Viruses Flashcards
what are viruses? (characteristics)
-viruses are non living
-lack cellular structure (cytoplasm,organelles,membranes
-do not carry out cellular process (growth, reproduction, respiration)
-must be inside a host (living organism) to reproduce
what is the structure of viruses:
strands of DNA or RNA surrounded by a capsid
Mobile genes that paralyze cells
What does the capsid structure of virus do
a protein coat that protects viruses from host cell enzymes
How can viruses be classified
-diseases they cause
- size and shape
-nucleus acid shape
What are viruses that infect bacteria called
bacteriaphages
define the Viruses shape polyhedral:
20sides
small crystals
define the Virus shape alien shape
polyhedral head attached to protein tail and tail fibers
name all 4 virus shapes
polyhedral
cylindrical
alien shape
spherical
Explain RNA VIRUSES
-70% of all viruses
-more error during reproduction
-higher mutation rates
explain DNA VIRUSES
- need helper viruses for replication
-less errors during reproduction
-lower mutation rates
What do retroviruses do:
alternate between the lyric and lysogenic cycle
What does HIV contain and what does that thing cause ?
contains reverse transcriptase (an enzyme) that cause the host cell to transcribe viral RNA TO DNA
which cycle is more damaging?
Lytic cycle because host cell dies
Why are viruses important?
-responsible for many human diseases and can spread
-can cause epidemic
-some can increase cancer risk
-kill crops
What do vaccines do?
train our bodies to defend against viruses
