RED ONION OSMOSIS

Introduction: 
In this experiment we will see the process called osmosis of a red onion, with different material (distilled water, salt water and a microscope).

Objectives:
- To see what happens to the piece of onion when we put distilled water and salt water.

Process:
PHASE 1: NORMAL CELLS/DRY MOUNT 
1. Carefully slice away the colored layer of cells from the red onion. This should only be the thin purple layer. Trim to get a piece about this actual size.
2. Place the thin, purple onion layer on a dry microscope slide shinny side up-do not put on water or cover slip yet.
3. Scan the entire onion tissue on low power to find and center the most purple area and focus. Set the microscope to medium power and focus the view.
4. Take a picture

PHASE 2: SALT WATER ENVIRONMENT/WET MOUNT 
Now that you have observed the layer of normal cells which are the subject of this lab, make a wet mount using 2 or 3 drops of salt water solution on the onion tissue then install cover slip.

5. Watch the cells for approximately 2-3 minutes or longer as you again survey the entire onion tissue on low power. You should see changes within many of the cells intially near the perimeter of the onion tissue. As time passes all or most of the cells shoulb become affected by the salt water. Find some cells that have noticeably been affected and observe them under medium power.

Obervations: We can see the process of plasmolosis 

PHASE 3: DISTILLED WATER ENVIRONMENT/WET MOUNT 

6. After you have colored the diagram correctly above, you need to prepare for phase 3 of this lab by putting the entire salt water wet mount in the dish of tap water to rinse off the salt water from the slide, cover slip and onion tissue layer. Dry the slide and cover-slip then gently dab the onion tissue dry.

7. Make a wet mount of the onion tissue you just rinsed using 2 or 3 drops of distilled water on the onion tissue then install cover slip. Watch the cells for approximately 2-3 minutes or longer as you again survey the entire onion tissue on low power. You should see changes within many of the cells intially near the oerimeter of the onion tissue. As tine passes all or most of the cells should become affected by the distilled water. Find some cells that have noticeably been affected by the distilled water and observe them under medium power.

Observations: The cells become more bigger because they took the water

Questions: 
1. When the salt solution was added to the onion cells, where was the greater concentration (most pure) of water? (inside or outside the cell membrane). How do know this? Explain:
Answer: Inside, because outside is the salt solution.

2. In the winter, grass often dies near the roads that have been covered in salt to remove the ice. Using what you have learned in this experiment, what do you think is the reason the grass dies?
Answer: The cells leaved water.

3. Which kinf of transport does water follow across the membrane?
Answer: Passive (membrane difussion)

ANIMAL CELLS vs PLANT CELLS

Introduction
In this experiment we will se the difference between animal cells and plant cells, using different food (onion)
The Material that we need is: Toothpick, 2 slides, 2 covers slips, distilled water, methylene blue, iodine, onion, glycerine.

Objectives
1. Identify the major components of cells. 
2. Differemtiate between animal and plant cells. 
3. Measure dimensions of the entire cell and nucleus. 

Procedure 
(PLANT CELLS OBSERVATION)

1.  Pour some distilled water into a watch glass. 
2. Peel off the leaf from half a piece of onion and using forceps, pull out a piece of transparent onion peel (epiderms) from the leaf. 
3. Put the epiderms in the watch glass containing distilled water. 
4. Take a few drops of iodine solution (or safranin) in a dropper and transfer into another watch glass. 
5. Using a brush (or a needle), transfer the peel into the watch glass containing the dye. Let this remain in the safranin solution (or iodine) for 30 seconds, so that peel is stained. 
6. Take the peel from the iodine solution and place it in the watcg glass containing distilled water. 
7. Take a few drops of glycerine in a dropper and pour 2 or 3 drops at the center of a dry glass slide. 
8. Using the brush, place the peel onto the slide containing glycerine. 
9. Take a cover slip and place it gently on the peel with the aid of a needle. 
10. Remove the extra glycerine using cellulose paper. 
11. View in the microscope. 

 

RESULTS

 

DNA EXTRACTION

INTRODUCTION: 
Deoxyribonucleic acid (DNA) is a nucleic acid that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses.
Nucleic acids are biopolymers formed by simple units called nucleotides. Each nucleotide is composed of a nitrogen-containing nucleobase (G, T, C, A) as well as a monosaccharide and a phospate group.

OBJECTIVES: 
1. Study DNA structure.
2. Understand the process of extracting DNA from a tissue.

PROCEDURE:
(Put the ethanol in the freezer) 

- Prepare the buffer in a 0'5L beaker: Add 450mL of tap water, 25mL of a dish soap and 7g NaCl. Stir the mixture.

1. Peel the kiwi/banana and chop it to small pieces. Place the pieces of the kiwi in one 600mL beaker and smash with a fork until it becomes a juice puree. 

2- Add 8mL of buffer to the beaker. 

3. Mash the kiwi/banana puree carefully for 1 minute without creating many bubbles. 

4. Filter the mixture: put the funnel on top of the graduated cylinder. Place the cheesecloth on top of the funnel. 

5. Add beaker contain carefully on top of the cheesecloth to fill the graduated cylinder. The juice will drain through the chessecloth but the chucks of kiwi/banana will not pass through into the graduated cylinder. 

6. Add the pineapple juice to the green juice (you will need about 1mL of pineaplle juice to 5mL of the green mixture DNA solution). This step will help us to obtain a purer solution of DNA. Pineapple juice contains an enzyme that breaks down proteins. 

7. Tilt the graduated cylinder and pour in a equal amount of ethanol witg an automatic pipet. Put the ethanol through the sides of the graduated cylinder very carefully. You will need about equal volumes of DNA solution to ethanol. 

8. Place the graduated cylinder so that it is eye level. Using the stirring rod, collect DNA at the boundary of ethanol and kiwi/banana juice. Do not stir the kiwi juice; only stir in the above ethanol layer. 

9. The DNA precipitate looks like long, white and thin fibers. 

10. Gently remove the stirring rod and examine what DNA looks like. 

FINAL RESULT:

This is the final result when que took the DNA and we saw it with the microscope.