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    VIRUSES - GR 7 Lesson Notes

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    clairehong08

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    VIRUSES - GR 7 Lesson Notes

    Uploaded by

    clairehong08
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    Original Title

    VIRUSES - Gr 7 Lesson Notes (1)

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    31 views3 pages

    VIRUSES - GR 7 Lesson Notes

    Uploaded by

    clairehong08

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 3

    VIRUSES

    Learning Objectives
    1. Name and describe the characteristics of viruses and how they multiply
    2. Discuss both positive and negative ways that viruses affect living things.

    What Are the Characteristics of Viruses?


     A virus is a tiny, nonliving particle that enters and reproduces inside a living
    cell.
     Viruses are nonliving, have a protein coat that protects an inner core of genetic
    material (DNA or RNA), and cannot reproduce on their own.

    Virus Needs
     Viruses are nonliving because they are not cells, do not use their own energy to
    grow or to respond to their surroundings, cannot make or take in food, and
    cannot produce wastes.
     The organism that a virus enters and multiplies inside of is called a host.
     A host is an organism that provides a source of energy for a virus or another
    organism.
     A virus acts like a parasite.
     A parasite is an organism that lives on or in a host and causes it harm.
     Almost all viruses destroy the cells in which they multiply.
    Virus Shapes
     Viruses can be round, rod-shaped, bricks, threads, bullets, or robots

    Virus Sizes
     Viruses are so small that they are measured in units called nanometers.
     The average virus is quite small when compared with even the smallest cells.

    How Viruses Multiply


     After a virus attaches to a host cell, it enters the cell and takes over many of the
    cell’s functions.
     It instructs the cell to produce the virus’s proteins and genetic material, and they
    assemble into new viruses.

    The Structure of Viruses


     All viruses have a structure featuring two basic parts: an inner core containing
    genetic material and a protective protein coat.
     Each virus contains unique surface proteins, the shape of which allows the virus
    to attach to certain cells in the host.
    How Do Viruses Interact With the Living World?
     Though viruses can cause disease, they can also be used to prevent and treat
    illness.

    Viruses and Disease


     Some viral diseases can pass through the body quickly, whereas others have
    much more serious and lasting effects on the body.
     Viruses also cause diseases in organisms other than humans.
     Dogs and cats, as well as trees, for example, can be infected with viruses.

    Usefulness of Viruses
     Scientists have learned how to take advantage of a virus’s ability to enter a host
    cell.
     In gene therapy, a virus is used to deliver genetic material to cells that need it.
     A vaccine is a substance introduced in the body to help produce chemicals that
    destroy specific viruses.
     Because vaccines are made from dead or weakened viruses, they do not cause
    disease.
     Instead, they activate the body’s natural defenses so that if that virus ever
    invades the body again, it will be destroyed before it can cause disease.

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