6.2 APBIO Virus

are viruses living? Why or why not

no, they have no cells and can not feed or procreate by themselves (need host)

what is a virus

genetic material enclosed in protection

virus structure

always has capsid that covers viral genetic material/nucleic acid

sometimes has envelope that helps virus be undetected by immune system and is an extra layer of protection of the capside and thus the genetic material

What is the virus capsid

protective protein layer around genetic material in virus

made of capsomere proteins

what is the virus envelope

lipid bilayer envelope made of host cell membrane and both viral and host molecules that aids in infection (can even have glycoproteins/tail things to specific bind to host cell) and protection

what type of genetic material is found in viruses

all; double or single DNA, double or single RNA

host range

# of cells a virus can infect

viruses are…

obligate intercellular parasites; unable to exist without a host

why do viruses need host

for duplication, sustenance, “ill die without u” behavior fr

bacteriophage (phage)

infects bacteria, its glycoprotein/protein tail attaches to the host cell and injects

has two cycles, lytic and/or lysogenic. does one at a time but can switch version

retroviruses

RNA → DNA via reverse transcriptase (enzymes)

bad proofreading so they accumulate mutations easily and thus evolve/differentiate faster

type of provirus

HIV

retrovirus that causes AIDS

double stranded DNA

provirus

The host’s RNA polymerase turns virus DNA → RNA

permanent and integrated into host cell

role of RNA in retrovirus and provirus

function both as mRNA for synthesis of viral proteins and as genomes for new viruses released from the cell