and 3mL of lauryl sulfate

(detergent) to the 45mL of water in the test

tube. Stir and incubate for 5 minutes


28/28

Lab Protocol 2

After the first incubation, add 2g of Papain(meat tenderizer) and 5mL 1M NaHCO3. Stirand incubate at 55C for 15 minutes.

NEW STEP: Filter the liquid portion of themixture through a coffee filter into a 100 mLbeaker.

Cool the beaker to 25 C in an ice bath When ready, instructor will layer in 20mL iced

ethanol. Let stand 3-5 minutes and observe.

012814 Replication and DNA Extraction Hon Bio 13-14

Documents

Transcript of 012814 Replication and DNA Extraction Hon Bio 13-14