Bio Chapter 7 Viruses

HIV

(human immunodeficiency virus) retrovirus, RNA virus, mutates at an extremely high rate, and attacks human immune cells -it attacks the immune system by killing and hiding in white blood cells (helper T cells) and turning the immune system against itself

øWhat is the difference between a primary and secondary immune response?

-The primary immune response of the body to antigen occurs on the first occasion it is encountered. Depending on the nature of the antigen and the site of entry this response can take up to 14 days to resolve and leads to the generation of memory cells with a high specificity for the inducing antigen. The humoral response, mediated by B cells with the help of T cells, produces high‐affinity and antigen‐specific antibodies. -The secondary response of both B‐ and T cells is observed following subsequent encounter with the same antigen and is more rapid leading to the activation of previously generated memory cells. This has some quantitative and qualitative differences from the primary response.

Get HIV by

1.Having sex with someone that has it 2.sharing a needle with someone that has it 3.being born with it because your mother has it

4 RNA viruses

1.Influenza 2.HIV 3.Measles 4.Polio

Influenza virus 3 facts

1.combines with other viruses to become stronger 2.only directly attacks the respiratory system

øHow does a virus infect a cell?

A bacterial virus infects the cell by attaching fibers of its protein tail to a specific receptor site on the bacterial cell wall and then injecting the nucleic acid into the host, leaving the empty capsid outside.

envelope

A lot of viruses (but not all) also have a surrounding

Distinguish between a retrovirus and a virus. Which is less stable or mutates more?

A retrovirus is made from RNA and it com pies its own genetic material while a virus is made from DNA and it uses host cells enzymes and nucleotides to copy its genetic material. Retro is harder to fight because it mutates very quickly.

øDescribe a virus. Give some examples.

A small protein sac of genetic material that that gets inside a cell and infects it. ex. HIV, measles, mumps, etc

Bacteriophage

A virus that infects bacteria is called

Polio

Affects the spinal cord leaving many infected individuals paralyzed, infection rate dropped by 99% when vaccine was introduced in 1955.

Nucleic Acid, coat or capsid

All viruses are composed of_________ __________, such as DNA or RNA and a protein _______

ARV stands for

Anti Retro Viral

øWhy is a virus considered an intracellular parasite?

Because it is inside a cell and it is a bug. It attacks and kills what is in its path.

øWhere do viruses enter?

Because viruses enter host cells to reproduce, it is difficult to develop a drug that kills viruses without harming the living host. Ex flu, chicken pox, measles, mumps, hepatitis, HIV, etc.

Herd immunity

Being protects in a circle of people or having lots of people who are vaccinated so the virus doesn't spread.

Measles

Causes fever and red rash on the skin, US declared free of this virus in 2000 but had returned, very infectious.

Smallpox

Causes small puss filled pumps on the skin, infection of cowpox created immunity against the virus.

Heliotrope Cyanosis

Discoloration of the face and ears when the lungs are desperate for air.

An RNA molecule is more stable than a DNA molecule allowing them to mutate more often

False

Approximately 50% of people exposed to measles that are not immune actually get sick from the virus.

False

Approximately 70% of parents choose to vaccinate their children.

False

In the 1500s 1 in 10 children died before the age of 5.

False

Vaccines contain weakened or dead parts of antigens, making it easier fro immune system to win quickly.

False

Vaccines got there name from the word for sheep

False

In order to infect a cell a virus must

Have a special protein on its surface that can interact with a protein on the surface of the host cell

Immuno-compromised

Having an impaired immune system does not allow one to properly fight off or destroy dangerous viruses

øViruses can affect what?

Humans, Plants, Animal, Bacteria

A scientist is trying to determine whether a virus that caused disease in dogs could be transmitted to humans. Which research procedure was most likely chosen for this project

Identify receptors used on the dog cell and compare them to human cell receptors

Pertussis

Inflammation of the lungs, lots of coughing, commonly affects infants and young children.

What is the outer protein coat of a virus called? What additional structure can be on the outer surface of some viruses?

It is called a capsid it can also have an envelope..

The cycle of viral infection that will cause DNA to become integrated into the bacterial DNA is

Lysogenic cycle

During which cycle is the host cell destroyed?

Lytic cycle

cell membrane

Many of these envelopes include part of the ______ ____________ of the type of cell they infect- making it easier to enter other cells of the same type

øHow does HIV attack the immune system? Do people die from HIV or AIDS?

People die from AIDS acquired immune deficiency syndrome. There immune system becomes attack by the virus attacking the T-cells so there immune system becomes weak and they get a common cold or flu and because they now have AIDS their immune system id too weak to fight off the infection.

øVirus

Protein Sac of genetic material

ribosomes, protein

RNA polymerase and cell __________ are used to make viral __________ to make viral DNA

øTougher to fight

RNA viruses or retro viruses because they mutate quickly

Temporary vs Permanent Immunity

Temporary is when you have immunity until you get the disease while permanent is when you previously had the disease or the vaccination making you immune

lyse, lytic

The viral components and the viral DNA then get put together to form copies of the original virus. These copies then break out of the cell or _____________ the cell in what is called the _____ cycle.

lysogenic

The_________ cycle begins the same way with the viral DNA being injected into the cell.

Eradicate

To completely destroy or put an end to a disease or iris. People though measles was eradicated but it came back.

Families can claim religious exemption to avoid having their children get the required vaccinations to attend school

True

Vaccines can wear off after a few years, so some require booster shots to provide the appropriate immunity.

True

øPrimary Immune Response

Vaccine creates this response which will protect the body if ever infected again

øWhat does it mean if a virus is latent or dormant?

Virus latency (or viral latency) is the ability of a pathogenic virus to lie dormant (latent) within a cell, denoted as the lysogenic part of the viral life cycle. A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection.(existing but not yet developed or manifest; hidden; concealed.)

Which shows the the steps of a viral infection in the proper order?

Virus locates host cell-> penetrates cell membrane-> enters nucleus->alters host cell DNA->host cell produces copies of virus

Cells

Viruses can only spread (or copy themselves) using

DNA Polymerase

Viruses use machinery of a cell, specifically _________ __________, to copy it's own viral DNA

øWhat is a vaccine?

a substance used to stimulate the production of antibodies and provide immunity against one or several diseases, prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease.

How big is a virus? Is it living? What can it infect? Is it species or tissue specific?

a virus is very small, smaller than a human cell. are not considered "alive" because they lack many of the properties that scientists associate with living organisms. Primarily, they lack the ability to reproduce without the aid of a host cell, and don't use the typical cell- division approach to replication. It can infect animals, humans, plants, bacteria etc. Most viruses infect specific host cells and tissues.

øWhat is a bacteriophage?

a virus that parasitizes a bacterium by infecting it and reproducing inside it.

Viruses are not considered to be

alive

Viruses

are all about the same size and shape

HIV treatment should contain

at least 3 different drugs from 2 different classes.

Process involving the replication of viruses

both lytic and lysogenic cycles

A lytic infection concludes with the

bursting of the host cell

øA virus is what

can be referred to as an intracellular parasite because it lives inside a host cell

øSecondary Immune Response

can be stimulated by exposure to a virus if previously vaccinated for that virus, is a stronger response than a primary immune response, and can be attributed to the presence of antibodies.

øCan be what?

either double or single stranded

øCapsid protein coat

encloses genetic material

øVaccination

injection of weakened or dead pathogens (or their toxins) into a healthy person to induce immunity

All viruses are made of proteins and

nucleic acids

øRNA Virus

retrovirus uses viral RNA transcribed into DNA then inserted into the host cells DNA to be transcribed back to viral RNA

øVirulence

strength of the disease

øEnvelope

surrounds capsid, studded with receptors that help virus enter cells ( most viruses have it, but not all)

In the movie outbreak the change in the protein coat of the ebola virus allowed the second strain to become airborne.

true

øDNA Virus

uses host cells enzymes & nucleotides to copy its genetic material

Lysogenic cycle

viral replication in which a viral genome is replicated as a provirus without destroying the host cell - host cell divides normally and reproduces the viral DNA along with its own. Virus does not reproduce right away - they wit to become active. ( not doing anything until it is triggered) HIV ( joins DNA when cell divides)

øLytic Cycle

viral replication that results in the destruction of the host cell and the release of many virus particles (active, causes damage, feel symptoms faster)

Why can't a virus reproduce on its own?

virus dont have its own body machinery, it always need a host to reproduce as it uses it machinery to reproduce

A prophage is

virus that infects a prokaryotic cell such as a bacterium

phagocytes

what type of immune cell is the first to mount to a counterattack on bacteria in the body