MB ch 6 viruses

True or False

Viruses contain DNA and RNA.

False

What is bacteriophage

viruses infect bacteria

Whats the term to make new viruses

lytic cycle (lysis-cell death, make new cells)

What is the best phage virus community in human body?

gut virome

What is lytic cycle?

release is a result of cell lysis induced by viral enzymes and accumulation of viruses

what is the first step of lytic cycle/gut virome?

**binding of virus to specific molecules on the host cell**

what is the second step of lytic cycle/gut virome?

**penetration genome enters host cell**

describe virus multiplication 3 step

synthesis of viral proteins and nucleic acids

describe virus multiplication 2 step

entry of viral nucleocapsid

describe virus multiplication 5 step

release of progeny virions

virus meaning in latin

poison

give an example of a virus that has envelope

Lyssavirus - rabies (rabies are given by saliva of an animal)

what kind of viruses has so many enzymes that seems to be evolved from degenerate cells

large asymmetrical viruses

describe the layers of poxviruses

genome has many layers, a core envelope is studded with spike proteins, an outer membrane

large number of accessory proteins that is NEEDED early in viral infection.

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describe influenza viruses

they are RNA viruses that lack capsid symmetry

instead, the RNA segments are coated with nucleocapsid proteins

does influenza virus have RNA or DNA

RNA

what are the names of two influenza virus spikes

neuraminidase (releases mature virions from the host cell)

hemagglutinin (they bind virions to red blood cells and cause cells to clump together which is known as a process of hemagglutination).

why viral envelopes are useful and what are they mostly found in

\-used to identify cells

\-involved in viral attachment to host cell

\-may have enzymatic activity

\-its mostly found in animal viruses

\-it could stimulate the immune system

what does the naked nucleocapsid not have

spike and envelope

why the animal viruses requires or necessary to have viral envelope

the two reasons are indispensable: protection & attachment

what does the viral envelope cause to viruses

the viral envelope makes viruses pleomorphic

spikes are also known as

peplomers

what does envelope proteins consist of mostly

glycoproteins (proteins that have carbs attached to them)

what is involved with virion attachment to the host cell surface

spikes

what type of virus shape does adenovirus-272-causes diarrhea and respiratory infections

icosahedral capsid

What type of virus shape does poliovirus-32-causes diarrhea or paralysis?

icosahedral capsid

what are largest animal virus and what is the shape of it

poxviruses (that is the animal virus) and complex

Name the shapes of virus

**helical capsid** (short and rigid, or long and filamentous)

* protects the viral genetic material and aids in transfer between host cells
* length of capsid is a function of nucleic acid
* the structure of it is that its repeating molecules that looks like crystalline
* Hep A, Polio, Flu, __TMV__

**icosahedral capsid** (spherical, 20 flat triangles)

* symmetric polygons
* knob shaped units, can vary in numbers and arrangement of promoter
* Poliovirus-32-causes diarrhea or paralysis
* adenovirus - 272- causes diarrhea and respiratory infections

**complex** (vary in shape)

* large bacteriophages - binal symmetry meaning the head and tail segments each are symmetric
* asymmetric: poxviruses - largest animal virus

is virus DNA or RNA protected unlike bacteria

the viral envelope protects it which is protein casing

Are viruses able to metabolize or reproduce on their own

they need a host to do that, specifically hosts ribosomes and enzymes and other crucial cellular components

bacteriophage means

a virus that infects bacteria

what is a helical caspid

its a flexible helix of capsomers that form cylindrical nucleocapsid

capsid + nucleic acid=

=nucelocapsid

whats the function of capsid

to protect the any chemicals or enzymes

define virion

complete infectious viral particle which is the DNA or RNA of a virus that is protected by capsid - capsomers

what do animal viruses must involve for insertion of spike proteins?

secretory pathway

rER→Golgi complex → plasma membrane

describe virus multiplication 4 step

self assembly of virions(assembly is complicated)

describe virus multiplication 1 step

the virus particle comes in contact with host cell - attachment of virion to host cell

What are the five steps of virus multiplication

attachment, entry and uncoating, synthesis, assembly, virion release

Which of the following is a protein molecule, while others are viruses.

\-poxvirus 250nm

\-herpes simplex 150nm

\-rabies 125 nm

\-HIV 110nm

\-Influenza 100nm

\-adenovirus 75nm

\-hemoglobin molecule 15nm

\-T2 bacteriophage 65nm

\-poliomyelitis 30nm

\-yellow fewer 22nm

hemoglobin molecule

infectious agents are:

not dead cells or alive, active or inactive, (extracellular or intracellular) come in contact with host cell, wear mask to protect against infection.

Why is the. Tulip Breaking News important

because it destroyed the Dutch economy, “bitcoin of the 1600s”, wealthy merchants put humble tulip worth 1636 tulip bulb 150$=25,000$ in todays currency. **the virus made tulips more valuable**

virus damaged the colorful tulips pigmentation, economic was brought down,

tulips are originally from Kazakhstan, bulbs (stem, reshesh) were worth far more than bloomed flowers

what is the third step of lytic cycle/gut virome?

**uncoating - the viral nucleic acid is released from the capsid**

what is the fourth step of lytic cycle/gut virome?

**synthesis - the viral components are produced**

what is the fifth step of lytic cycle/gut virome?

**assembly - new viral particles are constructed**

what is the sixth step of lytic cycle/gut virome?

assembled viruses are released by budding (exocytosis) or cell lysis,

how specific is adsorption? can there be more than one receptor

receptors are proteins that are important to normal cellular function and there may be more than one receptor

DdDPs funtion

to replicate DNA

Which best describes prion?

1\.Parasite that depends on helper non-cellular organism for replication

2\. Naked RNA infectious agent

3\. Encapsidated infectious agent that replicates only inside living cells

4\. Non-nucleic acid containing infectious agent

4

Which best describes viroid?

1\.Parasite that depends on helper non-cellular organism for replication

2\. Naked RNA infectious agent

3\. Encapsidated infectious agent that replicates only inside living cells

4\. Non-nucleic acid containing infectious agent

2

Which best describes virusoid?

1\.Parasite that depends on helper non-cellular organism for replication

2\. Naked RNA infectious agent

3\. Encapsidated infectious agent that replicates only inside living cells

4\. Non-nucleic acid containing infectious agent

1

Which best describes virus?

1\.Parasite that depends on helper non-cellular organism for replication

2\. Naked RNA infectious agent

3\. Encapsidated infectious agent that replicates only inside living cells

4\. Non-nucleic acid containing infectious agent

3

DdRPs function:

to transcribe RNA (remember R one is rna so it transcribes the DNA)

Intestinal lumen contains

bacteria and phages

Does the virus kill the host when it synthesizes and make replication of its genome

no because it benefits using the, lysogeny, although phage genes in bacterial chromosomes could cause pathology like HPV

Does animal virus have enveloped or naked nucleocapsid virus?

enveloped

which part of the body would hepatitis B infect

host range:human liver cells

what tissue does HIV affect

host range: CD4 and CCR5 proteins on WBC

what receptors does covid-19 affect

ACE2

what does the virus genome do upon entry

it alters the genetic expression of the host and instructs it to synthesize the building blocks for new viruses

How many human proteins does HIV depends on to complete its cycle

250 human proteins

how do non enveloped viruses lyse the host cell of bacteria,

bacteriophage

holin: create holes in E.coli plasma membrane, enabling T4 lysozyme to move from the cytoplasm to the peptidoglycan

lysozyme: an enzyme that attacks peptidoglycan in host cell wall

how do non enveloped viruses lyse the host cell of eukaryotes

viral proteins may attack cell wall or membrane

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host cell damage or cytopathic effects:

a. shutdown of normal metabolic and genetic machinery

b. destruction of plasma membrane

c. toxicity or viral components

d. release of lysosomes

e. all of the above

E.

describe what are some cytopathic effects

virus induced damage to cells, changes it shape and size, cell lysis, alters DNA, transform cells into cancerous cells, inclusion bodies, cells fuse to form multinucleate cells (syncytia, I think multiple nucleus)

what is the meaning of cytopathic cells

what happens to cell when the virus gets in

which of the following is a step found in animal virus multiplication but not in bacteriophage replication?

A. Adsorption

B. Penetration

C. Assembly

D. Uncoating

E. Release

D.

what is the structure of archaea cell envelope

a monolayer membrane with ether linked lipids and proteinaceous S layer

how does enveloped viruses leave the host cell, host cell:release virions

by **budding** - exocytosis which is when nucleocapsid binds to membrane which pinches off and sheds the virus **gradually**, cell is not immediately destroyed

\-plasmic membrane, Golgi, nucleus, ER

could take few hours

host cell accrues (build up, accumulate) damage

most envelopes arise from plasma membrane

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What are the stages for viral synthesis (gene replication)

early: host control

middle:genome replication

late:viral components synthesized, and virions assembled

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where would the site of synthesis (replication and protein production) would take place if the virus is RNA?

must bring in enzymes/proteins necessary to complete synthesis

where would the site of synthesis (replication and protein production) would take place if the virus is DNA? (dsDNA typical flow)

generally replicated and assembled in the nucleus

negative sense

RNA must be converted into positive sense message,

what are the medical importances of viruses

\-viruses are the most common cause of acute infections

\-several billion viral infections per year

\-some viruses have high mortality rates (N1H1, HIV, AIDS, etc)

\-possible connections of viruses to chronic afflictions of unknown cause (schizophrenia, chronic fatigue syndrome, multiple sclerosis)

\-viruses are major participants in the earths ecosystem

\-COVID-19 rates has decreased, increased in jan 2021 and jan 2022

epstein-Barr virus

Burkitts lymphoma

papillomavirus

cervical cancer

what is transformed cells

they have increased rate of growth, alternations in chromosomes, and the capacity to divide for indefinite time periods resulting in tumors

mechanism of oncogenesis include:

a. insertion of an oncogene into the host genome

b. providing strong regulatory sequences

c. insertion of viral genome knocks out **tumor suppressor genes**

d. expression of viral proteins that interfere with host cell cycle regulation

e. all of the above

E.

Which of the following is true about viruses. Multiple answers

a. Made up of only proteins

b. mainly cause neurodegenerative diseases

c. an infective agent thats able to multiply only within the living cells of host

d. It is made up of nucleic acid molecule covered by a protein coat called nucleocapsid

e. can cause a wide variety of infections

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C, D, E

Which of the following is true about prions? Multiple answers

A. a very simple particle that can infect other living cells

B. less complex even than a virus

C. made up of only proteins

D. its an infective agent that has nucleic acid and a protein coat

E. its an infectious protein that lack nucleic acid

F. mainly cause neurodegenerative diseases.

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A. A, B, C, E

B. A, B, C, F

C. B, C, E, F

D. B, C, D, F

E. B, C, A, F

C.

why viruses in ecology is important

a. viruses are important members of aquatic world.

b. move organic matter from particulate to dissolved

c. important in evolution

d. transfers genes between cells at 20 billion/sec

e. driving bacterial and algal mortality and evolution at the nanoscale, to influencing global-scale biogeochemical cycles and ocean productivity

f. all of the above

F. all of the above

state the two theories regarding viruses

\-cells that may have regressed (fall off) to a highly parasitic existence inside other cells

\-may have originated from loose strands. of genetic material released by cells (early evolutionary state)

What type of cells does virus infects?

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bacteria, algae, fungi, protozoa, plants, and animals

where do viruses acquire their envelope lipids and carbs

from their host

what is viruses envelope proteins coded by

viral genes

many human cancers are caused by

a. unhealthy diet

b. healthy family genes

c. sweets and sugar

d. oncogenic virus

D. because oncogenic viruses **transform** the host cell to become cancerous

virus - response in animal cell

1\.smallpox virus

2\.herpes simplex

3\.adenovirus

4\.poliovirus

5\.reovirus

6\.influenza virus

7\.rabies virus

8\.measles virus

1. cells round up; inclusions appear in cytoplasm
2. cells fuse to form multi-nucleated syncytia; nuclear inclusions

3. clumping of cells; nuclear inclusions


4. cell lysis; no inclusions.
5. cell enlargement; vacuoles and inclusions in cytoplasm
6. cells round up; no inclusions
7. no change in cell shape; cytoplasmic inclusions (negri bodies.
8. syncytial form (multinucleate)

Which is smaller viruses or viroids or prions

smallest to greatest

prions-viroids-virus

true or false

viruses can be extracellular or intracellular

true

positive sense

RNA contains message for translation, viral + mRNA is translated to viral protein

where do RNA viruses generally replicated and assembled

in the cytoplasm

where is viruses or viral replication complex present

in the cytoplasm

describe the synthesis: viral genome part

genomes can be segmented or circular (ex:influenza vs.HepBV), there is overlapping transcription, no metabolic enzymes, number of genes vary (ex: flu - 10 genes, vaccine virus - 250 genes), length of nucleic acid also vary.

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For host cell regulation, synthesis of capsid, genetic material, and packing of virions

during synthesis is the virus ever DNA and RNA

its either dna or rna but never both

in 1971 what did David Baltimore propose to distinguish viruses

based on its genome composition (rna or dna), the route used to express messenger RNA (mrna) and mechanism of replication

how did the ICTV classified viruses

a. based on shape and size

b.genome composition

c. based on its DNA

d. capsid symmetry

e. envelope

f. size of virion

g. host range

B, D, E, F, G

how does penetration/uncoating affect the cell membrane

in three methods **endocytosis** which is when the entire virus is engulfed and enclosed in a vacuole or vesicle

and **fusion** which is when envelope merges directly with membrane resulting in nucleocapsids entry into cytoplasm

**injection of nucleic acid**

what tissues of host range does measles affect

receptors widespread