Activitat enzimàtica de la catalasa en diferents teixits animals i vegetals

Introducció:

En aquesta pràctica volem valorar l'activitat enzimàtica de la Catalasa en diferents teixits animals i vegetals. Dividirem la pràctica en dues parts: en la primera observarem la diferència d'activitat de la catalasa en diferents teixits animals i vegetals (patata, pastanaga, tomàquet, fetge i cor de pollastre) i en la segona part veurem la influència de determinats factors en l'activitat enzimàtica en el teixit de fetge. 

La catalasa és un enzim present en els peroxisomes de les cèl·lules animals i vegetals que s'encarrega d'eliminar l'aigua oxigenada que es forma en algunes reaccions del metabolisme. La reaccció química és la següent: 

2H₂O₂ -→ 2H₂O + O₂ 

Material: 

• Patata
• Pastanaga 
• Tomàquet
• Fetge
• Cor
• Tubs d'assaig
• Gradeta
• Termòmetre
• Bec de bunsen
• Vidre de Rellotge 
• Tisores
• Bisturí 
• Pinces
• Ganivet 

Part 1: 

Procediment

        ●   Tallarem un tros que faci 1 cm3 de:  patata, pastanga, tomàquet, fetge i cor.

• Pesarem els trossots que gem tallat: Patata: 0,7g, Tomàquet: 0,9g, Pastanaga: 0,9g, Fetge: 0,7g, Cor: 1,00g 
• Ho possarem en cinc tubs (un per a cada teixit) amb 5mL d'aigua destil·lada i 2mL d'aigua oxigenada cada un. 
• Marcarem l'alçada que assoleixen les bombolles en cada tub i ho mesurarem en mm. 

Resultats:

Preguntes: 

Quines són la variable dependent i independent? 

     

- L'alçada de les bombolles és la variable dependent i els diferents te teixits que valorem és la variable independent.

Quin problema és vol investigar?

- Quin teixit presenta més activitat de la catalasa? 

Explicació dels resultats: 

- La catalasa tindrà una activitat enzimàtica més elevada en els teixits animals.

Part 2: 

Procediment: 

• Agafarem 5 tubs d'assaigs i els hi aplicarem els següents procediments: 

Tub 1: Fetge+5mL aigua destil·lada+2mL aigua oxigenada 

Tub 2: Fetge+5mL aigua destil·lada+2mL aigua oxigenada+10mL d'HCl al 10%

Tub 3: Fetge+5mL aigua destil·lada+2mL aigua oxigenada+ 

Tub 4: Fetge congelat+5mL aigua destil·lada+2mL aigua oxigenada 

Tub 5: Fetge+5mL aigua destil·lada+2mL aigua oxigenada 

       

     •   Després mesurarem l'alçada de les bombolles en mm. 

Resultats:

Preguntes:

Quines són la variable dependent i independent? 

     

- L'alçada de les bombolles és la variable dependent i els diferents te teixits que valorem és la variable independent.

Quin problema és vol investigar?

- Com afecten diferents factors en l'activitat de la catalasa?

Explicació dels resultats:

- El tros de fetge que te més activitat és el del tub número 5, el que ha estat submergit en la dissolució saturada de NaCl. A continució el que observem és què el tub número 1 que es troba a temperatura ambient també te una alta activitat. 

Quina és la funció de la catalasa en els teixits animals i vegetals? On es troba aquest enzim? 

- Aquest enzim es troba als peroxisomes i la seva funció és catalitzar la descomposició del peroxid d'hidrogen (H₂O₂₎ en oxigen (O₂₎ i aigua (H₂O).

Per què quan ens fem una ferida ens posem aigua oxigenada? 

- Per evitar possibles infeccions. 

L18. Mitosis in an onion root

Introduction: 

We did an experiment about the observation of mythosis in an onion root. Mitosis is the process in which a eukaryotic cell nucleus splits in two, followed by division of the parent cell into two daughter cells. 

Objectives: 

- View the different stages of a mitosis in the microscope. 

Materials: 

-Onion
-Orceine A and B 
-Dropper
-Watch glass
-Beaker
-Forceps
-Bunsen burner
-Lighter 

-Microscope
Procedure: 

1. A week ago we left an onion in a beaker with some water, (only the tip of the onion touched it) so its roots will grow so we can see the process of mitosis.
2. To start our experiment we took the onion and cut the tip of a root and put it in the watch glass.
3. Then with the dropper we took the orceine A and put some drops on the root and we took the watch glass with the wooden forceps and put it on the bunsen burner so the orceine and the root would heat. Some acid fumes began to evaporate. We had to be careful to not to burn the root so the watch glass could not be too hot, we should be able to touch it with our hand!!
4. After that we took the root with the forceps and put it on a slide and added a couple of drops of orceine B, we waited a couple of minutes.
5. Then with the scalpel we cut 3mm leaving the tip, and always knowing where the tip is. 
6. Finally we added a coverslip and used the squash method so we could observe the cells on the microscope.

Results:

Anaphase

Metaphase

Telophase and prophase

L17. The chloroplast and the photosynthesis

Introduction:

We're going to investigate the photosynthesis in an algae. During the photosynthesis, plants and algae produce oxygen.

In this experiment we want to observe how light intensity affects the rate at which photosynthesis occurs and the rate of oxygen production.

Objetives: 

- Relate the light intensity with the photosynthesis process.
- Measure the rate of photosyntesis.
- Identify the products of the process and the variables that can affect it.

Materials: 

- Algae (Elodea)
- 600 ml beaker
- Test tube
- Funnel
- Tap water 
- Light source
- Metric ruler

Procedure: 

1. First we assigned the different distances to do the experiment and compare the results to each group.
2. We took the 600 ml beaker and placed 7 g of an algae under a clear funnel inside the beaker. The funnel was raised off the bottom on pieces of blue-tack to allow unhampered diffusion of CO2 to Elodea. 
3. We didn't have sodium bicarbonate so we filled the beaker with tap water, the algae and the funnel should be completely under the water.
4. Then we filled a test tube with tap water and placed the thumb over the end of the test tube. We turned the test tube upside down taking care that no air enters and no water comes out and we put this test tube over the end of the funnel (the skinny part)
5. We marked the level of the water on the surface of the test tube with a marker pen.
6. Each group placed the preapartion close to a light source, each group placed the preparation in a different distance 5, 10, 20 and 25 cm, and one with no light source.
7. We also measured the temperature.
8. Finally we left this preparation for and hour and a half. After this time we measured the difference of gas accumulation on the top of the test tube. 

Distance: 5cm

Questions: 

1- Identify the dependent and the independent variable of this experiment.
Dependent: gas production, Independent: distance (intensity of the light)
  
2-Using the data from your results prepare a graph and describe what happened to the amount of gas in the test tube.

Names	Distance	Gas Production	Temperature
Laura i Andrea	25 cm	0,5 cm	22,7 º C
Edu i Ignacio	0 cm	0 cm	21,5º C
Inés i Maria	20 cm	0,3 cm	22,5º C
Myriam i Paula	5 cm	0,5 cm	26,5º C
Liza i Anna	10 cm	0,4 cm	24º C

Myriam and I had 5 cm distance and our water level decreased 0,5 mm in an hour and a half. 

If you have a little distance, the light intensity is higher and the phtoshyntethic rate will be higher too.

We controled the temperature and the algae quantity because this could have and influence on the result. Also, we think that Laura's and Andrea's result is incorrect because the distance is higher so the water level decrease should be lower than the other. Maybe they measured it incorrectly.

3-How much gas was producted in the test tube after one hour? And an hour and a half?
Results in the graphic 

4- Write the photosynthesis equation. Explain each part of the equation. Which subtances are produced by photosynthesis. Which gas is produced that we need in order to live? 

From Laura's blog

Substances produce by photosyntesis; 

Gas is produced that we need in order to live: Oxygen

L16. Life in a drop of water

400x 

 Eucariotic unicelular flagelate

L15. Cells Organelles

Tomato cromoplast (400x) 

Chloroplasts of Vallisneria sp

Carrot cromoplast (100x)

 

Red cabage (100x)

Red cabage cloroplast  (400x)

Red cabage stoma (1000x)

L14: Gram staining

Introduction: 

Gram staining is a method of differentiating bacterial species into two large groups:  gram postive and gram negative.

This differentiation is based by the chemical and physical properties of their cell walls by detecting a peptidoglycan, which is present in a thick layer in gram-positive bacteria.

The result is:

Gram-negative: stain pink or reddish color
Gram-positive: stain purple color

Objectives:

- Differentiate yogurt bacteria
- Relate the stanning procedure with the structure of the cells.

Materials:

- Toothpick
- Slide
- Cover Slip
- Tongs
- Needle
- Gram stain: crystal violet, iodine and safranin.
- Decolorize reagent: ethanol 96%
- Microscope
- Yogurt

Procedure:

- Prepare a heat-fixed sample of the bacteria to be stained.
- Cover the smear with crystal violet for an exposure of 1 min.
- Rinse with destilled water.
- Apply iodine solution for 1 min.
- Rinse the sample with distilled water.
- Decolarize using ethanol. Drop by drop until the purple stops flowing, "Wash immediately with distilled water"
- Cover the sample with the safranin stain for an exposure time of 45 seconds.
- Rinse the sample with tap water.
- Gently dry the slide with paper (only the under part of the slide)

Results:

	GRAM +	GRAM -
Crystal Violet (color?)	PURPLE	PURPLE
Iodine (changes?)	YES	YES
Ethanol (decolorize?)	NO	YES
Safranin (color?)	NO	REDDISH

400x 

400x

L13: Epidermis cells

Objective:

- Identify the shape of epidermis cells
- Identify and explore the parts of a stoma
- Mesure dimensions of the entire cell and the stoma

Material:

- Slide
- Cover Slip
- Distilled water
- 10% salt water
- The kit:  scissors, needle, forceps
- Leek

Procedure:

plant cells observation: 

1- cute the stalk of the leek.
2- In the place of the cut, pull out transparent part of the epidermis using forceps.
3- Using needle, place the peel onto the slide containinga drop of tap water.
4- Take a cover slip and place it gently on the peel with the aid of needle.
5- View it in the microscope.
6. Describe the change in the shape of the cells.

salt treatement:
1- Prepare a 10% of salt solution.
2- Put the salt with a dropper on the left part of the slide (touch the cover slip)
3- Place a piece of cellulose paper in the opposite part of the cover slip, and let the dissolution to go through your sample.

leek with distilled water

leek with the salt treatement