The mussels

OBJECTIVE: See and observe the sexual dimorphism of different mussels.

MATERIAL:

• Fresh and closed mussels
• Knife
• Scissors
• Forceps
• Latex gloves
• Dropper
• Distilled water
• Needles
• Spatula
• Microscope
• Slide and corverslip

PROCEDURE: In this case we are going to observe a male mussel.

1. Take a mussel and open it with the help of a knife.
2. Then observe if it's a female of a male. The females are more orange than the males, that are more white.
3. Observe the parts of your mussel, like the gonads, or the foot. 
4. On the gonad we are going to see a white liquid that is the semen of the mussel. 
5. With a spatula take a sample of the semen and put it in a slide with a coverslip and observe it in the microscope. 
6. If the microscope is good we can get to see the sperms.
7. If you want you can cut some part of the mussel and put it in a loupe to observe it.

QUESTIONS:

1. Differences between male and female mussel. The male mussel is more largest than the female that is more ovalated. Also the females are orange and the males are more white.
2. Mark the anatomical parts of the mussel. 
3. Family, class, order and suborder in Latin. Mytilidae, bivalvia, mytiloida, pteriomorphia.
4. Do the gametes move? Why the male mussel have the tail smaller than in human espermatozoides? The gametes do not move and the tail of a male mussel espermatozoides are smaller than in human espermatozoides because it doesn't have to move a lot to fertilize the ovum.
5. Internal or external fertilization? As much as the fertilization and the development of the zygote occurs at the exterior.

Cell mitosis

OBJECTIVE: 

The objective is to see the different phases of the cell mitosis with a rood of an onion.

MATERIAL:

• Beaker
• Slide and cover slide
• Forceps
• Watch glass
• Filter paper
• Lighter
• Bunser burner
• Orcein A
• Orcein B
• Onion 
• Scissors
• Dropper
• Microscope

PROCEDURE:

1. Cut a root of the onion and put it in a watch glass.
2. Add 2ml of Orcein A to the root.
3. Open the bunsen burner and warm it up until we see weak vapors.
4. Then take the root with the forcepsand put it on a slide and add some drops of Orcein B.
5. Put the slide on the filter paper and put the cover slide. With the paper filter wrap the slide and clean out the excess of Orcein B.
6. Put the slide in the microscope and observe it.

RESULTS:

When we watch the sample on the microscope we have to see the phases of mitosis if we have done it well.

Yogurt

OBJECTIVE: The objective is to know how does the Gram stain and also to find bacteria that are called Lactobacillus and Streptococcus, that are G+ and G-

MATERIAL:

• Yogurt
• Ethanol
• Crystal violet
• Distilled water
• A bunsen burner
• 3 beakers
• Dropper
• Lighter
• Slide and cover slide
• Needle
• Lugol
• forceps
• Petri dish
• Microscope

PROCEDURE:

1. Take the needle and warm it up in the bunsen burner, and then, with the cold needle, take a sample of the yogurt
2. Put the sample on a slide and put some drops of distilled water. Also warm it up in the bunsen burner and with the help of a forceps until the water evaporate
3. Add two or three drops of crystal violet in the sample of yogurt and wait for one minute and a half. Then clean the slide with distilled water
4. Add also two or three drops of Lugol to seal the crystal violet and wait for one minute
5. After this minute clean the sample with distilled water to move away the excess of dye.
6. Then add ethanol to take away the dye of the G- and to see the G+

RESULTS:

The G+ are the ones that are dieying with a red colour and the G- are the ones that are transparent.

QUESTIONS:

1.  Explanation of Gran stain

Gram staining involves three processes: 

• staining with a water-soluble dye called crystal violet

• decolorization

• counterstaining

Due to differences in the thickness of a peptidoglycan layer in the cell membrane between Gram positive and Gram negative bacteria.

Gram positive bacteria retain crystal violet stain during the decolorization process, while Gram negative bacteria lose the crystal violet stain and are instead stained by the safranin in the final staining process.