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Extracting Dna From Onions

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Category: Science

Autor: anton 06 November 2010

Words: 405 | Pages: 2

Extracting DNA from Onions:

By Arun R Shrivats

Observations:

Qualitative Observations:

Qualitative Obervations of DNA Extraction Process in Onions

Stage in DNA Extraction Process Qualitative Observations

1. After addition of Dish Soap • Foam formed at the top

• Greenish yellow

• Fluidy

• Opaque

• Odour: Mixture of onion and soap

2. After 5 minutes • Foam formed t the top

• Lime colour

• Fluidy

• Opaque

• Suspended particles

• Odour: Mixture of onion and soap

3. After pouring through a strainer • Lime colour

• Translucent

• Fluidy

• Foam on the circumference

• Odour: mixture of onion and soap

4. After addition of meat tenderizer • Lime colour

• Translucent

• Fluidy

• Foam on the circumference

• Odour: mixture of onion and soap

5. After 5 minutes • Lime colour

• Translucent

• Fluidy

• Foam on the circumference

• Odour: mixture of onion and soap

6. After layering of alcohol on top • Bubbles rising to the top

• Thick layer on the top

• Thick, white stuff formed

• Three layers: 1) top layer – full of bubbles – opaque; 2) middle layer –alcohol– translucent; 3) bottom layer – original mixture - translucent

7. After 1 minute • Bubbles rising to the top

• Thick layer on the top

• Thick, white stuff formed

• Three layers: 1) top layer – full of bubbles – opaque; 2) middle layer –alcohol– translucent; 3) bottom layer – original mixture - translucent

8. Froth • Viscous, mucus-like

• White

• Soapy & full of bubbles

• Opaque

9. Onion mixture • Light yellow

• Very fluidy

• Strong onion odour

• Foam formed at the top

• Opaque

10. Dish soap • Dark green

• Very viscous

• Bubbles trapped inside it

• Foam formed at the top

• Translucent

• Pleasant odour

11. Meat tenderizer • Solid

• Small crystals

• No odour

• White

• Opaque

12. Ethanol or Isopropyl Alcohol • Clear solution

• Strong odour

• Transparent

• Fluidy

13. DNA • Very Viscous, mucus-like substance

• White

• Thick

• Fragile

• Opaque

Discussion:

1. The onion was mixed in the blender so that parts of the onion cells that did not contain DNA were destroyed. This includes the cell membrane, mitochondria and vacuoles. What is left is the DNA, which is protected by the nucleus.

2. The salt was added to the onion and the water because it ionizes phosphate groups in the solution. As a result, the phosphate groups attached to DNA are ionized. This leads to the DNA being free of the phosphate groups.

3. The dish soap was added in order to further break down the cell wall of the onion molecules.

4. The ingredients in the meat tenderizer included sale, dextrose, bromelain, tricalcium phosphate, hydrogenated soybean and cottonseed oil. The specific ingredient used was bromelain. Bromelain is an enzyme used to break down proteins and help in digestion. It is naturally occurring in pineapple plants.

5. The meat tenderizer is used because of its ingredient bromelain. Because bromelain is a protease, it helps in the breakdown of proteins. In this lab, the histone proteins surrounding the DNA are broken down through the use of bromelain. Without the proteins protecting the DNA, the alcohol is able to precipitate the DNA.

6. In this experiment,

Works Cited

http://www.vitacost.com/science/hn/Supp/Bromelain.htm

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