DNA Extraction Laboratory Complete

7/21/2019 DNA Extraction Laboratory Complete

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DNA Extraction Laboratory Exercise Name:___________________________________ Period:_______

We will participate in a laboratory exercise in which you will attempt to extract DNA from

several different organisms. Even though DNA is found in virtually every cell a living organism,

it can be difficult to extract from cells.

You are to read the following background information and instructions before you conductyour our laboratory exercise:

Strawberries

Technically, strawberries aren't berries at all. They're "aggregate fruits": they form

from a flower that has many ovaries.

To explain: the ovary is the part of a flower that ripens into a fruit. While some flowers

have one ovary, other flowers, like the strawberry flower, have many.When a strawberry

flower is pollinated (by bees and their friends), the ovaries swell and form what's called the

fleshy receptable -- the red, juicy part you eat. (The tiny "seeds" on the outside are actuallycalled achenes. Inside each achene is a seed. The green leafy crown at the top is the calyx.)

Since an aggregate fruit forms from more than one ovary, it's called a complex fruit.

Raspberries (aggregate fruit), blackberries (ditto) and mulberries (multiple fruit) are also

complex fruits.

True berries, on the other hand, are a type of simple fruit: they form from a flower

that has just one ovary. The inside of a berry is soft and mushy and usually has more than one

seed. Grapes, tomatoes and cranberries are berries. So are bananas!

Some species of strawberry are diploid, having two sets of the seven chromosomes (14

chromosomes total). Others are tetraploid (four sets, 28 chromosomes total), hexaploid (six

sets, 42 chromosomes total), octoploid (eight sets, 56 chromosomes total), or decaploid (tensets, 70 chromosomes total).

Ripe strawberries produce large amounts of pectinases and cellulases which function by

breaking down components in the cell wall (pectin and cellulose). This may explain the relative

softness of ripe fruit in relation to unripe fruits. (from: http://extension.osu.edu)

Bananas

The term banana is applied to both the plant and its elongated fruit. The Banana itself

is from the berry family. A berry is a simple fruit having a skin surrounding one or more seeds

in a fleshy pulp. Bananas can be either Diploid or Triploid (44 or 66 chromosomes). The little

black dots in commercial bananas are abortive seeds that did not fully develop. A diploid

banana is smaller and contains many large hard seeds about the size of coffee beans.

Bananas have 22 chromosomes per haploid set.

(From:

http://seattlecentral.edu/faculty/mboyle/BIO101/Lab%20Exercises/BIO101_lab_14.pdf.)

http://seattlecentral.edu/faculty/mboyle/BIO101/Lab%20Exercises/BIO101_lab_14.pdf





Pre-lab Questions

Some of the following questions can be found in your science book, the background information for this lab,while others you may have to look up in a dictionary (or even the internet).

1. What is the importance of DNA? (In other words, what role does DNA play in life?)

2. Where is DNA found in Eukaryotic organisms?

3. Name the four Base Pairs Found in DNA.

4. Cells contain four very important Organic Compounds. Name them:

5. Cell membranes are made up by three of the four compounds named in question #4. Which of the four

makes up most the cell and nuclear membrane?

6. DNA is a long thread that is wrapped around a group of organic compounds that protects and organizes the

DNA and results in the formation of Chromatin. What is this organic compound the DNA is

wrapped around?

7. DNA is called a double helix because it is made up of two strands. The strands are joined together by

certain nucleotides pairing-up. Which bases can pair up with each other?

8. If humans have a diploid number of 46, what is the haploid number and the triploid number for humans?

For the two following questions, you may have to use a dictionary or the internet to answer.

9. What does “Extraction” mean?

10. What does “Solubility” mean?

11. What does “Interface” mean (in relation to two liquids)?



Lab Instructions for Extraction of DNA .

1. Take one of the plastic bags on your lab tray and find the mass and record it on

your lab sheet (to be given out in class the day of the lab).

2. Place one of the substances (Banana or Strawberry) into the bag and find it’s

mass and record it on your lab sheet.

3. Repeat for the remaining substance.

4. Add about 6 ml of the salt solution (6% NaCl) to each bag, and seal the bags.

5. Mash-up the substances real well, try to break up any large chunks, make sure

that you make a “mush” of the materials (like baby food).

6.

Carefully open up the bags and add about 1 ml of the detergent solution to each

bag. Seal the bags and GENTLY mix the “mush” with the detergent. Avoid

producing bubbles or foam.

7. Add ~1 g of meat tenderizer and gently mix.

8. Carefully hold the baggie by one of the upper corners so that the “mush”

accumulates in a corner of the baggie. Carefully pour or trickle down about

10-20 ml of alcohol down a side crease of the baggie. The alcohol shouldform a layer on the top.

9. Observed any materials that appear at the interface and then make a sketch of

the bag.

10. Very carefully, try to spool the material on a rod (plastic, glass, or wooden).

11.

Make a sketch of the spooled material.

12. Take each of the spooled material and place it onto a piece of filter paper (side

by side). Which substance yielded the most DNA?

Lab modified from “DNA Extractions – A Starting Point for Biochemical Inquiry”, by Karen E. Kalumuck .

Exploratorium Teacher Institute.



Data Table and Observation

Weight of PlasticBag

Weight of PlasticBag + Strawberry

Weight ofStrawberry

Weight of PlasticBag

Weight of PlasticBag +

_____________

Weight of

_____________

Sketch of bag with strawberry sample after the

addition of alcohol.Sketch of bag with ___________sample after theaddition of alcohol.



Post Lab Questions

1. Which of the two (strawberry or banana) did you expect to yield more DNA? How did you

come up with this prediction?

2. Which of the two (strawberry or banana) actually yielded the most amount of DNA? Why do

you think that occurred?

3. Meat tenderizers contain one of two enzymes: Bromelain and Papain. Bromelain is a mixture

of protein-digesting (called proteo lytic ) enzymes found in pineapples. Papain is also aproteolytic enzyme, but instead of being found in pineapples, it is found in papayas. Why is

meat tenderizer used in your lab to help you extract DNA?

4. Soap is a substance that is used to break down lipids and make them more water soluble.

Why do you think we used a soap solution to help us extract DNA from our substances?

5. After adding and mixing the soap solution with your samples, what was the purpose of

filtering the samples?

6. Why was it important that the alcohol we used was of a high percentage (91%) and very cold

to help us extract the DNA from our samples (what is DNA like in alcohol and why such a high

percentage)?

DNA Extraction Laboratory Complete

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