Experimental principles for the detection of carbohydrates, fats, and proteins in biological tissues

The sample reacts with the reagent to produce a visible substance.

Glucose, fructose, film reagent, brick-red precipitate.

Iodine, blue. Sudan 3, Sudan 4, red or orange, alcohol lamp.

Biuret reagent, purple.

The sample reacts with the reagent, resulting in a noticeable color change.

Glucose, fructose, film reagent, brick-red precipitate.

Iodine blue (amylose is blue when iodine is present, and amylopectin is purplish red when iodine) Sudan 3 Sudan 4 Red or orange alcohol lamp.

Doubleclacladamide reagent purple.

Identification principle of reducing sugar: there are many types of soluble sugars that are commonly found in biological tissues, including glucose, fructose, maltose and sucrose. The first three sugars contain free, reducing hemiacetal hydroxyl groups in their molecules, so they are called reducing sugars; Sucrose has no free hemiacetal hydroxyl group in its molecule, so it is called non-reducing sugar and is not reducible.

The Filin reagent can only identify reducing sugars, which are able to form a brick-red precipitate with reducing sugars (actually Cu2O) and glucose is oxidized to gluconic acid under heated conditions.

Identification and principle of protein: When identifying whether protein is contained in biological tissues, biuret reagent is commonly used. In alkaline solution (NaOH), biuret can react with copper ions to form a purple or purplish-red complex, and this reaction is called biuret reaction.

Since protein molecules contain many peptide bonds that are structurally similar to biuret, proteins can all react with the biuret reagent to identify the presence of proteins.

Specific experimental operations, precautions.

Specific experimental operations, precautions.

Precautions: Detection of soluble reducing sugars:

1. Plant tissues with high sugar content and white or near-white color should be used in the selection of materials.

2. Feilin reagent is unstable, generally prepared into liquid A (Naoh: G ml) and liquid B (CuSO4: G ml) for storage, when using the two solutions must be mixed evenly before use, do not add to the tissue sample solution for detection.

Fat detection: 1. The slices should be as thin as possible;

2. After dyeing, be sure to wash off the floating color with 50% alcohol solution;

3. When observing, find the thinnest place, preferably only 1 or 2 layers of cells.

Detection of proteins:

1. When using egg protein, it must be diluted, if the dilution is not enough, it will be cemented on the inner wall of the test tube after the reaction with the double urea reagent, so that the reaction is not complete, and the test tube is not easy to clean;

2. When using the biuret reagent, a should be added first to create an alkaline environment, and then b

Analysis: A. Although the composition of the film reagent is the same as that of the biuret reagent, the concentration, usage and dosage are different, such as the B solution of the film reagent (and the B solution of the biuret reagent (the concentration is different, so A is wrong.)

b. There are two methods given in the fat identification textbook: macroscopic detection of fat in peanut seed cells, grinding to obtain sample solution, and then adding Sudan trian, after staining, direct observation can be done, no need to use a microscope. And the second method must be fat. B false.

d. Identification of protein by diurea, no need for water bath heating, D wrong correct answer C

Notes:

Detection of soluble reducing sugars:

1. The selection of materials should be made of plant tissues with high sugar content, white color or nearly white 2. Filin reagent is unstable, and is generally prepared into liquid A (Naoh: G ml) and liquid B (CuSO4: G ml) for preservation.

Fat detection: 1. The slices should be as thin as possible;

2. After dyeing, be sure to wash off the floating color with 50% alcohol solution;

3. When observing, find the thinnest place, preferably only 1 or 2 layers of cells.

Detection of proteins:

1. When using egg protein, it must be diluted, if the dilution is not enough, it will be cemented on the inner wall of the test tube after the reaction with the double urea reagent, so that the reaction is not complete, and the test tube is not easy to clean;

2. When using the biuret reagent, a should be added first to create an alkaline environment, and then b

Specific experimental operations, precautions.

Experimental principle.

The molecules of glucose, fructose, and maltose contain reducing groups (free aldehyde groups or free ketone groups), so they are called reducing sugars. Sucrose, on the other hand, is a non-reducing sugar and is not reducible. Soluble reducing sugars interact with Filin reagent to produce brick-red precipitates.

The Filin reagent is actually an alkaline solution of Cu2+, which can oxidize sugars with free aldehyde groups or free ketone groups, and Cu2+ is reduced to a brick-red precipitate protocol.

1) Add 2 ml of tissue fluid to the tube.

2) Add 1 ml of Filin reagent to the tube (ready to use) 3) Place the tube in a large beaker filled with warm water at 50-65 degrees and heat for two minutes.

Reducing sugar-filin reagent - brown - brick red.

Objective: To detect the presence of sugars, fats, and proteins in biological tissues.

Experimental principle: sugars, fats, and proteins change color when exposed to specific solutions.

Procedure: Prepare a sufficient amount of biological tissue sample solution.

Experiment 1 (sugars).

1) Inject 2ml of tissue sample solution into the test tube.

2) Inject 1ml of Feilin reagent into the test tube (mix the same amount of liquid A and B before injecting) (3) Put the test tube in a large beaker filled with 50-65 degrees of warm water and heat it for about 2minObserve the phenomenon after a while.

Experiment 2 (fat).

1) Inject 2ml of tissue sample solution into the test tube.

2) Add 3 drops of Sudan's solution to the tube.

3) Observe the phenomenon after a period of time.

Experiment 3 (Protein).

1) Inject 2ml of tissue sample solution into the test tube.

2) Inject 1ml of biuret reagent A into the test tubeShake well.

3) Inject 4 drops of biuret reagent B into the test tube. Shake well.

4) Observe the phenomenon after a period of time.

Experimental Phenomenon: Experiment 1The solution in the tube forms a brick-red precipitate.

Experiment 2The solution in the tube is stained red.

Experiment 3The test tube produces a purple reaction.

Conclusion: Experiment 1 contains sugars in the solution to be tested.

Experiment 2 The solution to be tested contains fat.

Experiment 3 The solution to be tested contains proteins.

The above is the report of the whole experiment, written by myself, I hope to give a hard share.

1.In the experiment of detecting reducing sugars, fats and proteins in biological tissues, the requirements for experimental materials: the selected tissue should contain the substance, and the content should be high, the color of the tissue should be clearly contrasted with the reaction results, and the material with a large tissue block should be selected for the fat identification test.

2.The freshly prepared Filin reagent is dark blue.

You have too many questions! Ask the teacher directly! He answers in person, it's better to think about the problem yourself!

For example, if you know that Filin is made of copper sulfate and sodium hydroxide, you're still asking what color it is, of course, copper sulfate. Blue: Think a lot!

1.The corresponding substance is rich in content and light in color.

2 light blue, the color of copper sulphate.

3. There is a problem with the experimental operation.

45. Adjust the object image to the field of view**, do not move the coarse quasi-focal spiral.

6 possible in objective lenses and reflectors.

7. Easy to observe.

8. If several layers are not visible clearly under the microscope.

10 Tumble dry to keep the cells close to the slide to prevent drift during hydrolysis. Wash off the hydrochloric acid to facilitate staining.

4.Prepare with NaOH solution, CuSO4 solution and glucose solution with Filin reagent prepared in a 50-60 water bath that has been heated or the hot water has cooled.

9.Eukaryotic cell DNA is mainly distributed in the nucleus and RNA is mainly distributed in the cytoplasm.

10(1) Fix the cells in position.

2) Prevent the neutralization of hydrochloric acid with basic chromosomes and affect the staining effect.

9.Fixed cells 10Prevent the neutralization of hydrochloric acid with alkaline dyes and affect the dyeing effect.

Uh-uh, uh-uh, I really don't know anything about high school.

Let me answer your question 3! The classmate dripped in too much Sultan III, so that the orange color could not be revealed, so it was always red! That's why the teacher told us not to drip too much Sultan III – I'm Xiu Quandi

Nima's class is not listening, such a basic question can be asked!