question

Outside the host, virus cells are made up of: ____ and ___.

answer

protein shell (capsid) and nucleic acids

question

virion

answer

a fully developed particle outside of a host cell

question

TF: viruses have DNA and RNA

answer

False: Viruses can have DNA OR RNA, but never both

question

capsid

answer

protein structure surrounding a DNA or RNA segment in a virus; outer part of virus

question

capsomeres

answer

distinctive arrangement which makes up capsids

question

helical viruses arrangement

answer

protein coat arranged in a cylindrical helix with the nucleic acid in the center.

question

polyhedral or icosahedral

answer

many-sides in a structure; capsid made of triangular capsomeres

question

bacteriophage structure

answer

capside head(icosahedral) and a complex tail (helical) -used in the attachment and release of nucleic acid

question

Types of virus arrangements (4)

answer

complex helical enveloped polyhedral or icosahedral

question

bacteriophage

answer

a virus that parasitizes a bacterium cell; infects and reproduces inside of it.

question

EXTRAcellular state of viruses:

answer

-capsid surrounds nucleic acid -some have phospholipid envelope -protects and recognizes host cells (outer layer)

question

INTRAcellular state of viruses:

answer

CAPSID (protective shell) REMOVED!!!!!! virus exists only as nucleic acid (no longer needs its own protection, recognition etc. b/c it uses host cell for that)

question

envelope composition

answer

composed of phospholipid membrane outside of capsid; has proteins that help stick to host

question

glycoprotein spikes

answer

may protrude from viral envelope for attachment; made of virally-coded proteins

question

TF: glycoprotein spikes are masters at mutation.

answer

TRUE! glycoprotein spikes are masters at mutation in order to avoid detection by the host's immune system.

question

viruses are...

answer

highly specific to their adapted host (receptor/anti-receptor)

question

"Naked" viruses

answer

viruses without an envelope; released by exocytosis and may cause lysis and death of host cell

question

naked virus mode of attachment

answer

capsomeres

question

Why are viruses so hard to treat?

answer

Because the virus uses everything the host cell has, so if you treat the "virus," you're also "treating"/damaging the host.

question

THREE basic groups of viruses

answer

ANIMAL PLANT BACTERIAL

question

TF: viruses are hard to study because you have to be able to grow a host

answer

TRUE! Most viral studies come from the use of bacteriophages (so we can grow them in agar cultures).

question

TF: animal cell viruses are cultured in living animals, embryonated eggs, or cell culture

answer

TRUE

question

loss of contact inhibition

answer

this allows growth in lumps or masses (tumors); will grow on top of each other

question

immortalization

answer

unlimited cell production; will divide forever

question

attachment (lytic and lysogenic cycles)

answer

virus attaches to specific cell wall receptors using its viral receptors

question

entry (penetration) lytic and lysogenic cycles

answer

viral enzymes break down the cell wall and viral genes are inserted into the host cell

question

maturation (lytic cycle)

answer

viral gene copies are packaged into viral capsids and the viral proteins are assembled into complete virions

question

Assembly and maturation (eucaryotic)

answer

leads to the production of new virions which may be released gradually from the cell with or without lysis. Infected cells can produce virions for many days following the initial infection

question

burst time

answer

The time between attachment and phage release ;It is 20 to 40 minutes usually.

question

lysogeny and integration

answer

during infection of the host cell the viral genes are spliced or inserted into the host chromosome; happens prior to viral synthesis occurring in the host

question

prophage

answer

(viral) genome inserted and integrated into the circular bacterial DNA chromosome; may remain intergrated in the host DNA w/o immediate effects

question

lysogen

answer

a bacterium containing a prophage

question

lysogen toxin production

answer

Since lysogens now have DNA from a virus and a bacteria, the host may exhibit new toxins that previously didn't exist (Scarlet Fever toxin etc)

question

animal cell virus "uncoating"

answer

host cell removes the capsid from the virus during endocytosis releasing viral genes (in this case DNA) and viral enzymes into the host cytoplasm

question

Most animal cell viruses are uncoated by ____

answer

by enzymes in the host cell cytoplasm.

question

TWO things that happen to ANY DNA inside a nucleus are _____ and _____.

answer

1. REPLICATION 2. TRANSCRIPTION

question

transcription is:

answer

the production of RNA from DNA

question

The viral proteins synthesized in the cytoplasm MUST include _____

answer

capsids! All viruses have capsids, so this is where the proteins are made to construct capsids

question

If the DNA virus infecting the animal cell was an ENVELOPED virus, what else must be synthesized in the cytoplasm?

answer

GLYCOPROTEIN SPIKES

question

Biosynthesis of an RNA virus is different than a DNA virus...T/F

answer

true

question

After uncoating, do RNA viruses need to go to the nucleus of the host cell? Explain

answer

NO. RNA is used to make new virus proteins, which occurs in the cytoplasm of the cell. Therefore, there is no need to involve the nucleus.

question

Where are most DNA viruses assembled and released from?

answer

They are assembled in the nucleus and released into the cytosol of the cell.

question

Where are most RNA viruses assembled?

answer

The cell cytoplasm (remember, they don't need nucleus involvement b/c they have no DNA

question

Enveloped viruses cause _____ infections

answer

persistant. This is because they bud from the host cell instead of burst from it, which leaves the host cell alive for a period of time to make more viruses

question

Non-enveloped viruses ("naked" viruses) are released through ______.

answer

exocytosis, which means DEATH to the host cell

question

Why is uncoating necessary for phages?

answer

Because uncoating is the process by which nucleic acids and other genetic information is made available to the host cell

question

latency

answer

viruses may enter cell and remain "dormant" for some time before causing damage no clinical signs are obvious but the viral infection can still be transmitted

question

TF: all latent viruses become incorporated into host chromosomes. This is how they can remain dormant for so long.

answer

FALSE: some latent viruses do incorporate themselves into the host chromosomes (HIV), but some latent viruses do not incorporate into host chromosomal make up (herpes)

question

When a provirus is incorporated into a host's chromosomes, the condition is _______.

answer

Permanent. This means that it will be passed on through anything with chromosomal contact (through offspring) Ex: HIV

question

Where does multiplication of RNA viruses take place?

answer

Host cell CYTOPLASM

question

budding

answer

enveloped cells exiting the host cell without lysing the host

question

TF: nonenveloped usually lyse the cell upon exit

answer

TRUE: nonenveloped viruses will acquire part of the plasma membrane of the host cell on its way out, and form this into it's own new envelope. This lyses the host cell

question

cancer

answer

A cancer is the uncontrolled multiplication of a given type of cell in the body. The tissue is then called a tumor which may be malignant or benign. The suffix "oma" is associated with tumors and the prefix designating the type of tissue affected.

question

benign

answer

does not spread/cannot metastasize

question

malignant

answer

tumor/cancer that has the ability to metastasize

question

oncogenes

answer

viruses that control cell division and holds genes

question

proto-oncogenes

answer

viruses may cause mutations also c-oncogenes

question

Oncogene activators

answer

ultraviolet light radiation carcinogens (cancer causing chemicals) viruses

question

TF: All oncogenic viruses have the ability to integrate into the host cell's DNA and replicate there.

answer

TRUE

question

Signs that cells have become cancerous:

answer

1. Lose contact inhibition 2. express viral antigens on surface 3. chromosomal abnormalities 4. loss of adherence requirements

question

Methods of Oncogene Activation:

answer

1. transduction 2. translocation 3. gene amplification 4. muation

question

oncogenic viruses:

answer

1. HPV- cervical cancer 2. Hepatitis Viruses-liver cancer 3. Herpes simple/herpes Zoster-lymphoma 4. Epstein-Barr-Burkitt's lymphoma 5. Human T-cell Leukemia virus-"hairy" leukemia Any virus that causes tumors or cancers

question

scrapie

answer

slow-progressive sheep disease, causes neurological issues which then manifest as sheep scraping skin raw

question

True

answer

T/F -Prion PrP converts cellular PrP into prion PrP by inducing conformational change

question

Give a few examples of "unconventional agents" diseases; diseases caused by prions

answer

Mad Cow Scrapie Creutzfeldt-Jakob disease

question

reverse transcriptase

answer

enzymes that allow synthesis of DNA from RNA

question

Complex Shape

answer

multi-part viral particles displaying "tail" fibers, "tail" sheath, capsid "head" Example: Bacteriophages

question

Protection by capsid

answer

The outer layer protects the virion from enzymes, and chemicals outside of the host cell. Example; intestinal viruses are resistant to acids and digestive enzymes in the GI tract.

question

Bacteriohages

answer

viruses that attack bacteria

question

Attachment

answer

Virus engages host cell by chance collision. Viruses do not move on their own. (Lytic & Lysogenic)

question

Entry

answer

Chemical interaction causes the contraction of the tail and it injects DNA into bacterial cell. Leaves ghost phage behind. (Lytic & Lysogenic)

question

Biosynthesis

answer

viral genes will force the production of gene copies and synthesis of viral proteins (Lytic )

question

Assembly

answer

Viral parts come together, chemical reactions bring and glue pieces together. (Lytic & Lysogenic)

question

Lysis

answer

the host cell will burst (lyse) releasing new virions or lysogenic virions into the surrounding environment (Lytic & Lysogenic)

question

Lysogeny

answer

the bacteriophage DNA is integrated into the bacterial DNA. As the cell goes through binary fission, it copies the bacteriophage DNA is copied with it. (Lysogenic only)

question

Induction

answer

Due to environmental or metabolic stress changes, the prophage becomes active and begins the synthesis of new virions (Lysogenic only)

question

Budding

answer

process by which enveloped viruses are released and acquire their envelope. Gradual Process

question

Uncoating

answer

When nucleic acid is released into cytoplasm.

question

Prions

answer

Proteinaceous infectious agent found deposited in the brain tissue of animals infected with spongiform encephalopathies. Lacked nucleic acids. Infections have a long period of latency (few up to 60+ years)

question

Endocytosis

answer

the cell may participate in the infection process by fusing with and engulfing, the viral particle after attachment (lysogenic cycle)

question

proto-oncogenes

answer

Genes that play a role in cell division Viruses cause 20-25% of human cancers by carrying copies of oncogenes, by promoting those already present, or possibly interfering with normal repression

question

Cell cultures

answer

cells isolated from an organism and grown on media or in broth. Continuous cultures come from tumor cells and can divide continually

question

retrovirus

answer

transcribes DNA from RNA

question

prions

answer

infectious protein particles that lack nucleic acids and replicate by converting similar, normal, proteins into new prions.

question

DNA or RNA Linear or circular Single stranded or double stranded

answer

Viral genome

question

Lytic cycle

answer

will cause lysis of the bacterial host soon after infection by bacteriophage

question

Lysogenic state

answer

Latent cycle phage integrate into host genome

question

bacteriophage or phage

answer

Viruses can infect bacteria, this is known as

question

glycoprotein spikes

answer

attachment proteins

question

Lytic cycle stages

answer

attachment penetration biosynthesis maturation lysis

question

Lysogenic stages

answer

attachment penetration lysogeny/integration cell reproduction induction lysis

question

Virus

answer

-minuscule, acellular infectious agent having either DNA or RNA -causes many infections of humans, animals, plants, and bacteria -causes most of the diseases that plague the industrialized world

question

Virus

answer

-cannot carryout any metabolic pathway -neither grow or respond to the enviroment -cannot reproduce independently -recruit the cells metabolic pathways to increase their numbers -lack cytoplasmic mmb, cytosol, organelles (with the exception with the envelope) -Have a extracellular and intracellular state

question

prion and viroid

answer

little pathogenic particle

question

type of material, size, cells they attack, capsid coat material, shape, presence or absence of envelope

answer

What are the six ways viruses differ?

question

Viral replication

answer

-dependent on hosts' organelles and enzymes -stages include: Attachment, entry, synthesis, assembly, release

question

They help viruses attach to cell

answer

What is the purpose of the glycoproteins?

question

Virion

answer

Bacteriophage goes into host cell then it turns into a ______.

question

Lysogenic conversion

answer

______ ______ occurs when phages carry genes that alter phenotype of a bacterium.

question

1. envelope 2. Eukaryotic 3. cell wall

answer

Replication of animal viruses ---same basic replication pathway as bacteriophages -Differences result from: -1. Presence of _____ around some viruses. -2. _______ nature of animal cells. -3. Lack of ____ ____ in animal cells.

question

1. Chemical 2. tails or tail fibers 3. glycoprotein

answer

Replication of animal viruses -Attachment of animal viruses -1. _______ reaction. -2. Animals do not have ____ or ____ ____. -3. Have ________ spikes or other attachment molecules that mediate attachment

question

1. nucleus 2. cytoplasm

answer

Replication of animal viruses -Synthesis of animal viruses ---Requires different strategy depending on its nucleic acid -1. DNA viruses often enter the ______. -2. RNA viruses often replicate in the _______.

question

1. # - depends on TYPE of virus. also depends on the SIZE and HEALTH 2. enveloped 3. naked

answer

Replication of animal viruses -Assembly and release of animal viruses --1. The Number of viruses produced depends on ____ of virus. It also depends of the ____ and initial ____ of host cell. --2. _______ viruses cause persistent infections. --3. _______ viruses are released by exocytosis or lysis.

question

provirus

answer

integrated vDNA can be stably integrated for months to years before becoming activated (ex: HIV)

question

Neoplasia

answer

-Uncontrolled cell division in multicellular animals -A mass of this is called a tumor.

question

UV light Radiation carcinogens viruses

answer

What are the four enviromental factors that contribute to the activation of oncogenes?

question

20-25%

answer

Viruses cause ____% of human cancers -

question

Prions

answer

-Proteinaceous infectious agents (sm particles of protein) -Cellular PrP - protein (found in brain. needed for normal brain activity.) -Prion PrP - Disease-causing form with beta-pleated sheets, hard to kill -Prion PrP changes the shape of cellular PrP so it becomes prion PrP

question

Prion diseases

answer

-Fatal neurological degeneration, fibril deposits in brain, and loss of brain matter -large vacuole form in brain (spongy appearance) -Spongiform encephalopathies -only destroyed by incineration or autoclaving

question

an infectious protein

answer

What is a prion?

question

Spongiform encephalopathies

answer

- A class of diseases that includes scrapie and mad cow disease -Leave the brains of victims filled with holes. -Humans can contract by eating infected cattle

question

viral size

answer

determined with the aid of electron microscopy; different viruses have different sizes, much smaller than bacteria

question

isolation of viruses

answer

must be grown in a living cell

question

growth of viruses in embryonated eggs

answer

if the viruses grows in the egg, it is fairly convenient and inexpensive form of host for many animal viruses viral growth is signaled by death of the embryo or cell damage

question

cytocidal

answer

cell death results from lysis or impairment of cellular metabolism infected cells and tissue may undergo destruction by the immune system

question

diploid cell lines

answer

from human embryoes, can be maintained for 100 generations and used for culturing viruses that need a human host

question

HELA cell

answer

was isolated from a cancer of woman, from 1951 still used, have lost original characteristics, but have no interfered with use of the cells for viral propagation cannot have microbial contamination

question

results of lysogeny

answer

1. immune to reinfection by the same phage 2. phage conversion (host cell may exhibit new properties) 3. makes specialized transduction possible

question

Biosynthesis of DNA viruses

answer

transcirption of phasge DNA produces mRNa coding for ptoeins necessary for phage multiplication; phage DNA is replicated and capsid proteins are produced use host cell enzymes to sythesize their capsid and other proteins in the cytoplasm

question

where do RNA viruses replicate?

answer

in the host cell's cytoplasm; differences lie in how mRNA and viral RNA are produced

question

Cancer cells

answer

almost anything that alters the genetic material of eukaryotes has the potential to make normal cells cancerous; thse cancer-causing alterations to cellular DNA affects of of hte genes called oncogenes

question

oncogenes

answer

can be activated to abnormal functioning by a variety of agents like chemicals, high energy radiation, and viruses,

question

Endocytosis

answer

Type of viral entry in which the attachment of the virus induces the host cell to engulf the entire virus.

question

Retroviruses

answer

contain2 identical strands of RNA carry a set of enzymes (reverse transcriptase) which allow the synthesis of DNA from RNA allows viral intergration of Viral DNA using integrase typically enveloped/ outer proteins called spikes

question

Prion

answer

Single protein molecule, PrP proteins that cause disease

question

viral characteristics

answer

size range=20-1400 nanometers obligate intracellular parasites infects bacteria, fungi, plants, animals and humans possesses no metabolic or biosynthesis "machinery"

question

tumorgensis

answer

some viruses cause mutations that lead to uncontrolled proliferation of target cells resulting in tumor formation

question

transformed oncogenes (V-Onc)

answer

most likely responsible for certain tumors in humans and animals mutated oncogene

question

Viral oncogenes

answer

may be inherited; an oncogene disrupted by a virus;have the potential to cause tumors or cell transformation (cancers).

question

C-oncogenes

answer

normally responsible for cellular division and reproduction

question

Mutations in the oncogene are called

answer

"hits"

question

A subsequent second "hit" in an oncogene may lead to...

answer

tumor production

question

Characteristics of tumor (transformed) cells include

answer

constant log phase immortalization loss of contact inhibition loss of adherence requirements expression of aberrant tumor or viral antigens

question

receptors

answer

protein molecules on the surface

question

anti-receptors

answer

can fit into receptors

question

virus matches receptor results in...

answer

infection starting

question

viral envelope

answer

acquired from host cell during viral release; becomes portion of cell membrane; play important role in host recognition

question

infected cells and tissue may undergo destruction by...

answer

the immune system.

question

Lytic infections will continue____ until the entire host population has been destroyed

answer

amplification

question

cell reproduction in lysogenic cycle

answer

lysogenized cells reproduce normally but each daughter cell will carry a viral prophage in its chromosomal DNA. prophage can be passed through many generations of bacterial cells

question

viral infection stages in eukaryotic cells by DNA virus

answer

attachment penetration/endocytosis uncoating Viral DNA viral RNA maturation/assembly

question

vDNA

answer

enters the nucleus where its copied and "early" viral RNA is transcribed

question

vRNA

answer

initiates viral protein synthesis and leads to the production of mature virions

question

RNA retrovirus stages

answer

attachment, penetration, and uncoating reverse transcription integration latency induction vertical transmission

question

HIV is a

answer

retrovirus

question

attachment, penetration, and uncoating in retroviruses

answer

in humans the HIV virus targets a specific cellular receptor which is found on T-helper cells and other lymphocytes

question

reverse transcription in retrovirus

answer

viral reverse transcriptase enzymes become activated in the host cell and begin the synthesis of double stranded viral DNA from viral RNA

question

integration in retrovirus

answer

vDNA becomes integrated into the host chromosomes by integrase enzyme

question

induction in retrovirus

answer

at some point during the cell's life, the intergrated provirus will activate and produce vRNA that will lead to the synthesis of new virions. activated provirus will produce until cell is depleted or destroyed by the host's immune system

question

vertical transmission

answer

some proviruses can be incorporated into DNA used for sex cells which may be inherited from infected parents

question

proviruses

answer

maybe responsible for some types of cancers seen in humans and animals

question

transmission my occur between mother and child through breastfeeding or childbirth, there is NO evidence that HIV viruses are inherited via gamete DNA. T/F

answer

true

question

regulatory genes

answer

oncogenes which produce regulatory proteins which, in turn, control the miotic cycle in eukaryotic cells

MICROBIO CHAPTER 13 VIRUSES – Flashcards

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