viruses and how they work. what is a virus? a non-living particle – reproduces by using a host...
TRANSCRIPT
What is a virus? A non-living particle – reproduces by using a
host cell
A VERY small particle – 17 to 300 nanometers long (and remember = 1 nm is 1/1 000 000 000 of a meter)
They are a thousand times smaller than a bacteria!
Unlike a cell, they cannot be seen by a light microscope.
What do they look like?
They are of MANY different shapes
They all have a capsid or a protective protein coat
Have a set of genetic instructions DNA or RNA
Some may have a lipid membrane and are called enveloped viruses
What are they missing?
There is an absence of organelles
There are no enzymes (proteins) needed to carry out the life processes
They only have one or two enzymes that decode their genetic information
Blocking these enzymes is effective treatment in a disease like AIDS from the HIV virus
Viral Infections Viruses enter through
openings – nose, mouth, eye etc
Upon entering they will find a host cell to infect the influenza virus attack the lining of the respiratory system while HIV attacks the T-cells of the immune system
Lytic cycle – The basic steps
Attachment to host – proteins to recognize hosts or some have membranes that are dissolved into the host
Genetic material from virus released into the cell – injected if capsid remains on the exterior of the host
Host enzymes are recruited to do the work – making new genetic pieces or protein coats and capsids
Enzymes make new viral parts
Assembly of the new parts to make new virus particles
New particles break FREE – pinch out through the membrane or breaking open the host cell
Inside the cell One virus creates more that lyse
open the cell and new cells are attacked
This loss of host cells inside the respiratory tract allows sinus fluids to flow – the runny nose of the cold!
Viral particles spread to the bloodstream and lungs – resulting in cough and fever
Muscle cells can be attacked and you have the aches of the flu!
The Lysogenic Cycle
Some viruses do NOT reproduce right away
The viral genetic information mixes with the host DNA and can remain dormant for a long period of time, reproducing as part of the host DNA – there are no symptoms of the disease at this time – can last for years – HIV and Chicken Pox
A genetic signal or trigger will initiate the takeover of the viral DNA reproducing the genetic code and capsids and the lytic cycle starts which ends in the release of the new virus particles
Prevention and Treatments
Spread through carrier organisms, infected persons, the air and on surfaces in the environment
To reduce the spread – cover your mouth when you sneeze or cough – wash hands often- avoidance of others body fluids
Taking care in the presence of peoples with weakened immune systems
Medicines do NOT include antibiotics, but immunization is suggested, (vaccines are modified on a regular basis due to mutations)
Taking care of yourself when infected
Using medicines that block the enzymes of the host cells that have been recruited by the virus particle