BIOL 1202 - CH 19

virus

infectious particle considiting of genes packaged in a protein coat

simpler in structure than prokaryotic cells

cannon reproduce or carry out metabolism outside of a cell

viral genome

double/single-stranded DNA

double/single-stranded RNA

single linear or circular molecules

capsid

protein shell surrounding the viral genome

may be referred to as helical or icosahedral viruses

viral envelope

surroudning the capsid of influenzas viruses and many other viruses found in animals

contains a combination of viral and host cell molecules

bacteriophage

viruses that infect bacteria

elongated capsid head that encloses their DNA

protein tail piece attaches the phage to the host and inject the phage DNA inside

hemagglutinin

for the flu H1N1, what does "H" stand for?

neuraminidase

for the flu H1N1, what does "N" stand for?

lytic cycle

phage replication cycle that culiminates the deaht of the host cell

produces new phage and lyses the host's cell wall, releasing the progeny viruses

produces a virulent phage

lysogenic cycle

replicates the phage genome without destroying the host

viral DNA is incorporated int othe host cell's chromosomes

phage that use both lytic and lysogenic and lytic cycle are called temperate phages

restriction enzymes

cleave DNA molecules at specific base sequence

CRISPR-Cas system

both bacteria and archae can also protect themselves from viral infection with this

A cell is transfected with an enzyme complex contain: guide molecule, healthy DNA copy, and DNA-cutting enzyme

A specially designed synthetic guide molecule finds the target DNA molecule

An enzyme cuts off the target DNA strand

The defective DNA strand is replaced with a healthy copy

smallpox virus

double stranded DNA (dsDNA) disease

B19 parvovirus

single-stranded DNA (ssDNA) disease

zika virus

single-stranded RNA (ssRNA) serves as mRNA disease

ebola virus

ssRNA; serve as template for mRNA synthesis

fusion and entry inhibitors

prevent HIV entry

non-nucleoside reverse transcriptase inhibitors

prevent reverse transcriptase replication

nucleoside/nucleotide analogues

prevent HIV replication

integrase inhibitors

prevent HIV integration

protease inhibitors

prevent HIV assembly

vaccine

harmless derivative of pathogenic microbes that stimulates the immune system to mount defense agains the harmful pathogen

epidemic

widespread occurrence of an infectious disease in a community at particular time

ex: flu-like illness caused by influenza in Mexico and US in 2009

pandemic

global epidemic

ex: black death, Spanish flu, HIV/AIDS

endemic

disease that exists permanently in a particular region or population

ex: malaria in African and chicken pox in US

sporadic

disease that sene only occasionally usually without geographical concentration

ex: tentanus, rabies, and typhoid fever in US

plant viruses

known and cause spots on leaves and fruits, stunted growth, and damaged flowers or roots

have an RNA genome

ex: immature tomato and tobacco mosaic virus

vertical transmission

inheriting the virus from a parent

horizontal transmission

entering through damaged cell walls

prion

an infectious protein that appear to cause degenerative brain diseases in animals

are misfold proteins -> can be transmitted in food and are virtually indestructible

causes scarpies in sheep, mad cow disease, and Creutzfeldt-Jakob disease

tobacco mosaic virus

stunts the growth of tobacco plants that give their leaves a mosaic coloration

In the late 1800s researcher4s hypothesized that small bacteria caused it

in 1935 confirms that the infection agent did not share features with bacteria by crystallizing the infectious particle

capsomeres

capsids are built from protein subunits called

ghost

empty bacteriophage is called

general process of how a virus infect

1. entry and uncoating

2. replication

3. transcription and manufacture of capsid proteins

4. self-assembly of new virus particles and their exit from the cell

prophage

the integrated viral DNA

Every time the host divides, it copies the phage DNA and passes the copies to the daughter cell

environmental signal can trigger the virus genome to exit the bacterial chromosome and switch to the lytic mode

cold sore

eruption around the mouth or lips; herpes simplex virus Type 1

typically treated with antiviral medication Valacyclovir

ebola, chikungunya, zika virus

examples of emerging viruses

R0

represent the number of people that a single infected person can be expected to transmit the disease to

ex: high R0 value: measles

low R0 value: influenza