Bellwork: February 11
Copy the question and the answer
Both euglena and cyanobacteria are
photosynthetic unicellular organisms found in
pond water. The feature that distinguishes
euglena from cyanobacteria is the —
A ability to maintain homeostasis
B presence of ribosomes
C ability to reproduce
D presence of a nuclear membrane
CO:
I will describe viral reproduction.
LO:
I will write notes and talk about
the steps in viral reproduction. I
will build a virus.
Science Fact of the Day:
Corneas are the only tissues that don't require blood.
OVERVIEW
Quick Write:
• Are viruses alive?
• Explain why or why not.
When a virus invades…
A living thing
that provides
a source of
energy for a
virus or an
organism
VIRUS
A tiny, nonliving structure that
invades and then multiplies inside
of a cell.
A virus that immediately goes into action.
It begins to take over cell functions and
produce the virus’s proteins and genetic
material. These parts then assemble into
new viruses. The viruses multiply like a
copy machine left on. When it is full the
cell bursts open – releases the new viruses
and dies.
Organisms
that live on
or near a
host and
cause harm.
Some viruses hide for a while and become
part of the cell’s genetic material. It may stay
inactive and “hidden” for years. Then under
certain conditions it becomes active and acts
like an active virus. Ex – cold sores
Lytic Cycle
•Active viruses enter cells and
immediately begin to multiply, leading
to the quick death of the invaded cells.
•Steps to the lytic cycle:
1. Attach to cell
2. Inject DNA/RNA
3. Produce (replicate) virus parts
4. Assemble new virons
5. Release viruses to infect other cells
- Viruses
Lytic Cycle
Lysogenic Cycle
• Hidden viruses “hide” for a while inside host cells
before becoming active
1.
2.
3.
4.
5.
6.
Steps to the Lysogenic Cycle:
Attach to cell
Inject DNA/RNA
Integrate DNA/RNA into cell
Wait
Remove DNA/RNA
Become active (lytic cycle)
- Viruses
Lysogenic Cycle
Rally Robin: Cycle Steps
• Get into partners—decide who is
partner A and who is partner B.
–Partner A: Describe the steps for the
Lytic cycle.
–Partner B: Draw each step.
• After a few minutes, we will switch
to the Lysogenic Cycle and you will
switch roles.
Lytic Cycle
Lysogenic Cycle
Could viruses be helpful?
- Since viruses can transport DNA and RNA into
cells, scientists are exploring Gene Therapy
- In Gene Therapy, viral genetic material is
replaced with new DNA
- In time, this could be used to cure genetic
diseases. Currently we have no cure for
these types of illnesses
You decide…Lytic or Lysogenic
Dengue Fever
For spread of infection Thursday..
• Could we be the Last of Us?