Версия сайта для людей с нарушением зрения
только для медицинских специалистов

Консультант врача

Электронная медицинская библиотека

Раздел 5 / 41
Страница 1 / 6

Lesson 4. COMPLEX (CONJUGATED) PROTEINS: HEMOPROTEINS AND NUCLEOPROTEINS. NUCLEIC ACIDS

Questions to study.

1. Chromoproteins: their structure and representatives.

2. Hemoproteins: their definition, structure, significance, and representatives.

3. Hemoglobin, its structure. Its role in oxygen transport in human body. Cooperative binding of oxygen by hemoglobin. Regulation of oxygen binding by hemoglobin. Derivatives of hemoglobin. Hemoglobin switching during ontogenesis. Hemoglobinopathy.

4. Nucleoproteins: their definition, classification and significance.

5. Nucleic acids (DNA and RNA): their definition, structure, and functions. Nucleotides and nucleosides. Free mononucleotides and their derivatives: their structure, representatives and significance.

Assignment for self-instruction

#

Task

Guidelines for performing the task

1

2

3

1

Study the structure of hemoglobin

1. Describe the chemical structure of heme.

2. How is heme joined to globin in hemoglobin?

3. Make a schematic drawing of the quaternary structure of hemoglobin

2

Study the structure and features of hemoglobin derivatives

1. Write down the scheme of formation of oxyHb, carboxyHb, carbHb.

2. What is first aid upon carbon monoxide poisoning?

3. What is metHb? List chemical compounds that initiate methemoglobinemia

Ending of the table

1

2

3

3

Study the structure of nitrogenous bases, nucleo-sides and nucleotides. How is the polynucleotide chain of DNA and RNA formed?

1. Write down the DNA fragment which consists of dT-dA-dG.

2. Write down the RNA fragment which consists of C-U-A

4

Study the secondary structure of DNA and levels of DNA packing in nucleo-proteins

1. Draw the double helix of DNA molecule and characterize it.

2. How are major and minor grooves of DNA molecule formed? Explain the complementarity between adenine and thymine, guanine and cytosine.

3. What does nucleosome mean? Describe the levels of DNA folding.

4. Characterize the biological role of histones in nucleoproteins

5

Study the structure of various RNA types and the structure of ribonucleo-proteins

1. Characterize the secondary and tertiary levels of folding of RNA molecule.

2. What are the features of ribosomal RNA? Make a schematic drawing of ribosome and characterize the structure of its subparticles.

3. Make a schematic drawing of tRNA. List the features of its structure. Describe the biological role of tRNA

Library-research paper

1. Thalassemia.

2. Myoglobin: its structure and functions.

LABORATORY WORK

1. Qualitative responses to hemoglobin

Revealing of the heme molecule in hemoglobin is carried out using benzi-dine and guaiac test.

1.1. Benzidine test

The test is based on the ability of hemoglobin to catalyze oxidation of ben-zidine by hydrogen peroxide in diphenylquinone diimine. Then the latter it is condensed by a molecule of unoxidized benzidine to yield a blue-green colored product.

Procedure

Add 1 ml of blood diluted 5000 times to one test tube, and add 1 ml of distilled water to the other one. Place both test tubes for a few minutes in a boiling water bath. After cooling, add 5 drops of freshly prepared 3% alcoholic solution of benzidine and 3% hydrogen peroxide solution to both tubes. Characteristic blue-green coloration appears in the test tube with diluted blood.

1.2. Guaiac test

Hydrogen peroxide oxidizes α-guaiaconic acid in the presence of heme (hemoglobin) yielding blue color.

Для продолжения работы требуется вход / регистрация