Part II. Practical course of biology

Theme 1. The forms of living organisms. Biology of a cell. The rules for the use of the microscope

Формы живых организмов. Биология клетки. Правила использования микроскопа

The purpose of the study is to understand:

• features of the structure of prokaryotic and eukaryotic cells;
• the basic methods of studying of cells;
• the variety of forms of cells and nucleus;
• substantive provisions and values of the modern cellular theory.

Questions for self-examination:

1)  The cytology as a science, its role in biology;

2)  Cell theory, the basic stages (M. Schleiden, T. Schwann, R. Virchow). Contemporary statements;

3)  Cell as an elementary, genetic, structural and functional biological unit;

4)  Forms of life: cellular and non-cellular;

5)  Differences between prokaryotes and eukaryotes;

6)  Structure of eukaryotic cell;

7)  Differences between animal and plant cells;

8)  Microscope device;

9)  The rules for the use of the microscope;

10)  Procedure of the preparation of temporary slide.

Microscope device. Устройство микроскопа. All parts of the microscope can be divided into three parts: mechanical, lighting and optical.

Optical part includes: eyepiece and objectives.

They have a lens that increase the image.

Figures on an eyepiece and objectives point to how much they increase.

On your microscopes there are two objectives: the Low power and the High power.

The magnification of Low power Objective is 8 or 10.

The magnification of High power Objective is 40.

Lighting part includes a lamp or mirror and a condenser.

Using a mirror, we catch the light beam.

Condenser regulates the intensity of the lighting.

Condenser has a field lens adjustment (diaphragm).

Mechanical part includes:

1)  base;

2)  arm;

3)  stage;

4)  draw tube;

5)  revolving;

6)  coarse focus knob;

7)  fine focus knob.

On the stage the studied slide is placed.

Coarse focus (adjustment) knob changes the distance from the objectives to the slide and is used for finding the image of the object.

Fine focus (adjustment) knob is used for more detailed research of the slide.

Fig. 209. Microscope compound parts: 1 — base; 2 — arm; 3 — draw tube; 4 — stage clips; 5 — opening of the stage; 6 — knobs of the stage; 7 — eyepiece (ocular lens); 8 — revolving nosepiece; 9 — objectives; 10 — coarse (focusing) adjustment knob (macrovint); 11 — fine (focusing) adjustment knob (microvint); 12 — condenser; 13 — condenser adjustment knob; 14 — field lens adjustment (diaphragm); 15 — mirror (or light source)

Work № 1. Microscope device

Работа № 1. Устройство микроскопа

1. Read the text about «Microscope device».

2. Using fig. 209, find all the parts on your microscope.

Please do not twist anything! Please do not touch the lens!

3. Remember the name of every part of the microscope

4. Write down the parts of the microscope in a table 23 and fig. 210.

Table 23. Microscope device

Fig. 210. Microscope details

5. Write down microscope details in the picture (Fig. 210).

Work № 2. Work with microscope. Finding images

Работа № 2. Работа с микроскопом. Нахождение изображения

1. Read and remember the rules of the use of the microscope.

2. Find the image on the slide «Onion epidermis».

Rules for the use of the microscope

1. Set the microscope correctly.

2. The study of any object is started with small increase!

3. Select the low-power objective (small increase). To do this, turn the revolving nosepiece until it clicks into place. The distance from the lens to the object stage should be about one centimeter.

4. Lift the condenser. Open the diaphragm.

5. Look into the eyepiece and rotate the mirror until the field of view will be evenly lit.