"Virus" PPT courseware 4

Description

"Virus" PPT courseware 4

teaching objectives

1. Describe the main characteristics of viruses and the relationship between viruses and human life.

2. Pay attention to the relationship between viruses and other organisms in the biosphere, especially the relationship with humans.

Self-study guidance (1)

Read the first paragraph of P89 and think:

1. Who discovered the virus?

2. Try to describe the discovery process of the virus in your own words.

1. Discovery of viruses

At the end of the 19th century, when Russian scientist Ivanovsky was studying the cause of tobacco mosaic disease, he speculated that the disease was caused by bacteria. He squeezed out the juice from tobacco infected with mosaic disease, filtered it with a bacterial filter to filter out the bacteria, and then used the filtered juice to infect normal tobacco leaves. He found that normal tobacco leaves could still become diseased. This suggested that tobacco mosaic disease was caused by a pathogen smaller than a bacterium, which he called a "filtration virus."

Later, when other scientists studied foot-and-mouth disease in animals, they proved that foot-and-mouth disease was also caused by a "filtration virus."

With the advancement of science, in the early 20th century, scientists first observed tobacco mosaic virus as a rod-shaped particle using an electron microscope.

Self-study guidance (2)

Read textbook P90 and think:

1. What is the type, shape and size of the virus?

2. How do viruses live?

3. What three categories can viruses be divided into based on their hosts?

4. What are the structural characteristics of viruses?

5. How do viruses reproduce?

Type of virus (depending on the virus host)

⑴Animal viruses: viruses that specifically parasitize in human and animal cells, such as influenza viruses;

⑵Plant viruses: viruses that specifically parasitize in plant cells, such as tobacco mosaic virus;

⑶Bacterial viruses: Viruses that specifically parasitize in bacterial cells are also called bacteriophages such as E. coli phages.

How do viruses reproduce?

Viruses can only parasitize in living cells and rely on the genetic information in their own genetic material to use the materials in the cells to create new viruses. This is its way of reproduction.

Once a virus enters a living cell, its genetic material will use intracellular materials to synthesize viral proteins and genetic material within the cell. These proteins and genetic material are then assembled into new viruses. Once the cell is filled with new viruses, the cell It will lyse and release viruses, which can in turn infect other living cells.

In-person testing

1.At the beginning of the 20th century, scientists first observed tobacco mosaic disease using ( )

A. Magnifying glass B. Electron microscope

C. Telescope D. High-power optical microscope

2. What does the structure of a virus consist of? ( )

A. Cell wall, cytoplasm, nucleus

B. Cell membrane, cytoplasm, nucleus

C. Cellulose shell and core composed of genetic material

D. protein shell and core composed of genetic material

3. Which of the following statements about viruses is incorrect ( )

A. Viruses are much smaller than bacteria

B. Viruses come in various shapes, including sphere, rod, tadpole, etc.

C. Viruses have no cellular structure

D. Viruses are harmful to humans

In-person testing

1. Viruses have no cellular structure and are too small to be observed using _______.

2. Viruses cannot _______ life. Can only be parasitic in the _______ of other organisms. According to the different types of parasitic organisms, viruses can usually be divided into _______ viruses, _______ viruses and _______ viruses.

3. The structure of a virus is _______, consisting of a _______ outer shell and an inner _______. Viruses can only parasitize in _______, rely on the genetic information in their own _______ and use materials in cells to create new viruses. When a virus leaves a living cell, it usually becomes a _______ body.

4. There are many types of viruses, which are distributed in _______ and live in _______, causing great harm to humans, animals and plants. On the one hand, humans try to _______ and _______ viral diseases, and on the other hand, _______ viruses benefit humans.

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Update Time: 2024-10-05

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 1 industry PPT template

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