 |
| 400x |
dilluns, 23 de març del 2015
L15. Cells Organelles
 |
| Tomato cromoplast (400x) |
 |
| Chloroplasts of Vallisneria sp |
 |
| Carrot cromoplast (100x) |
 |
| Red cabage (100x) |
 |
| Red cabage cloroplast (400x) |
 |
| Red cabage stoma (1000x) |
dilluns, 9 de març del 2015
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 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.
- 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 |
diumenge, 1 de març del 2015
L12: Animal cells vs. Plant cells
Plant Cells:
Material:
- 2 watch glasses
- slide
- cover slip
- distilled water
- iodine
- onion
- glycerine
Material:
- 2 watch glasses
- slide
- cover slip
- distilled water
- iodine
- onion
- glycerine
dilluns, 16 de febrer del 2015
L11. DNA extraction
Introduction:
Deoxyribonucleic acid (DNA) is a nuclic acid that encodes the genetic instructions used in the development and fuctioning of all known living organsims and many viruses.
Nucleic acids are biopolymers formed by simple units called nucleotids. Each nucleotide is composed of a nitrogen-containing nucleobase (G, T, C, A) as well as a monosaccharide (deoxyribose) and a phosphate group.
Most DNA molecules consist of two strands coiled around each other to form a double helix. The two strands run in opposite directions to each other and are therefore anti-parallel. Moreover the bases of the two opposite strands unit according to base pairing rules : A-T and G-C.
Material:
Deoxyribonucleic acid (DNA) is a nuclic acid that encodes the genetic instructions used in the development and fuctioning of all known living organsims and many viruses.
Nucleic acids are biopolymers formed by simple units called nucleotids. Each nucleotide is composed of a nitrogen-containing nucleobase (G, T, C, A) as well as a monosaccharide (deoxyribose) and a phosphate group.
Most DNA molecules consist of two strands coiled around each other to form a double helix. The two strands run in opposite directions to each other and are therefore anti-parallel. Moreover the bases of the two opposite strands unit according to base pairing rules : A-T and G-C.
Material:
- 1L Erlenmeyer flask.
- 100mL beaker.
- 10mL graduated cylinder.
- Small funnel.
- Glass stirring rod.
- 10mL pipet.
- Knife.
- Safety goggles.
- Cheesecloth.
- Kiwi.
- Pineapple juice (1mL/5mL).
- Distilled water.
- 90% Ethanol ice-cold.
- 7mL DNA buffer.
- 50mL dish soap.
- 15g NaCl.
- 900mL tap water.
Procedure:
Put the ethanol in freezer you will need it really cold later.
Prepare the buffer in a 0,5L beaker: add 450 mL of a tap water, 25 mL of dish soap and 7g NaCl. Stir the mixture.
1- Pell the kiwi 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 mortar.
3- Mash the kiwi puree carefully for 1 minutewithout 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 cheesecloth but the
chucks of kiwi will not pass through into the graduated cylinder.
6- Add the pineaple juice to the green juice (you will need about 1mL of
pineaple juice to 5mL of the green mixture DNA solution). This step will help us to obtain a purer solution DNA. Pineaple juice contains an enzyme that breaks down proteins.
7- Tilt the graduated cylinder and pour in an equal amount of ethanol with
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 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.
Questions:
1- What did the DNA looks like?
The DNA looks like long, small white and thin fibers.
2- Why do you mash the kiwi? Where it is located inside the cells?
Because you want to liberate the DNA that is located inside the nucleus.
Because you want to liberate the DNA that is located inside the nucleus.
3- Explain what is the function of every compund of the buffer (soap
ans salt) The salt breaks the nucleus and the cell and the soap takes
away the proteins.
4- DNA is soluble in water, but not in ethanol. What does this fact
have to do with our method of extraction?
This means that we can only
see the DNA in the part of the ethanol beucause if it touches the water
it will dissolve.
L10. Proteins and evolution
Introduction:
Genes are made of DNA and are inherited from parent to offspring. Soma DNA sequences code form RNA which, in turn, codes for the amino acid sequence of proteins. Cytochrome C is a protein involved in using energy in the cell. Cytochrome C is found in most, if not all, known eukaryotes. Over time, random mutations in the DNA sequence occur. As a result, the amino acid sequence of Cytochrome C also changes. Cells without usable Cytochrome C are unlikely to survive.
Genes are made of DNA and are inherited from parent to offspring. Soma DNA sequences code form RNA which, in turn, codes for the amino acid sequence of proteins. Cytochrome C is a protein involved in using energy in the cell. Cytochrome C is found in most, if not all, known eukaryotes. Over time, random mutations in the DNA sequence occur. As a result, the amino acid sequence of Cytochrome C also changes. Cells without usable Cytochrome C are unlikely to survive.
Cytochrome C is associated with the inter membrane of the mitochondrion. It is a small protein from eucaryote cell.
Procedure and conclusions:
We compare the protein "Cytochrome C":
Mamales: horse, whale and donkey
Birds: chicken and penguin
Reptils: snake
Insect: moth
Fungi: yeast
Plant: wheat
Horse
|
Donkey
|
Whale
|
Chiken
|
Penguin
|
Snake
|
Moth
|
Yeast
|
Wheat
|
|
Horse
|
0
|
||||||||
Donkey
|
0
|
0
|
|||||||
Whale
|
5
|
4
|
0
|
||||||
Chiken
|
11
|
10
|
9
|
0
|
|||||
Penguin
|
13
|
12
|
10
|
3
|
0
|
||||
Snake
|
21
|
29
|
18
|
18
|
19
|
0
|
|||
Moth
|
24
|
23
|
22
|
23
|
23
|
26
|
0
|
||
Yeast
|
40
|
39
|
39
|
40
|
39
|
40
|
46
|
0
|
|
Wheat
|
38
|
37
|
36
|
39
|
39
|
37
|
40
|
43
|
0
|
(from laura's blog)
 |
| (from myriam's blog) |
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