- •Viruses and subviruses
- •1. Make sure you know the following words:
- •2. Read and translate the text.
- •Viruses and subviruses
- •Viruses
- •Subviruses
- •Comrehension check
- •1. Choose the right variant for the multiple-choice statements.
- •2. Questions to think about.
- •3. Think of 5-7 statements that would contradict the contents of the text. Language focus
- •2. Form the derivatives of the words given in the table (where possible):
- •3. Define the following terms:
- •4. Match the first half of a sentence in column a with the appropriate second half in column b:
- •5. Put the parts of the sentences in the right order:
- •1. Prepare a dialogue with your partner discussing:
- •2. Sum up what you have learned about viruses and subviruses and prepare a report about them. Unit 2 monera
- •1. Make sure you know the following words:
- •2. Read and translate the text.
- •1. Choose the right variant for the multiple-choice statements.
- •6. Put the parts of the sentences in the right order:
- •1. Prepare a dialogue with your partner discussing:
- •Unit 3 protista
- •1. Make sure you know the following words:
- •2. Read and translate the text.
- •1. Choose the right variant for the multiple-choice statements.
- •Define the following terms:
- •4. Match the first half of a sentence in column a with the appropriate second half in column b:
- •5. Put the parts of the sentences in the right order:
- •1. Prepare dialogues discussing: a) general information about the kingdom Protista; b) primitive protists; c) true algae; d) unicellular algae.
- •2. Prepare a report on the topic under discussion. Unit 4 fungi
- •1. Make sure you know the following words and word combinations:
- •1. Choose the right variant for the multiple-choice statements.
- •2. Questions to think about.
- •3. Think of 5-7 statements that would contradict the contents of the text.
- •4. Put the parts of the sentences in the right order:
- •1. Name and describe: a) the major groups of fungi; b) the ways of fungal nutrition.
- •2. Prepare a report on the topic under discussion.
- •Plant kingdom: plantae
- •Make sure you know the following words and word combinations:
- •Read and translate the text.
- •Choose the right variant for the multiple-choice statements.
- •Give detailed answers to the questions below:
- •Think of 5-7 statements that would contradict the contents of the text.
- •Put the parts of the sentences in the right order:
- •1. Explain the terms: Chlorophyta, Phaeophyta, Rhodophyta.
- •Prepare a dialogue with your partner discussing reproductive structures of algae and higher plants.
- •Prepare a report: How did embryophyte plants inhabit terrestrial environments? unit 6 bryophyta. Vascular plants. Psilophyta. Lycophyta
- •2. Read and translate the text.
- •Choose the right variant for the multiple-choice statements.
- •Give detailed answers to the questions below:
- •Think of 5-7 statements that would contradict the contents of the text.
- •Put the parts of the sentences in the right order:
- •Name the new terms learned by you from the text.
- •Prepare a dialogue with your partner discussing club mosses.
- •Write an essay on the topic Bryophyta. Unit 7 sphenophyta. Pterophyta. Gymnosperms. Cycadophyta. Ginkgophyta
- •2. Read and translate the text.
- •1. Choose the right variant for the multiple-choice statements.
- •Give detailed answers to the questions below:
- •Think of 5-7 statements that would contradict the contents of the text.
- •Put the parts of the sentences in the right order:
- •Describe the genus Ginkgo.
- •Prepare a dialogue with your partner discussing cycadophytes.
- •Prepare a report about pterophytes. Unit 8 coniferophyta: conifers. Anthophyta / angiosperms: flowering plants
- •1. Make sure you know the following words:
- •2. Read and translate the text.
- •1. Choose the right variant for the multiple-choice statements.
- •2. Ask questions revealing the main points of the text.
- •3. Think of 5-7 statements that would contradict the contents of the text.
- •5. Put the parts of the sentences in the right order:
- •1. Describe: a) how angiosperms are pollinated; b) the life cycle of conifers.
- •2. Prepare a dialogue with your partner discussing:
- •3. Write essays on the topics: a) conifers; b) flowering plants. Unit 9 typical flower
- •1. Make sure you know the following words:
- •2. Read and translate the text.
- •Say whether the following statements are true or false:
- •Give detailed answers to the questions below:
- •Put the parts of the sentences in the right order:
- •Divide the text into parts and give a title to each of them.
- •Prepare a report on the topic under discussion. Contents
Subviruses
The smallest infectious agents known to researchers are termed subviral infectious agents, or subviruses. Scientists have identified at least six different strains: satellite viruses, virinos, viroids, virusoids, virogenes, and prions.
Members of one of the better understood strains, prions, range in size from considerably smaller than viruses, sometimes 100 times smaller, to almost as large as mitochondria and bacteria. Prions have been found to cause certain diseases and are implicated as the cause of others. Included in this list of diseases that prions seem to promote are scrapies and several similar degenerative brain diseases.
It has been theorized that prions may be radically different from any other known self-replicating entities. There is no evidence that prions contain any nucleic acids, DNA and/or RNA; instead, they appear to be little more than dots of protein. Even if they were found to contain nucleic acids, prions are so small that there is little chance they contain a nucleic acid any longer than 50 nucleotides. This is not large enough to encode a protein containing more than about 12 amino acids.
Despite indications to the contrary, it has even been suggested that prions may actually be conventional viruses, but this is quite unlikely. It appears equally unlikely that they will be found to represent a new category of protoorganismal material that reproduces in living cells, employing a technique that has yet to be elucidated. It has even been suggested that they may reproduce using a technique similar to that employed by viruses, without being viruses.
Some researchers have suggested that the mode of prion reproduction might involve fracture and continued growth, which would explain their small and uncertain molecular weights, their rod-like appearance, their varying lengths, and the unpredictability of which amino acid occurs terminally. The most recent work has shown that prions may be proteins produced somewhat abnormally by infected genes that somehow go awry.
Among the other subviruses are the viroids, minute rings of RNA that infect certain plants. Virusoids appear to be loops of RNA that occur inside regular viruses. Virinos, like viruses, need an outer coat of protein, which they are unable to make on their own, but which they induce host cells to manufacture. Virogenes are otherwise normal genes that generate infectious particles under certain circumstances. Satellite viruses are tiny pieces of RNA that make full-size viruses work for them. These tiny nucleic acids multiply inside viruses that are inside cells.
Comrehension check
1. Choose the right variant for the multiple-choice statements.
Viruses contain
nucleic acids b. a protein coat
DNA or RNA d. viral capsid
all of the above.
Viruses do not
Metabolize b. generate their own energy
c. replicate (or duplicate, or reproduce) without injecting cells
d. all of the above e. none of the above.
The information contained in the viral DNA or RNA is
inserted into its host’s cellular machinery
contained in the viral nucleic acids that are inserted into their host’s DNA
used to direct the host to produce more viruses
all of the above e. none of the above.
Each of the many different types of viruses “know” which cells to attack by identifying ______________ on the potential host’s outer _____________ .
receptor sites, protein coat b. nucleic acids, viral capsid
c. receptacles, bacteriophages d. all of the above
e. none of the above.
Viruses that attack only bacteria are known as _______________ .
DNA viruses b. RNA viruses
c. retroviruses d. bacteriophages
e. all of the above.
Some viruses infect a host cell by
attaching to the host’s protein coat while injecting the viral DNA or RNA into the host
entering the host intact
injecting viral genetic information into a host’s cells
all of the above e. none of the above.
It is possible that viruses may be moving genetic material from
plants to animals b. animals to plants
c. plants to plants d. animals to animals
all of the above.
Viruses may prove, in some cases, to be the simplest of
all simbionts b. all parasites
c. all living things d. all of the above
none of the above.
Prions have been said to be
the smallest infectious agents known
the largest infectious agents known
100 times smaller than viruses to almost as large as mitochondria and bacteria
the cause of certain diseases e. a, c, and d.
Prions
have been found to contain nucleic acids
have not been found to contain nucleic acids
are viruses d. are not viruses
b and d.
Recent work has shown that prions may be
proteins produced somewhat abnormally by “infected” genes that somehow go awry
bacteria c. viruses
protists e. mitochondria.