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Activity 12:

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Alexandra Cates Erika Suyo

on 18 August 2013

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Transcript of Activity 12:

Activity 12: Examining DNA and RNA in Onion Cells
Activity 12:
DNA - Deoxyribonucleic acids
- constitutes our genes
RNA - ribonucleic acids
- involved in protein synthesis.

They are:
- nucleic acids found in cells.
- carriers of genetic information.

Question 1. Describe what you have observed.
The onion cells were stained in pink and blue-green shades. The onion cells were elongated.
Question 2. In which parts of the cell are DNA located?
Question 3. In which parts of the cell are RNA located?
rRNA (ribosomal) is located in the ribosomes that they make up, mRNA(messenger) can be found on ribosomes, or in the nucleus depending on what process it is going through. Also, tRNA(transfer) can be found in the nucleus of eukaryotic cells.
Question 4. What are the functions of DNA and RNA?
Procedure
A. Preparing the onion scales for microscopic study
1.Get a young scale from the onion bulb.

2.Cut about the 7mm square sections on the concave surface of the onion scale.

3.Using forceps, remove a thin section and place it on a slide.

B. Fixing the tissue
1.Place 2-3 drops of ethanol on the onion tissue.

2.After 1-2 minutes, remove excess ethanol using filter paper.

3.Then, wash the tissue with a few drops of distilled water. Blot dry the tissue.

C. Staining and Washing the Tissue
1.Add 1-2 drops of methyl green pyronin stain solution to the tissue. Put a cover slip over the tissue.

2.After 5 minutes, wash the tissue with distilled water.

D. Observing the Stained Tissue
1.Add 1-2 drops of methyl green pyronin stain solution to the tissue. Put a cover slip over the tissue.
2.After 5 minutes, wash the tissue with distilled water.
3. Look for the blue or blue-green stained part. This is the DNA.
4. Look for the pink or red stained part. This is the RNA.
5. Draw, color and label the different parts of the onion cell.

DNA can be found in chromosomes located in the nucleus, as well as the mitochondria and chloroplasts
DNA Functions
The primary function of DNA in organisms is to store and transmit the genetic information that tells cells which proteins to make and when to make them.
RNA Function
There are three types of RNA are mRNA (messenger), tRNA (transfer), rRNA (ribosomal).

mRNA (messenger)- The function of mRNA is to carry genetic information from the DNA in the nucleus to the ribosomes of a cell.

tRNA (transfer)- The function of tRNA is to bring the correct amino acid to the ribosomes in the cystosol.

rRNA (ribosomal)- The function of rRNA is to create new ribosomes.
Onion cell under HPO
Results and Discussion

Generalisation
DNA is the molecule that carries all genetic information in a cell. It is located in the cell's nucleus, mitochondria and chloroplast. RNA has a few different functions depending on the type of RNA molecule. It is hugely involved in protein synthesis. RNA is present in ribosomes and the nucleus.
Full transcript