Question

DNA Extraction Watch DNA extraction video DNA Modeling Post-laboratory questions: New lab manual page 44 1. Why do we use a commercially grown fruit in this case strawberries) for our DNA extraction? 2. What does the detergent accomplish in a DNA extract? 3. What does the salt accomplish in a DNA extract? 4. What does the addition of rubbing alcohol isopropanol) accomplish in the DNA extract? 5. Why does the solution become viscous after the addition of shampoo (detergent)? Students will also study DNA models and draw the nucleotide molecules that make RNA and DNA. 1. What are the differences between DNA and RNA? 2. Outline the process of DNA synthesis? 3. How can arrangement of 4 different bases in DNA code for millions of different proteins? 4. What are the 3 component parts of a nucleotide? 5. Name the 4 bases in DNA? 6. Name the 4 bases in RNA? 7. What bases in DNA and RNA pair together?

Answer 1

I

1. Usually, ripened strawberries are used for DNA extraction. They contain enzymes like pectinases and cellulases. These enzymes help to break the cells easily. Also, strawberry has 8 copies of each chromosome. So there will be a huge amount of DNA available to extract.

2. Detergent in DNA extract helps to remove the lipids and other kinds of proteins present in the cells. These are usually present in the cell and nuclear membrane.

3. The salt is DNA extract helps to neutralize the negative charge of DNA.

4. Isopropanol helps to precipitate different proteins. It can also be used to precipitate DNA from large volumes.

5. We know that detergent helps to settle down all the proteins and lipids in the solution. Usually, viscosity is produced due to the interaction between molecules. So the answer is clear.

II

1.

• DNA is double-stranded. RNA is single-stranded.
• DNA has Adenine, Thymine, Guanine, and Cytosine. RNA has Adenine, Uracil, Guanine, and Cytosine
• There are different types of RNA. There is one type of DNA.
• DNA has Deoxyribose sugar. RNA has Ribose sugar

2.

DNA is synthesized from pre-existing DNA by a process called semiconservative replication. Here one parent DNA will synthesize two new DNA and each DNA will have one parent strand and a daughter strand. The replication begins at a position called the origin of replication (ori site). The DNA unwinds to form a Y shaped replication fork. In this strand 3'-5' is called the leading strand. Replication takes place normally here using DNA dependent DNA polymerase in direction 5'-3'. The strand 5'-3' is called the lagging strand and replication of this strand takes place by the synthesis of Okazaki fragments. These fragments are joined by ligases.

3.

The 4 different bases in the DNA form a group of 3 bases. These are called codons. Each codon will code for an amino acid.

4.

The components are:

• A pentose sugar
• A nitrogen base
• A phosphate group

5.

Adenine, Thymine, Guanine, and Cytosine

6.

Adenine, Uracil, Guanine, and Cytosine

7.

DNA

• Adenine - Thymine (2 H bonds)
• Guanine - Cytosine (3 H bonds)

RNA

• Adenine-Uracil (2 H bonds)
• Guanine- Cytosine (3 H bonds)