Viruses

Question 0

What is the purpose of the envelope?

Answer 0

The envelope is a structure found In many viruses which surrounds the capsid it is made up of a lipid bilayer and often times helps the virus bond to a cell

Question 1

What is a capsid and what is it’s function?

Answer 1

The capsid is a protective protein shell which houses the viruses genetic material. The main functions of the capsid are to protect the viral genetic material from cellular digestion, it has proteins on its surface that allow bonding to host cells. The capsid also contains proteins to allow the virus to break through the host cell membrane

Question 2

What does nucleic acid do?

Answer 2

Nucleic acid functions basically the same way in viruses as it does in multi-celled organisms. But the molecules housing genetic material can range from DNA to RNA with many different stranding patterns

Question 3

What is a tegument?

Answer 3

Also known as the viral matrix the tegument lines the space between the viral envelope and capsid generally teguments are responsible for housing proteins helping viruses evade the immune response as helping with viral cell invasion

Question 4

What are prions

Answer 4

Prions are mis folded proteins which misfold more proteins and degrade cells brain matter etc.

Question 5

Explain the difference between sense and anti sense DNA

Answer 5

The sense strand acts as a coding strand which actually codes for genetic material antisense strand is non coding and acts as a strand running anti to the sense strand

Question 6

Baltimore classification 1

Answer 6

This viral group is comprised of viruses with double stranded DNA and simply hijacks host cells for replication purposes

Question 7

how are viruses important in the evolution of cellular genomes?

Answer 7

viruses are important in the evolution of cellular genomes because when viruses integrate their DNA into a host cell many times the viral DNA gets passed on in humans viral DNA accounts for 1/10 of the genome.

Question 8

why are we unable to develop as many antivirals as we are antibiotics?

Answer 8

since viruses use the host cell for growth and replication it is hard to create drugs which target a virus but not the host cell.

Question 9

what are cloning vectors?

Answer 9

cloning vectors refers to when a virus has its genetic material removed and artificial genes are inserted so when the virus infects a cell the cell starts producing the product of the new gene

Question 10

what are bacteriophages?

Answer 10

viruses that infect bacteria

Question 11

what is host range?

Answer 11

host range refers to the groups of species that can be infected by one strain of virus

Question 12

what are plaques and how are they important in counting viral cells in a culture?

Answer 12

plaques are clear spots in a lawn of cells where the presence of a virus has caused the lysing of the nearby cells

Question 13

what are reading frames

Answer 13

the reading frame refers to what portion of genetic materials read and translated into subsequent proteins because viruses have very small genomes multiple reading frames are used on a very small amount of DNA making up a genome of less than ten genes

Question 14

are large viral genomes possible?

Answer 14

large viral genomes are possible and usually can code for a couple of hundred genes

Question 15

what are viroids?

Answer 15

viroids are like viruses in that they contain small amounts of genetic material which infects and replicates in plants but they lack things like a capsid and other protective layers seen in viruses

Question 16

what are ribozymes?

Answer 16

ribozymes are pieces of RNA that are capable of catalyzing reactions. in medicine they may be useful because they can cleave specific RNA sequences involved in cancer

Question 17

virus capids take two main shapes what are they

Answer 17

icosahedral or filamentous

Question 18

what does an icosahedral capsid look like

Answer 18

an icosahedral capsid has 20 sides and has twenty identical triangular faces with three unique types of axis a five fold a three fold and a two fold

Question 19

how can we observe viruses?

Answer 19

viral particles can be observed by transmission electron microscopy but to see the capsid you need to use digital reconstruction via cryo-em

Question 20

what are spike protiens

Answer 20

spike proteins are proteins which attach the envelope to the capsid.

Question 21

we have the ability to culture bacteriophages why dont we use them as a class of antibiotic especially against antibiotic resistant bacteria

Answer 21

….

Question 22

what is the basic structure of a filamentous virus?

Answer 22

a filamentous virus is composed of capsid monomers which are stacked in a coiled cylinder, a short tail of proteins extend from one side of the capsid which aid in attachment to host cells

Question 23

many bacteriophages are actually very complex true or false?

Answer 23

true: many bacteriophages used the same basic packaging as other viruses but have excess structures that allow them to more easily attach and infect bacterial cells.

Question 24

viruses are not classified by genetic relation due to the high amount of mutation they experience and the fact that many viruses may have arisen from different sources instead we classify them by...

Answer 24

``` genome composition- which refers to how genetic information is packaged capsid symmetry envelope- presence or absence size of virus particle host range ```

Question 25

Baltimore group 2

Answer 25

this class is composed of viruses with a single strand of coding DNA which must first transcribe a complimentary strand using host DNA polymerase the virus can then replicate

Question 26

Baltimore group 3

Answer 26

this group is composed of double stranded RNA viruses these viruses require an RNA dependent RNA polymerase which is a viral protein which allows for the generation of RNA by transcribing from RNA

Question 27

Baltimore group 4

Answer 27

this group consists of sense strand RNA which can code directly for all of the protiens needed for the virus to replicate but must first synthesis an anti-sense strand of RNA in order to replicate

Question 28

Baltimore group 5

Answer 28

this group is composed of viruses which contain anti-sense RNA. these viruses must carry with them transcription factors to help synthesis a sense strand of RNA and then the proteins contained in the virus

Question 29

Baltimore group 6

Answer 29

group 6 is composed of retroviruses these viruses use a protein called reverse transcriptase to turn their RNA genome into DNA which is then integrated into a host's genome

Question 30

Baltimore group 7

Answer 30

pararetroviruses these viruses start out with a DNA genome which is then transcribed into RNA then reverse transcribed (using either a packaged or host cell reverse transcriptase) back into DNA which is integrated into the host genome.

Question 31

how are viruses compared via genetic analysis?

Answer 31

viruses are compared at orthologs or orthologous genes which are genes of common ancestry within two different genomes

Question 32

what is proteomics

Answer 32

proteomics is the comparison of viruses using their proteins rather than their DNA

Question 33

there are four major steps in all viral life cycles what are they?

Answer 33

host recognition- the connection of viruses to an appropriate host cell genome entry- virus must enter the cell and gain access to host cell genome assembly of virons- viral components are expresses and assembled exit and transmission- new viruses must exit the cell and infect new hosts

Question 34

how do viruses recognize their host cells?

Answer 34

viruses recognize their host cells by surface receptors that are already in place on host cells, usually these receptors are actually proteins with important functions that are used as recognized binding sites

Question 35

ebola

Answer 35

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Question 36

hiv

Answer 36

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Question 37

parvovirus

Answer 37

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Question 38

influenza

Answer 38

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Question 39

adenovirus

Answer 39

most commonly used gene therapy virus

Question 40

what is the lytic cycle?

Answer 40

the lytic cycle is when the virus immediately produces as many virus particles as possible and causes cell lysis

Question 41

what is the lysogeny cycle

Answer 41

lysogeny is when the virus integrates into a hosts genome and then replicates along with the cells generally stress on the host cells can cause the virus to enter the lytic cycle

Question 42

what is transduction?

Answer 42

transduction is when a virus as it is leaving a cell grabs little pieces of host genomes and ends up transferring those genes to the next host it comes into contact with

Question 43

how does transduction affect host genomes?

Answer 43

transduction is responsible for a large part of host genome evolution this is one way many different animals incorporate and pass on new genes

Question 44

what is the slow release cycle

Answer 44

the slow release cycle is different from both the lytic and lysogony cycle in this cycle viruses are incorporated into the host genome then viruses are slowly released from the cell and the genetic material is maintained and replicated during cellular division

Question 45

do bacteria have an adaptive defense mechanism?

Answer 45

yes bacteria have developed an adaptive defense mechanism where upon destruction a small piece of viral genetic material found in all viruses called a CRISPR is incorporated into RNA Cas proteins which allow bacterial cells to remember the particular virus

Question 46

what is a major difference between DNA and RNA viruses and how they replicate

Answer 46

RNA viruses can replicate in the cytoplasm without ever interacting with DNA, versus DNA viruses must enter the nucleus of the host cell fro replication to occur

Question 47

how does replication occur for RNA viruses with a sense strand of RNA

Answer 47

viruses with a sense strand of RNA first use a ribosome to translate RNA dependent RNA polymerase which then copies the RNA genome then capsid protiens are translated using host ribosomes and finally virons are assembled in the cytoplasm

Question 48

what are the tree ways plant viruses can infect plants

Answer 48

transmission of viruses through damaged tissues transmission of viruses through animal hosts transmission of viruses though prodgeny

Question 49

once inside a plant how do viruses infect new cells

Answer 49

in order for viral particles to move between cells in a plant they must use the plasmodesmata