What are the characteristics of virus
- obligate intercellular parasites (require loving hosts cells to multiply)
- are very small and are genetic simplicity
- contain either DNA or RNA (one or the other never both)
- no ribosomes
- No ATP- generating mechanism
- replication involves disassembly and reassembly
- has a host range ( can infect only specific types of cells in a limited set of species)
- are very small in size
How are viruses catagorized
They determined by the host attachment sites and cellular factors
What is the basic viral core structure
- contain either DNA or RNA
- is either single or double stranded
- is a continuous or segmented molecule
What is the external coating in the basic viral structure
- has a capsid
- some contains envelopes and others do not
- some contain spikes
On a virus cells what is the capsid
A feature on the external structure that a protein coat made of capsomers
What is the function of the envelope on the outside of the virus external coatings
They are a coating on the outside of some virus’s
- ones that do not have this feature are considered naked viruses
What are the functions of spikes on the external coating of the virus structures
They are projections from outer surfaces that allows for determination for which tissues to infect (the spikes allows the the cell to be accepted by the tissues)
What is the lyric cycle process
- Phage binds to the bacterium
- The phage then puts its DNA into the host cell
- The host DNA is digested
- Phage DNA replicates
- The host cell transcribes and translates the phage DNA -and produces phage proteins
- Assembly of new phages is complete and lysis is caused by a encoded enzyme
- The new phages are then released to start the cycle again
What is the process of the lysogenic cycle
- Phage bonds to the bacterium
- The phage DNA enter the host cell 3. The phage DNA integrates into the bacterial chromosome and becomes a prophage
- The prophage is then replicated as part of the bacterial chromosome and continues to go through cell divisions
- The prophage may separate from the chromosome and the cell will go through the lyric cycle
What is the result of the lyric cycle
-The phage causes lysis and death to the host cell
- produces the production of new phages
What is the result of the lysogenic cycle
- The phage DNA is incorporated into the host DNA or will cause the cell to enter the lyric cycle instead
- ## this cycle only happens with temperate phage only
How is there defense againest phages
- receptor modification: changes so the same phage can not keep binding
(This can be done by sugars changing on the outside of the receptors) - denfense mechanisms
What’s is a epidemic
Are seasonal infections outbreaks and can only happen within in certain environments
What is a pandemic
When multiple places across the world can be infected at the same time
What type of virus is influenza
It is a DNA virus
What is the structure of the influenza virus
- chromosomes are segmented and are usually found in 8 different chromosomes strands
- has different external proteins (h proteins and N proteins)
What is the importance of the H proteins on the influenza virus
Is important for attaching to the host cell
What is the importance of the N proteins
Important for exiting the host cell
What is the lifecycle of the influenza virus
- The virus lands on the outside of the host cell where the H proteins are used to be picked up
- They unpack their DNA
- They use the host cell to replicate the DNA
- They then reform and exit the host cell using the N proteins
- Multiple influenza cells are now created
What is antigenic drift
Are a result of a minor mutations to the N or H mutations which leads to a gradual change
What is the result of a antigenic drift
This point mutations result in epidemics
What are antigenic shifts
This process causes a reassortment of genes
- this is the result of chromosomes from two different cells mixing
What is the result of the antigenic shifts
They cause pandemics and usually only occur in influenza type A
( occurs when two different virus infect the same host and there DNA is mixed together when reforming and a new type is created)
What type of virus is HIV
This virus type is a retrovirus that is RNA based
