Viral Infection
Video Clips on Viral Infection- WHAT’S HAPPENING: Note down things that you see the virus doing
that is helping it to reproduce
METHODS OF VIRAL INFECTION
Viruses have two ways of infecting the host cell:
-______________________
-______________________
Lytic Infection
Lytic Cycle Stages
1. Lytic virus injects its nucleic acid into the host
2. ____________________________________
3. host cell starts replicating the viruses proteins and nucleic acids
4. _________________________________ ____________________________and releases new virus particles
5. particles can attack other host cells
Lytic Infection causes host cell to be “lysed” and destroyed.
Lysogenic Infection
Lysogenic cycle stages
1. Lysogenic virus injects its nucleic acid into a host cell
2. __________________________ __________________________→ provirus
3. Every time host cell reproduces, the provirus is replicated along with it → ________________
_______________________________________
The lysogenic cycle can take place for many years
At any time the provirus can be activated and enter a lytic cycle and _____________________
Viruses and Diseases
Viruses cause human diseases such as ________ ____________________________________
Viruses attack and destroy certain cells in the body → _______________________________
The best way to prevent against viral diseases is to prevent infection through vaccination.
What is a vaccine?
_______________________________________ _______________________________________
When injected into the body, _______________ _______________________________________
For vaccines to be most effective it must be used before an infection begins.
Vaccines are used for the prevention of ______ ______________________________________
Vaccines _______________________________
Retroviruses
Viruses that contain _______________ ________________________________
When retroviruses infect a cell _________ ___________________________________
Called retroviruses because their genetic information is ______________________.
Copied from ____________________instead of DNA to RNA
Retroviruses are responsible for some types of cancer and HIV
Retroviruses and cancer
Retroviruses can cause some cancers
Retroviruses that convert, or transform, normal cells → tumor viruses
These viruses carry genes that disrupt the normal controls over cell growth and division
HIV
_______________________________
Causes AIDS
Is a retrovirus
Infects__________________________
Causes the development of AIDS because more and more white blood cells are infected
Virus can go into lytic cycle and begin killing the persons white blood cells
Plant Viruses
Tobacco Mosaic Virus was the first virus to be identified
______________________________________
Lytic and Lysogenic Cycles
Bacteriophages must invade bacteria cells to reproduce. A host cell provides the necessary
substances for the production of new bacteriophages. The host cell is destroyed as the new viruses
rupture the host’s membrane and leave the cell.
Study the diagram below showing two cycles of viral reproduction and then complete the following
paragraph
.
Part 1 begins the (1)________________________________ cycle. In this process a
(2)_____________________, known as a bacteriaphage, attaches to the wall of the host cell. The
viral tail matches up to a complementary (3) ___________________________ site along the
bacterial wall. After (4)_________________________ released by the virus weaken the wall, the
hollow tail is forced through the host and viral (5) _______________ passes into the cell, enters
the chromosome, and stimulates the production of messenger RNA. As the messenger RNA migrates
into the (6)_______________________, it carries the genetic information for the production of
viral nucleic acid and the viral (7) ________________ ______________, which are assembled into
(8)_____________________. These new viruses release enzymes that weaken the cell wall and the
host cell ruptures, or (9) ______________, releasing the viruses. Part 5 shows a portion of the (10)
_____________________ cycle. During this process, the viral nucleic acid (11)___
______________________ along with the (12) ____________ __________ of the host. As this
host cell goes through _______ ____________ the viral DNA is also replicated. Eventually this cell
will go through the lytic cycle and the new viral parts will be __________________ and
______________. Just like with before eventually this cell will become too large and ________
releasing the viruses to repeat the process.
Word Bank:
DNA, cytoplasm, lytic, assembled, enzymes, is integrated, lysis, produced, virus, protein capsids, receptor,
Viruses, lysogenic, genetic information, cellular division, burst