X Answer the questions:

1. What kind of microscope is used the most common in microbiology?

2. What kind of objective lenses do you know?

3. How is calculated the total magnification of an object?

4. What does light microscope use for to examine specimens?

5. For what is immersion oil used?

11-12 Practical lesson

Rules of reading: The letter combinations er, ir, yr, ur, or, ar

Word formation: suffix of nouns – ion, -tion

Text: The prokaryotic cell

Assignments to do:

I Remember:

a) Letter combination ar is pronounced as [a:], e.g.: far

Letter combinations er, ir, yr, ur are pronounced as [ә:], e.g.: her, sir

Letter combination or is pronounced as [o:], e.g.: for

1. Suffixes –ic, -al form adjectives from the nouns:

person – personal

history – historical

base – basic

Remember!!!

So is used to express the result of the statement before.

Because expresses the reason or cause of something.

Cause -----------------------------------------------Result

it started to rain, so we stopped playing tennis.

Result------------------------------------------------Cause

We stopped playing tennis because it started to rain.

II Read the words paying attention to the pronunciation:

Large, term, firm, colour, girl, sister, mark, fork, fur, her, similar, their, factor, first, burn, war.

III Read and translate the following words:

Central, experimental, academic, electric, prokaryotic, practical, monumental, historical, bacterial, social.

IV Read and translate the text about prokaryotic cell The prokaryotic cell

The members of the prokaryotic world make up a vast heterogeneous group of very small unicellular organisms. Prokaryotes include bacteria and archaea. The majority of prokaryotes, including the photosynthesizing cyanobacteria, are bacteria. Although bacteria and archaea look similar, their chemical composition is different. The thousands of species of bacteria are differentiated by many factors, including morphology (shape), chemical composition (often detected by staining reactions), nutritional requirements, biochemical activities, and sources of energy (sunlight or chemicals). It is estimated that 99% of the bacteria in nature exist in biofilms.

The chief distinguishing characteristics of prokaryotes (from the Greek words meaning prenucleus) are as follows:

1. Their DNA is not enclosed within a membrane and is usually a singular circularly arranged chromosome. (Some bacteria, such as Vibrio cholerae, have two chromosomes, and some bacteria have a linearly arranged chromosome.)

2. Their DNA is not associated with histones (special chromosomal proteins found in eukaryotes); other proteins are associated with the DNA.

3. They lack membrane-enclosed organelles.

4. Their cell walls almost always contain the complex polysaccharide peptidoglycan.

5. They usually divide by binary fission. During this process, the DNA is copied, and the cell splits into two cells. Binary fission involves fewer structures and processes than eukaryotic cell division.