Lab 1do Strawberries Have Dna?

Question 1

When and who determined the structure of DNA?

Answer 1

James Watson and Francis Crick determined it in 1953.

They determined it 2as a double helix consisting of two anti-parallel strands

-it’s often described as a spiral ladder

Question 2

What is the role of DNA?

Answer 2

• replication, provides information to copy itself, so genetic information can be passed on from generation to generation of cells
• DNA provides instructions for making proteins, wh8ch are vital to the maintenance and function of cells. DNA prov8des information for the order of amino acids required for making various proteins

Question 3

What are the base pairs of DNA?

Answer 3

Adenine pairs with Thymine

-cytosine always pairs with Guanine

The bases are held together by hydrogen bonds

Question 4

How and why can DNA be extracted and spooled?

Answer 4

DNA can be extracted from cell nuclei by adding an aqueous buffered extraction solution to cells.

The cells are chemically lysed and the DNA from chromosomes is released. This procedure is known as cell lysis.

DNA is soluble in water and cannot be seen, but it is insoluble in alcohol.

Purification of the nucleic acids usually include precipitation with alcohol in the presence of salt.

The amount of DNA spooled is a consequence of the size of the DNA fragments which are much larger than the small bio-molecules such as amino acids and small carbohydrate sugars

Question 5

Why will isopropyl alcohol form a second layer above the DNA solution?

Answer 5

Isopropyl alcohol has a lower density than water, thus it will form a second layer above the DNA solution

Question 6

How can DNA be separated from the two layers?

Answer 6

A spooling rod is used to spool the two liquids at the interface of the two phases to separate the DNA from the solution

Question 7

Why spectrophotometry can quantification of DNA?

Answer 7

Used to access the concentration of a. DNA sample

• the nitrogenous bases in nucleotides have an absirption maximum at 260 Na
• the more light absorbed by the sample, the higher the nucleic acid concentration in the sample
• the absorbance at 260 nm in a 1cm fuvette of a 50 ug/ML solution of a double stranded is equal to 1

Question 8

Summarize the steps of DNA extraction

Answer 8

You are given a test tube containing a strawberry

2. Mince the strawberry using a glass rod. This will release the cellular contents and the DNA from the strawberry cells..
3. Add 5ml of DNA extraction buffer to the test tube containing the sample and invert several times, mixing the buffer and the sample
4. Layer the cheese cloth square on top of clean 250 ml beaker and attach using a rubber band
5. Pour the fruit mixture into the cheesecloth and allow the liquid to collect in the beaker. Note: Do not squeeze the cheese cloth
6. After all the liquid has been collected, carefully remove 2ml from the beaker and transfer it into a clean test tube
7. From the 2ml transferred, remove 200 uL of extract to a micro tube labeled E1

Question 9

Explain the steps of DNA spooling

Answer 9

1. Holding the test tube at a slight angle, carefully transfer 4ml of very cold 70% clear isopropyl alcohol down, the side of the test tube containing the remaining 1800 uL,so that the alcohol forms a second layer on top of the solution. Ensure that you are using cold alcohol
2. Gently place a spooling rod into the interface containing the DNA by turning the rod in one direction- the DNA will “wind” itself onto the rod
3. Carefully lift the rod out of the solution from time to time to observe the DNA attached to it
4. After spooling first several minutes, remove the rod from the test tube to observe the DNA. It will appear as a viscous material adhering to the rod

Question 10

What are the steps to DNA quantification?

Answer 10

1. Transfer 5 ul(from E1) to a clean micro tube labeled E2
2. Carefully add 495 uL of distilled water to the micro-tube E2. This will result in a dilution of your DNA sample
3. Mix the solution using the vibrating vortex mixer to ensure that the DNA is uniformly mixed into the water.
4. You will then take your dilute samples to the IV spectrophotometer, which contains a Blank sample(curettes containing distilled water)
5. Take a pen and paper to write down the absorbance value of by our DNA sample
6. After measuring the absorbance of your sample, use the formula previously mentioned to calculate the concentration of your DNA sample