BIO 440 Lecture Exam 3

In step 1, HIV uses________as template to make________ a. HIV DNA, DNA b. HIV RNA, DNA c. HIV RNA, RNA

B. HIV RNA, DNA

Explain 3 ways in which mutations can lead to antibiotic resistance among bacteria (describe 3 different mechanism of antibiotic resistance which bacteria may evolve through mutations)

1. mutations can cause changes in "target" of antibiotic so antibiotic may no longer bind to mutant target 2. mutations may lead to evolution of antibiotic efflux pumps 3. mutations may lead to new enzyme functions which can hydrolyze or chemically modify antibiotics so they are no longer active/ can no longer bind target

Retroviruses may mutate rapidly because no proofreading by reverse transcriptase, nor cellular RNA polymerase; reassortment of HIV RNA strands during assembly

1.no proofreading by reverse transcriptase 2. no cellular RNA polymerase 3. reassortment of HIV RNA strands during assembly

Which mosquitoes are vectors?

Aedes aegypti (yellow fever mosquito) Aedes albopictus (Asian Tiger Mosquito)

What are "A-B" toxins? Function of each subunit?

Exotoxins with B binding subunit and A active unti which enters cell and casues damage/disrupts normal cell function

viruses which could be transferred from mom to baby at birth and which may kill baby:

HIV, Herpes Simplex Virus

Infection with certain strains of this pathogen may predispose women to cervical cancer and men to cancer of the penis

HPV

Two viruses which may lie dormant in sensory ganglia such as trigeminal and sacral ganglia: _____

Herpes Simplex Virus

What is HAART?

Highly active antiretroviral therapy

Pathogen causes Acquired Immune Deficiency Syndrome

Human Immunodeficiency Virus

Which vaccine is used in the U.S.?

IPV

What is a disadvantage of the OPV? Advantage?

Disadvantage: can mutate, revert to virulence and cause polio Advantage: actually infects intestinal cells, causes mucosal antibodies which can block virulent virus from infecting intestinal cells. Shed in feces so indirectly can vaccinate fecal contacts ("fecal vaccination"

Are there ways to "cut out" the HIV provirus from the human chromosome? (similar to induction in temperate phage)

No

Do all viruses have an envelope?

No

Does HIV Reverse Transcriptase proofread?

No

Does HIV directly kill a person?

No

Pathogen causes Bovine Spongiform Encephalopathies (BSE) or "Mad Cow Disease"

Prions

What is IPV?

Inactivated Polio Vaccine, Salk Vaccine

Recombination of genetic information from animal, bird and human strains of this virus may lead to appearance of new highly pathogenic, highly contagious strains, causing worldwide pandemics similar to the 1918-1919 pandemic:

Influenza

Cause of chickenpox and shingles?

Varicella-Zoster Virus

Which process may involve lytic (e.g. T-even phage) and/or temperate bacteriophage (e.g. lambda phage)? a. transformation b. transduction c. conjugation

b. generalized transduction

The name of the HIV adhesin is ____________________ which binds to ____of human cells a. gp 41: sialic acid b. gp 120; CD4 c. neuraminidase; sialic acid

b. gp 120; CD4

(Historically....) How are vaccine influenza viruses grown? a. in human diploid cell culture b. in embryonated eggs c. in mice d. in humans

b. in embryonated eggs

Toxoid

modified exotoxin which does not cause harm but which can stimulate production of protective antibodies/antitoxin

A heritable change in DNA sequence (or RNA sequence in RNA viruses) a. anomaly b. mutation c. DNA damage d. pyrimidine dimer

b. mutation

Is HIV a zoonosis? a. yes b. no

b. no

HIV reverse transcriptase function (step 1): a. uses HIV DNA as template to synthesize complementary RNA b. use HIV RNA as a template to synthesis complementary DNA c. inhibits function of normal cellular RNA polymerase in host cells d. uses HIV RNA to make complementary RNA

b. use HIV RNA as a template to synthesis complementary DNA

Exotoxin

bacterial protein toxins

Describe poliovirus

naked RNA virus

You have successfully developed a vaccine against HIV. This vaccine stimulates productions of antibodies against gp120 of HIV. Why would this vaccine protect people against AIDS? ___neutralizing antibodies block attachment of HIV to host cells______

neutralizing antibodies block attachment of HIV to host cells______

Influenza virus: Tamiflu inhibits influenza neuraminidase. How does this decrease influenza virus replication?_____

newly released viruses will clump, decreases infection of neighboring cells, thus decreases replication and damage

Does cellular DNA dependent RNA Polymerase=Cellular RNA polymerase proofread?

no

What is the source of the viral envelope? a. viral enzymes synthesize the phospholipids which make the envelope b. viral enzymes secrete a slime layer like polysaccharide which develops into the envelope c. "stolen" host cell membranes d. Both "a' and 'b"

c. "stolen" host cell membranes

Host cell ribosomes translate HIV mRNA into "polyproteins" Which HIV enzyme cuts the polyprotein into individual functional HIV proteins? a. integrase b. neuraminidase c. HIV protease

c. HIV protease

Describe the receptors HIV uses to attach to cells a. HA b. sialic acid c. HA d. co-receptors e. both CD4 and co-receptor

e. both CD4 and co-receptor

Drugs used to treat HIV infections include: a. beta lactam antibiotics b. protease inhibitors c. amphotericin B d. nucleoside analogues ex AZT e. BOTH "g" and "i"

e. both g and i

When the live R strain was mixed with dead S strain and injected into mice, what was the result? a. the mice lived b. half the mice died, half became paralyzed but lived c. the mice all died d. the mice lived and became resistant to living, virulent S strain

c. all the mice died

As a result of mistakes made by the RNA dependent RNA polymerases, influenza viruses demonstrate: a. antigenic confusion b. antigenic shift c. antigenic drift d. lysis

c. antigenic drift

Which drug(s) may block HIV fusion? a. gp/fusion inhibitor b. coreceptor antagonist/entry inhibitor c. both

c. both

How does HIV escape from the host cell? a. uses neuraminidase b. lysis c. budding

c. budding

In E.coli, the F factor carries genes for this process. a. transformation b. transduction c. conjugation

c. conjugation

What is the HIV adhesin? a. HA b. RNA c. both DNA and RNA d. neither

c. gp120

How will HIV modify the cell membrane before it escapes? a. adds HA b. adds NA c. inserts gp120 and gp41

c. inserts gp120 and gp41

Why may some people be resistant to HIV infection, or if infected, do not progress to AIDS? a. mutant CD4 b. mutant HA c. mutant coreceptor d. none of these

c. mutant coreceptor

Conjugation in E. coli a. requires the presence of a special "S" plasmid, the "sex plasmid" and cell to cell contact b. requires formation of a sex pilus which permits a F+ male to make physical contact with a F- female c. permits transfer of mRNA to a recipient cell d. all of the above are TRUE

c. permits transfer of mRNA to a recipient cell

The "holes" formed in a lawn of bacteria by bacteriophage are called: a. pores b. vesicles c. plaques d. pustules

c. plaques

Once the envelope of a virus is damaged: a. its infectious dose ID-50 decreases b. the viral contents triggers endocytosis by host cells ("Trojan Horse" effect) c. the virus is no longer infectious d. the virus becomes hyper-infective and causes rapid lysis o f host cells

c. the virus is no longer infectious

What is the function of HIV integrase inhibitors? a. to prevent provirus formation b. to inhibit reverse transcription c. to block insertion of provirus into human chromosome

c. to block insertion of provirus into human chromosome

What is advantage of IPV?

cannot cause polio as virus is inactivated. Disadvantage:cannot stop virulent replication in intestines but can block spread to nervous system, prevents paralysis.

Of the components listed below, circle those which ALL viruses contain (none, one or more may be correct)3 capsid envelope DNA RNA protein "coat" nucleic acid (either DNA or RNA, but NOT both)

capsid, protein coat, nucleic acid

Concerns fro pregnant moms when it comes to Zika virus?

Zika virus can invade babies nervous system and inhibit neural development. Dramatic "microcephaly"

HIV infections can destroy ___________________________(name specific type of cell) which can cause collapse of a patient's immune system a. CD4 + T helper lymphocytes b. CD8 + T helper lymphocytes c. CD4 + Macrophages d. All of the above

a. CD4 + T helper lymphocytes

Describe Zika Virus

enveloped RNA virus

With regard to bacteriophage replication, which of the following steps would be the 1st step? a. Adsorption/attachment b. biosynthesis c. injection of nucleic acid d. assembly

a. adsorption

Which host cell will make copies of HIV RNA? a. cellular DNA dependent RNA polymerase=cellular RNA Polymerase b. cellular DNA Polymerase c. HIV DNA Polymerase

a. cellular DNA dependent RNA Polymerase=cellular RNA polymerase

Which 2 HIV proteins must be functioning for HIV fusion to occur? a. co-receptor and gp41 fusion protein b. HA and NA

a. co-receptor and gp41 fusion protein

in general, which of the following are most harmful to cells? a.. frameshift mutations b. point mutations c. silent mutations d. BOTH "b" and "c" e. NONE of the above

a. frameshift mutations

Specialized transduction a. involves transfer of only those bacterial genes near the insertion site of a prophage b. random transfer of any bacterial chromosome fragment c. F factors formed into plasmids d. competent cells

a. involves transfer of only those bacterial genes near the insertion of the prophage

In the lysogenic cycle of replication, "induction" is triggered by destruction of the ____ a. phage repressor protein b. phage operator c. phage inducer protein d. phage promoter sequence

a. phage repressor protein

What may have enriched the human population with the mutants escribed in the previous question? a. selection for mutants by an infectious disease b. lack of good nutrition c. previous infection with H1N1 virus

a. selection for mutants by an infectious disease e.g. bubonic plague or smallpox

Why does the person experience immune system collapse? a. thelper coordinate responses of othe rlymphocytes, crucial for humoral and cell mediated immune responses b. person can no longer make HA and NA

a. t-helpers coordinate responses of other lymphocytes, crucial for humoral and cell mediated immune responses

Prophages are important in medical bacteriology because: a. they can carry toxin genes such as the shiga-like toxin gene of E. coli O157-H7 b. they will kill all pathogenic bacteria c. they will infect human immune cells, leading to immunodeficiency d. they are NOT important in medical bacteriology

a. they can carry toxin genes such as the shiga-like toxin gene of E. coli O157-H7

How did your patient most likely become infected with E. coli O157:H7? a. vehicle transmission: ate fecal- contaminated hamburger or raw vegetables b. airborne transmission c. parenteral: inoculation under the skin d. arthropod vector transmission

a. vehicle transmission: ate fecal- contaminated hamburger or raw vegetables

Is avian influenza H5N1 a zoonosis? a. yes b. no

a. yes

One reservoir of E.coli O157:H7 is cattle, thus this pathogen is: a. zoonotic b. viral c. prional d. trouble

a. zoonotic

Which of the following statements is false? e. Chronic Wasting Disease of deer and elk is present in the United States f. Scrapie is a prion disease of sheep and goats g. Human prion diseases may be transmitted through consumption of prion contaminated meat h.Prion diseases can NOT be transmitted between 2 different animal species

h.Prion diseases can NOT be transmitted between 2 different animal species

Neutralizing antibodies

antibodies that block attachment of a pathogen or toxin

Average CD4+ T helper lymphocytes in human blood -1200 Th/microliter of blood. If a person has been chronically infected with HIV, when will the person experience immune system "collapse"

b. Th<200/ul

Consequence of not being able to proofread?

high mutation rates

Patients who are severely immunocompromised should not receive which types of vaccines below? a. heat-inactivated/killed vaccines b. attenuated "live" vaccines c. subunit vaccines (e.g. only surface proteins from a pathogen) d. vaccines made through genetic recombination in Saccharomyces

b. attenuated "live" vaccines

An RNA dependent DNA polymerase describes a. cellular RNA polymerase b. cellular DNA polymerase c. viral transcriptase d. HIV reverse transcriptase

d. HIV reverse transcriptase

Which of the following statements is/ are TRUE with regard to mutations: a. are changes in DNA nucleotide/base sequence b. are sometimes harmful to bacteria c. can sometimes lead to antibiotic resistance d. ALL of the above are true

d. all of the above

Prokaryotic transformation: a. can occur naturally in Streptococcus pneumoniae bacteria b. requires competent bacterial cells c. requires uptake of naked DNA from the environment by cells d.ALL of the above are correct e. ONLY "a" and "b" are correct

d. all of the above are correct

What are "Hfr" E. coli cells? a. E. coli carrying the F factor/plasmid integrated into the bacterial chromosome b." High frequency of recombination" E. coli c. E coli donor/"male" capable of DNA exchange via conjugation with recipient/"female" d. ALL of the above are true

d. all of the above are true

Which cells in humans have the HIV receptor? a. dendritic cells b. macrophages c. T helper lymphocytes d. all of these

d. all of these

Homologous recombination: a. is combining genetic information from 2 organisms. b. requires several proteins and enzymes c. does NOT occur in bacteria d. both a and b are correct

d. both a and b are correct

Which HIV enzyme inserts the HIV provirus into the human chromosome? a. protease b. neuraminidase c. sialidase d. integrase

d. integrase

Newly formed influenza viruses would naturally clump together if _____________is inhibited by "Tamiflu": a. sialic acid b. hemagglutin c. gp41 d. neuraminidase

d. neuraminidase

An Hfr tetracycline resistant (chromosomally encoded) E.coli O157:H7 donor mates with an antibiotic sensitive, non-toxin producing E.coli F- recipient in the intestinal tract of one of your patients (who has profuse diarrhea). Which of the following is LEAST LIKELY to occur? a. The recipient may become tetracycline resistant b. The recipient may acquire the Shiga-like toxin gene c. The recipient may become tetracycline resistant AND acquire the Shiga-like toxin gene d. The recipient will also become an Hfr donor

d. the recipient will also become an Hfr donor

How do viruses acquire their envelopes?

stolen host cell membranes

Are there multiple drugs which can inhibit function of HIV reverse transcriptase?

yes

May HIV cause latent infections?

yes

Is there pre-exposure prophylaxis to prevent infection with HIV?

yes, eg Truvada, 2 reverse transcription inhibitors

Is there a vertical transmission of HIV from mom to baby?

yes, even through breast milk

Endotoxin

Lipid A of LPS of gram-negative bacterial cell walls

Transmission of Zika Virus?

Mosquito, sexual, mom-to-baby/transplacental

How is poliovirus transmitted?

fecal-oral transmission

Where do polioviruses replicate?

1st in intestines, shed in feces; in some people, invades nervous system, replicates in neurons, causing inflammation "myelitis" which may lead to flaccid paralysis, death by suffocation (use of "iron lung") or leg paralysis.

What is OPV?

Oral Polio Vaccine, Sabin Vaccine

Are there anti-HIV drugs which can inhibit this enzyme? (HIV Protease)

Yes

Is HIV an enveloped virus?

Yes

Is a person with AIDS at risk of dying from an opportunistic pathogen?

Yes

Is there a global polio eradication campaign currently?

Yes

Will this modification (insertion of gp120 and gp41) mark the infected cell for destruction by the immune system?

Yes

Why is it so hard to develop a vaccine against HIV? Why does HIV rapidly evolve drug resistance?

1. reverse transcriptase does not proofread-->lots of mutations 2. cellular RNA polymerase does not proofread-->lots of mutation 3. HIV "packages" 2 genomic RNA copies, increases genetic diversity

Does HIV use RNA or DNA?

RNA

When the HIV infected cell is activated to start HIV replication, what will be the template for HIV RNA synthesis? a. HIV provirus b. HIV RNA c. human chromosomal RNA

a. HIV provirus

When finished, HIV Reverse Transcriptase has made a ds DNA copy of the HIV genetic information; this DNA copy is called the______ a. HIV prophage b. HIV provirus c. HIV prion d. HIV promoter

b. HIV provirus

RNA viruses must rely on the enzyme _________________ to copy their genomes: a. reverse trancriptase b. RNA-dependent RNA polymerase c. DNA polymerase d. RNAse

b. RNA-dependent RNA polymerase