Transcript VIRUSES ARE NOT ALIVE BUT AFFECT LIVING THINGS

VIRUSES ARE NOT ALIVE
BUT AFFECT LIVING
THINGS
VIRUSES SHARE SOME
CHARACTERISTICS WITH
LIVING THINGS
• VIRUSES MULTIPLY INSIDE LIVING
CELLS
• VIRUSES MAY HARM HOST CELLS
VIRUSES
• VIRUS means poison; much smaller than
bacteria, can’t even be “filtered” out of a liquid
like bacteria can be.
• Viruses have genetic material inside of a
protective protein coat called a CAPSID.
• They come in many shapes & sizes, but all have a
CAPSID and GENETIC MATERIAL.
• VIRUSES must use a host cell to reproduce (by
making genetic material & capsids).
• Viruses do not grow & don’t respond to changes
in the environment, so they are not living
organisms
Viruses Multiply inside Living Cells
• Viruses use HOST CELLS to make copies of
themselves. A bacteriophage (means bacteria
eater) is used to show the process.
• ATTACHMENT: virus attaches to cell
• INJECTION: injects its DNA inside
• PRODUCTION: uses cell’s machinery to copy
the viral DNA and capsids
• ASSEMBLY: viral DNA forces infected cell to
assemble new viruses
• RELEASE: cell bursts open, releasing 100+ new
viruses to infect other cells.
• Viruses have proteins on surface that look like
proteins the host cell normally needs to fool it &
“dock” onto sites of cell membrane
Viruses May Harm Host Cells
• Virus uses cell’s material, energy , and processes
to reproduce often bursting out & destroying the
host cell. (some just hide in cell or just make 1
virus at a time & not be as harmful)
• About 25 million people died of influenza virus
in outbreak after WWI.
• Plant viruses can stunt growth & kill plants
• Plant, animals, bacteria & all other living things
can be infected by viruses.
• Scientists can use viruses to insert pieces of
genetic material into living cells. (like a marine
organisms DNA into other tissue causing it to
glow so can study it better)