How Virus Attaches to a Host Cell

Viruses

Are


NON
–

LIVING!!!

Question

•
WHAT ARE THE 6
CHARACTERISTICS OF ALL LIVING
THINGS?



6 Characteristics

•
Cellular Organization

•
Reproduce

•
Use energy

•
Respond to environment

•
Are composed of specific chemicals (DNA,
proteins…)

•
Grow and develop



Viruses

A virus is
non
-
living

yet has some
characteristics of living things.


•
What do you think are the
characteristics that a virus has in
common with living things?

Why Viruses are NON
-
LIVING…

•
Viruses are
NOT

cells

•
Viruses
DO NOT

use energy to grow and
develop

•
Viruses
Do NOT

respond to their
surroundings

Virus Requirements:

•
NO sign of binary fission

–
(The division of a parent cell to produce 2 new
cells)

•
Have DNA or RNA (never both)

•
Have the ability to take over host cells to make
new viruses

•
Be able to attach to a host

What is a VIRUS?

•
A virus is a microscopic PARTICLE that gets
inside a cell.

•
A virus can also be known as a PARASITE.

•
A PARASITE is something that feeds off
another organism (the HOST)

–
Usually harms the host

–
The host never benefits from a parasite.

Viruses




Are

PARTICLES

PARASITES

MEANS NOT

LIVE IN

CELLS

HOSTS

for viruses are

Smaller Than

Reproduction Requires

Two Basic Parts

•
Outer protein coat

–
Which protects virus


•
Inner core

–
Made of genetic
material

Virus vs. Bacteria

•
Using what you have learned so far…


Compare and contrast viruses and
bacteria.

Virus Acrostic Poem

•
The assigned term or word is written vertically
(VIRUS)

•
Words or concepts related to the term are
written horizontally

•
An illustration (in COLOR)representing the
term or word must follow the poem


Do Now

•
In 20 words or less write a statement about
viruses in comparison to living organisms.


From Coffee Carbon

•
http://learn.genetics.utah.edu/content/begin/
cells/scale/


Basic Shape of Viruses

SPACECRAFT

CYLINDERS

Basic Shapes

SPHERE

CRYSTAL

•
Using what you know and have learned
so far…WHAT IS YOUR DEFINITION OF A
VIRUS?


What is a VIRUS?

•
A virus is a microscopic PARTICLE that gets
inside a cell.

•
A virus can also be known as a PARASITE.

•
A PARASITE is something that feeds off
another organism (the HOST)

–
Usually harms the host

–
The host never benefits from a parasite.

What is a HOST?

•
A host is an organism
from which a parasite
takes food or shelter.

•
Viruses are very
specific for host cells
because of receptor
sited found on host cell
wall or cell membrane.

How do they ATTACH???

•
Viruses are
SPECIFIC….

•
Almost like a KEY
is specific to a
LOCK


*How Virus Attaches to a
Host Cell*

Bacteriophage

Viruses Attack

•
The host cell
membrane has
receptor proteins.


•
The virus particle also
has proteins.


•
The protein coat of
the virus must match
protein receptors of
the host cell.

Classification of Viruses

1.
Shape

2.
Type of Disease Caused

3.
Type of Genetic Material

4.
Life Cycle



Naming Viruses

NOT ALIVE
–

DO NOT USE BINOMIAL
NOMENCLATURE

Instead the name them by…

1.
Name after the disease it causes (Polio)

2.
Organism they infect (Tomato mosaic)

3.
Place it was first found (Ebola virus )

4.
After people (Epstein
–
Barr virus)

Viral Vectors
-

Advantages

•
General advantages of viral vectors:

•
They're very good at targeting and entering
cells.

•
Some viral vectors might be engineered to
target specific types of cells.

•
They can be modified so that they can't
replicate and destroy the cell.


Viral Vector
-

Disadvantages

•
A virus can't "expand" to fit a piece of genetic
material larger than it is naturally built to carry.
Therefore, some genes may be too big to fit into a
certain type of virus.

•
Viruses can cause immune responses in patients,
resulting in two potential outcomes:

–
Patients may get sick.

–
A patient's immunity to a virus may prevent him from
responding to repeated treatments.


Virus as a Vector

•
http://learn.genetics.utah.edu/content/tech/g
enetherapy/gttools/


Exit Questions

1.
In you own words describe the
process of genetic engineering.

2.
Do you think that using a viruses
and bacteria as a vectors are a good
or bad idea? Explain.