L17. CELL ORGANELLES

L17. Cell organelles

 

Tomato chromoplasts

4 x 10 = 40x

Tomato chromoplasts 40 x 10 = 400x

Potato amyloplasts 
 stained with lugol

10 x 40 = 400x

Potato amyloplasts 
 stained with lugol

10 x 100 = 1000x

chromoplast red cabbage

15 x 10 = 150x

chromoplast red cabbage

15 x 40 = 600x

stoma of a red cabbage

15 x 40 = 600x

L16. LIFE IN A DROP OF WATER

L16. LIFE IN A DROP OF WATER

In this picture we see a unicellular eukaryotic organism protozou flagel that moves through the water.

They move very quickly until light microscope makes them go slower and photographs i could make videos.

Thanks to its movement causes undulations in the water getting nutrients carried to the mouth.

In this video we can see a small flagel that moves across the surface and a body that moves up and down.

L15. GRAM STAINING

L15. Gram staining

1. Introduction

Gram staining is a method of differentiating bacterial spieces into two large groups, gram positive and gram negarive. This differentation is based by the chemical and physical properties the their cell walls by detecting a peptidoglycan, which is present in a thick layer in gram -  positive bacteria.

Gram - negative: color pink
Gram - positive: color purple

2. Material

• 1 slide
• 1 cover slip
• Tongs
• Needle
• Gram stain
• Decolorize reagent : 96% ethanol
• Microscope
• Yogurt

3. Objectives

• Differentiate yogurt bacteria.
• Relate the staining procedure with the structure of the cells.

4. Procedure

First of all, prepare a heat-fixed sample of the bacteria to be stained and cover the smear with crystal violet for an exposure of 1 min.

After, rinse with distilled water and apply iodine solution for 1 min and again, rinse the sample with distilled water.

Decolorize using ethanol. Drop by drop until the purpule stops flowing. Wash immediately with disitilled water.

Cover the sample  with the safranin stain for an exposure time of 45 seconds and rinse the shample with distilled water.

Finally, gently dry the slide with paper.

L14. EPIDERMIS CELLS

L14. Epidermis cells

1. Material

• 1 slide
• 1 cover slip
• Distilled water
• 10% salt water
• Scissors
• Needle

2. Objectives

• Identify the shape of epidermis cells
• Identify and explore the parts of stoma
• Measure dimensions of the entire cell and the stoma

3. Procedure

PLANTS CELLS OBSERVATION:

First of all cut the stalk of the leek and in the place of the cut, pull out the transparent part of the epidermis using forceps.

After, using the brush, place the peel onto the slide containing a drop of the water and take a cover slip and place it gently on the peel with the aid of a needle.
View it in the microscope.

After, describe the change in the shape of the cells and finally, draw a diagram with the part of a stome.

SALT TREATMENT:

First of all, prepare a 10% of salt solution and put the salt with a dropper on the left part of the slide.

Then, place a piece of cellulose paper in the opposite part of the cover slip, and let the dissolution to go through your sample.

4. Questions

1. What is the major function of a cell membrane?

2. What is the major function of the cell wall?

3. How does salt affect the cells shape? And the stomes?

L13. ANIMAL CELLS vs PLANT CELLS

L13. Animal cells vs Plant cells

1. Objectives

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

2. Material

• Forceps
• Dropper
• Needle
• 2 watch glass
• Toothpick
• 2 slides
• 2 cover slips
• Distilled water
• Methylene blue
• Iodine
• Onion
• Glycerine

3. Procedure

Plant cells

First of all pour some distilled water into a watch glass and peel off the leaf from half a piece of onion and using forceps, pull out a piece of transparent onion peel from the leaf.

After put the epidermis in the watch glass containing distilled water and take a few drops of safranin solution  in a dropper and transfer into another watch glass.

Using a bursh or a needle, transfer the peel into the watch glass containing the dye. let this remain in the safranin solution for 30 seconds, so that the peel is stained.

Take a peel from the safranin solution and place it in the watch glass containing distilled water and take a few drops of glycerine in a dropper and pour 2-3 drops at the center of a dry glass slide.

Using a brush, place the peel onto the slide containing glycerine and take a cover slip and place it gently on the peel with the aid of a needle.

Remove  the extra glycerine using a cellulose paper.

And finally, view it in the microscope.

Animal cells

Fist of all, gently scrape the inner side of the cheek using a toothpick, which will collect some cheek cells and place the cells on a glass slide that has water on it.

Mix the water and the cheek cells using a needle and spread them.

After, dry the sample under the light to fix the sample on the slide and take a few drops of methylene blue solution using a dropper and add this to the mixture on the slide.

After 2-3 minutes remove any excess water and stain from the slide using cellulose paper and take clean cover slip and lower it carefully on the mixture with the aid of a needle.

Using a top of the needle, press the cover slip gently to spread the epithelial cells.

Finally, remove any extra liquid around the cover slip using cellulose paper.

4. Augments

1. Cell - 5,5 cm = 55000um

NA = 40x · 10x = 400

400 = 55000/MR  ---- MR = 137,5um

2. Nucleous - 0,7 cm = 7000um

400 = 7000/MR ---- MR = 17,5um