BIOB51H3 Lecture Notes - Lecture 15: Reverse Transcriptase, Rna Virus, Retrovirus

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14 Dec 2012

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Aids: aquired immune deficiency syndrome, caused by hiv. Aids is one of the most important selection factors in the human population. About 25% of people with hiv are women: biology of hiv. Hiv 1 strain most common type of hiv found in north america. Hiv is a retrovirus (rna virus) and it has to go through reverse transcriptase to hijack the machinery of cells to produce more of its self. Bind to the cell membrane and empty content into cell. Then spliced into host genome and the host transcribes more hiv.

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1. A mutation in the gene encoding the integrase enzyme rendersthe protein non-functional. How would the affect the HIV infectioncycle?

Formation of the provirus would bestopped.

Reverse transcription would nolonger be possible.

The gp120 glycoprotein would nolonger be able to bind to the CCR5 receptor.

Cutting and assembling the capsid would be halted.

2. If the viral gene is AUGCCCAGG and the mRNA used to make theviral protein is UACGGGUCC, then the virus is a :

Negative strand RNA virus

Double stranded DNA virus

Retrovirus

Positive strand RNA virus

3. Would treating prions with enzymes that digest nucleotides bean effective neutralization method?

No, prions lack amino acids.

Yes, prion nucleic acids would besusceptible to enzymatic digestion.

No, prions lack phosphodiesterbonds and would not be subject to digestion by these types ofenzymes.

Yes, the bonds between the amino acids would be hydrolyzed.

4. Most Americans born before 1970 have a permanent scar ontheir shoulders from the smallpox vaccine. Why don't youngerAmericans have one?

Smallpox has been eradicated by aworldwide vaccination program.

Smallpox is no longer lethal.

A safer less damaging vaccine wasdeveloped in the early 1970's.

The vaccine is no longer effective due to antigenic shift.

5. What kind of pathogen would retain its ability to causeinfections after being treated with powerful proteolytic chemicalsthat would destroy all proteinaceous material?

A viroid

6. Select all of the false statements concerning AIDS.

AIDS kills the patient.

Patients die as a result ofopportunistic infections.

AIDS shuts down the immunesystem.

HIV therapy (HAART) can clear thevirus from the bloodstream.

HIV therapy (HAART) can clear the virus from the patient'sbody.

7. Why do viruses only infect specific types of cells?

Viruses only attack epithelialcells, such as the cells lining the lungs.

If a host cell is weakened, viruseshave an easier time infecting it.

The initial choice is random butonce a cell type is chosen it becomes the preferred host.

The host cells have the correctsurface receptor that the virus can fit into.

Viruses infect the first cells they encounter.

8. Nucleotide analogs are a class of drugs that are highlyeffective against many types of viruses. They work by halting thereplication of viral genes. They are equally effective at stoppingthe spread of prion diseases.

True

False

9. An experimental chemical has been shown to selectively cleavephosphodiester bonds. How would the affect a virus?

Dissociate the envelope

Fragment the genome

Hydrolyze the protein coating

Alter the host binding site

Digest the capsid

10. HIV uses cell surface receptors to enter host cells. Whydoes switching from a CCR5 co-receptor to a CXCR4 co-receptoreventually shut down the immune system?

	Macrophages have CCR5co-receptors.
	T-helper cells have CXCR4co-receptors.
	T-helper cells are not involved incoordinating immune responses.
	Only macrophages are killed byHIV.

crimsonsalmon160

QuestionGroup: #51 Innate immune 1

Assigned as

Homework

What is the name of a chemical substance responsible for stimulating an immune response?

Pathogen

Rotomers

Antigen

Antibody

Troll receptor

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QuestionGroup: #52 Innate immune2

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What is the purpose of secondary metabolites produced by normal flora in your body?

To aid T cells in fighting local infection

To kill infected B cells

To help balance electrolytes

To inhibit adhesion, and growth of the certain microbes

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QuestionGroup: #53 Innate immune3

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The lysozyme removes most bacteria in our foods through the saliva in our mouth, how does it do this?

The lysozyme attacks the bacteria through the blood.

The lysozyme are not strong enough to get rid of bacteria.

The lysozyme breaks down the polysaccharide walls of different bacteria.

The lysozyme will tell your body to get rid of the bacteria by vomiting.

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QuestionGroup: #54 Adapt immune 1

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In adaptive immunology, the key component is which of the following?

Antigen trigger the the production of vaccines.

Antibodies will trigger responses in the antigen which will cause an inflamation.

Antigens trigger responses of the antibodies which will recognize the antigen.

Antibodies will be able to recognize other antibodies and destroy them.

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QuestionGroup: #55 Adapt immune2

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An autoimmune induced disorder is...?

When the body's immune system attacks a tissue or organ in the body

When the immune system is not present

When the body attacks the antigens and antibodies of the immune system

When the autonomic nervous system attacks the antigen and antibodies of the immune system

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QuestionGroup: #56 Adapt immune3

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Antibodies are also called immunoglobulins and constitute part of the blood proteins. How do antibodies work?

Agglutination-- they just clump with each other (blocking antigen)

Precipitation-- force insolubility and settled out of solution along with antigens

Complement fixation-- proteins attach to antigen surface (causing cell lysis)

Neutralization-- bind to specific sites to prevent antigen attachment

All of the above

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QuestionGroup: #57 Infectious disease

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The most deadly STD is HIV, but many other viruses can be deadly. Name the most common sexually transmitted infection.

Genital human parisis virus (GHPV)

Herpes Simplex

Human papilloma virus (HPV)

Human pappathe virus tentis (HPVT)

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QuestionGroup: #58 Infectious disease2

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Microbes have developed an array of weapons to be able to go from host to host. These virulent factors are divided into several groups, but one important group is the one produced by bacteria. Name the subgroups within this bacterial group.

Retretoxin and maitotoxin

Retretoxin and butotoxin

Endotoxins and exotoxins

Lipotoxin and exotoxin

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QuestionGroup: #59 Infectious disease3

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Sexually transmitted diseases are very successful at spreading from one person to another. Name one important reason for this fact.

Mucous membranes use B cells only and are resistant to antigens

Mucous membranes in the sex organs differ from those of the skin in that they allow certain pathogens into the body

STDs are transmitted through sex only

STDs are usually caused by viruses

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QuestionGroup: #60 HIV/ AIDS

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HIV has which of the following characteristics?

It has an enzyme called reverse transcriptase which causes the DNA to reverse the nucleotide sequence in messenger RNA.

It is a retrovirus meaning that it reverses the order of protein production in that the virus affects the DNA in the cell to make the protein.

It is an anti-retrovirus meaning that it attacks the DNA causing the development of new HIV particles.

It has a short incubation period which means that the symptoms show up also immediately after infection.

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

BIOB51H3 Lecture Notes - Lecture 15: Reverse Transcriptase, Rna Virus, Retrovirus

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