Microbiology final exam
What are the steps in the viral replication cycle accordingly?
- Attachment. - Penetration. - Uncoating. - Replication. - Assembly. - Release.
Name one specific chemical given off by damaged cells that attracts phagocytes to the injury site.
- Histamine. - Bradykinin. - Prostagalandins.
What are the six types of cells that function in innate immunity?
- NK cells - Mast cells - Eosinophils - Basophils - Phagocytic cells.
Name one human immune cell that attack other viral infected cells.
- Natural killer cells - Helper T cells - Macrophages - Lymphocytes.
Surface barriers often produce chemicals that are anti-microbial. Name one of these substances.
- Sweat - Mucus - Tears - Saliva - Urine - Semen.
What are the two types of sof lymphocytes?
- T cells - B cells - NK cells.
What is the function of p53
A protein whose main function is to repair DNA in order to prevent altered DNA to be passed onto the daughter cell. When the damage is too extensive to be repaired, it signals cells to undergo apoptosis.
How are latent and proviruses different?
A provirus is a virus genome that is integrated into the DNA of a host cell, via the lytic cycle. Latent infection results when the provirus is transcriptionally silent rather than active.
Your patient received the Hepatitis B Vaccine. Which specific type of immunity is this? a) Acquired active immunity. b) Naturally acquired passive immunity.
Acquired active immunity.
Complement and antibodies both play a role in apoptosis. What is antibody's apoptosis function?
Antibody-directed mechanisms, including antigen cross linking, activation of death receptors, and blockade of ligand-receptor growth or survival pathways, can elicit the induction of apoptosis in targeted.
You give your patient an anti-histamine and she asks, "which specific immune cells does this medication target?"
Antigen-specific Th1 and Th2 cells.
You give your patient a vaccine and he asks, "what specific type of immunity is a vaccine"
Artificial acquired active humoral immunity.
Which structures do viruses use to attach themselves and enter the host cells?
Attachment proteins in the capsid, or via glycoproteins embedded in the viral envelope.
Generally speaking, what is passive immunity?
B cells are not challenged by antigens. Immunological memory does not occur.
Why are enveloped viral infections typically associated with persistent infections?
Because they are more virulent. The extra protein coat makes it harder for them to be digested by enzymes.
Complement and antibodies both play a role in apoptosis. What is complement's apoptosis function?
By changing their extracellular composition, apoptotic cells acquire the capacity to bind to complement initiation molecules such as C1q and MBL.
T cell receptors only recognize antigens that combine with MCH on the surface of the cell, what is the difference between MHC class 1 and MHC class 2.
Class 1 is found on virtually all body cells while class II is found on certain cells in the immune response.
What type of virus is this?
Complex virus.
Interferon is also a "message" that activate macrophages and natural killer cells. How do they respond?
Cytokines are secreted that disrupts viral replication and make the cell more susceptible to attack by NK cells.
Where in a host cell do RNA viruses begin their synthesis?
Cytoplasm.
Name one adaptive immune cell that can trigger a foreign cell to commit apoptosis.
Cytotoxic T cells.
Which of the specific five stages of lytic replication determines whether the virus can infect our patients?
Entry
True or false. An RNA virus must go to the nucleus first, before being translated by the host cell ribosome.
False
True or false. Bacteriophages can make humans ill.
False
True or false. Like bacteriophages, animal viruses have tails or tail fibers.
False
True or false. Many current suspect disease cause hypothesis include viral and prions.
False
True or false. Once activated, complement proteins do not require any other proteins or cells in order to kill an infected cell.
False
True or false. Retroviruses have to use a lot of their own energy to reverse transcribe themselves.
False
True or false. Some viruses have ATP generating enzymes.
False
True or false. Viriods and prions are more like living cells than viruses.
False
True or false. Lytic release does not usually harm the host cell.
False.
Some viruses have a lipid bilayer, also known as the viral envelope. Where do enveloped viruses obtain their envelope?
From host cell membranes by budding. Budding occurs either at the outer cytoplasmic membrane, the nuclear membrane, or at the membranes of the Golgi apparatus.
Which specific animal viral structure is most like a bacteriophage tail fiber?
Glycoproteins and plasma membrane proteins.
Generally speaking, what do interferons do?
Group of signaling proteins made and released by host cells in response to the presence of several viruses.
What type of virus is this?
Helical virus
Which viruses play an important role in the development of cervical cancer?
Human papilloma virus (HPV).
How is lysogeny different from the lytic stage?
In the lysogeny stage, the virus stays in the host cell deactivated while in the lytic stage, the virus kills the cell and burst it open.
What is a viroid?
Infectious pieces of naked RNA Only infect plants
Natural Killer Cells (NK) are innate or adaptive responder?
Innate
You and your colleague are looking at a viral lytic phage replication cycle. You notice that the number of infective visions in a cell culture (cells in tryptic soy broth) seem to disappear over time. Where did the virions go?
Into their host cells. Then, you get a cell burst.
What role does the p53 play in mutation?
It activates genes that promote cell growth, death, and other p53 functions.
What is the function of the reverse transcriptase enzyme?
It catalyzes the transcription of retrovirus RNA into DNA.
Name one inflammation benefit.
It is the body's way of signaling the immune system to heal and repair damaged tissue, as well as defend itself against foreign invaders, such as viruses and bacteria.
Retroviruses use human cells to make a DNA copy of itself, which is then transcribed into an mRNA which is translated at the host's ribosome. What is the advantage of this process of "reverse transcribing" itself?
It makes the virus go through the "cap and splice" stage and makes it more resistant to digestive enzymes.
What is the function of destruction of large parasites by macrophage and eosinophil?
Large parasites cannot be ingested by phagocytes. So, eosinophils can attack it.
Generally speaking, what are cytokines?
Low molecular weight, soluble proteins that are produced in response to an antigen and function as chemical messengers for regulating the innate and adaptive immune systems. They are inflammatory proteins.
Name one cell and its specific inflammation function.
Macrophages
We described "two hits" that lead to oncogenesis. Briefly describe the first "hit"
Mutation in the RB1 gene.
Mention one bacteria that has become resistant to the digestive methods during phagocytosis?
Mycobacterium tuberculosis.
What is the difference between natural killer cells and cytotoxic T cells?
NK cells are activated in response to interferons or macrophage-derived cytokines. They serve to contain viral infections while the adaptive immune response generates antigen-specific cytotoxic T cells that can clear the infection.
Name one non-adaptive immune cell that can trigger a foreign cell to commit apoptosis.
Natural killer cells.
Placental transfer of antibody from mother to baby would be classified as a) Acquired active immunity b) Naturally acquired passive immunity.
Naturally acquired passive immunity.
Are there any non-parasitic viruses?
No
Are viruses cellular beings?
No
Where in a host cell do DNA viruses begin their synthesis?
Nucleus
Name one specific physical property that gives skin its protective, immune function.
Passive physical barrier.
The process by which a macrophage "tracks" down and destroys a bacteria is called?
Phagocytosis.
What type of virus is this?
Polyhedral virus.
What is the difference between primary response and secondary response of immunological memory?
Primary response occurs when an antigen comes in contact to the immune system for the first time while secondary immune response occurs after.
Genes that are involved in the normal regulation of the cell cycle and can be altered to increase probability of cancer are called?
Proto-octogens, when mutated in certain ways, become oncogenes, genes that cause a cell to become cancerous.
What makes a retrovirus different than typical RNA viruses?
RNA viruses go into the cytoplasm for translation while retroviruses reverse transcriptase to DNA first and go through the whole process of cell replication.
Name one specific chemical property that gives skin its protective, immune function.
Skin is slightly acidic.
Once a macrophage ingests a bacteria, how does that bacteria die inside the macrophage?
The bacteria becomes trapped in a phagosome, which then fuses with a lysosome. Within the phagolysosome, enzymes and toxic peroxides digest the pathogen.
How do bacteriophages invade the bacteria cell?
The bacteriophage directly injects its nucleic acid, multiplies, and finally breaks out the bacterial cell open to release new viruses.
Name one inflammation risk?
The body's inflammatory response can eventually start damaging healthy cells, tissues, and organs. Over time, this can lead to DNA damage, tissue death, and internal scarring which can cause cancer.
Generally, what happens during the inflammation response?
The damaged cells release chemicals including histamine, bradykinin, and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling.
How are lytic and lysogenic viral cycles different?
The lytic cycle leads to death of the host whereas the lysogenic cycle leads to integration of phage through the host genome.
What is phagocyte chemotaxis?
The movement of phagocytic cells in response to a chemical stimulus.
What does the host range refer to?
The range of host cells that an individual strain of virus is permissive and susceptible to.
Define metastasis
The spread of cancer cells beyond their original site.
Why are the HIV glycoproteins important to its virulence.
They allow the virus to attach to the receptor sites on the host cells and aids entry into the host's cell.
How does interferon warn a neighboring cell about an infective virus?
They are secreted by infected cells to warn their neighbors, and once stimulated, cells of the immune system secrete interferons as part of their viral surveillance.
How do perforins work?
They cause the target cell to lyse
How do natural killer cells contribute to our non-adaptive immunity?
They directly induce the death of tumor cells and virus-infected cells in the absence of specific immunization.
What do proto-oncogenes encode?
They encode proteins that control cell division
What does a neighboring cell that received an interferon do to protect itself?
They inhibit cell division. They promote or impede the differentiation of cells.
Name one specific way antiviral drugs affect viral replication.
They inhibit replication by preventing the viral load from increasing to a point where it could cause pathogenesis, allowing the body's innate immune mechanisms to neutralize the virus.
Viruses are referred to as obligate intracellular parasites because: a) Viral DNA inserts itself into host DNA. b) they reproduce and exit the cell. c) They use the host's energy to live. d) They must use the host's machinery to synthesize components required for assembly into new virus particles.
They must use the host's machinery to synthesize components required for assembly into new virus particles.
What do neutrophils do to kill bacteria?
They phagocytosize, kill, and digest bacteria and fungi. When a cell explodes and spills out its contents, it damages other cells close to it.
How do phagocytes contribute to our non-adaptive immunity?
They protect the body by ingesting harmful foreign particles, bacteria and dead or dying cells.
How specifically do natural killer cells, killl foreign or diseased cells?
They secrete IFNy and TNFa.
In their attempts to find vaccines, HIV researchers originally made drugs called interferons. What do you suppose this drug did to the cells that HIV infects.
They stopped the cells from replicating.
Generally speaking, what is active immunity?
This is when B cells encounter antigens and produce specific antibodies against them. They create memory cells.
True or false. All viruses require host enzymes for translation.
True
True or false. Complement proteins have active and inactive states.
True
True or false. Inactive complement proteins induces apoptosis.
True
True or false. Macrophages are motile.
True
True or false. Most viruses have a narrow range.
True
True or false. Our immune systems are capable of eliminating a virus, it removes its envelope and capsid.
True
True or false. T cells, B cells, antibodies, complement are components of (adaptive or innate) immunity.
True
True or false. The more hosts a virus has before it infects a human increases its virulence.
True
True or false. The only opportunity a virus has to synthesizing its proteins is inside of a cell.
True
True or false. The reason that retroviruses can direct the formation of DNA from RNA is because most retroviruses contain the enzyme, reverse transcriptase.
True
True or false. The viral envelope increases virulence.
True
True or false. Viral attachment decreases with an increase in temperature.
True
True or false. Viral budding can kill its host by preventing nutrient uptake.
True
True or false. Viruses are more chemical than biological.
True
True or false. Viruses cannot infect during their inactive states.
True
What is phagocyte margination?
When a cell engulfs a particle to form an internal compartment called a phagosome.
What is phagocyte migration?
When phagocytic cells move from one location to another when needed.
What is phagocyte diapedesis?
When resting phagocytes are activated by inflammatory mediators and produce surface receptors that increase their ability to adhere to the inner surface of capillary walls enabling them to squeeze out of the capillary and enter the tissue.
You witness a mother give birth to a new baby. You are a specialist whose job it is to get babies to nurse from their mothers. While doing so, the new mom asks, "Does my milk give my baby protection from microorganisms? What do you say to her?
Yes, it does but i'ts only temporary.
Your patient has swine flu and fortunately for them, they recover after a period of hospitalization. Before they are discharged, they ask, "Should I get a swine flu vaccine before I leave?" What do you say to them?
You do not need to. You have gained natural immunization.
Term for bacteriophages that have the ability to either cause a lytic infection or integrate their genome into the host cell chromosome after entry into the host cell. a) Lysogenic phage. b) Virulent phage. c) Transposable phage. d) Cytopathic phage.
a) Lysogenic phage.
What is the most common way for non-enveloped viruses to enter animal cells? a) The virion fuses itself to the cell membrane. b) The virion directly injects its nucleic acid. c) Endocytosis of the virion. d) Through lysis of the cell. e) Via a hole in the cell membrane.
a) The virion fuses itself to the cell membrane.
What is a prion?
an infectious protein that are misfolded with the ability to transmit their misfolded shape onto normal variants of the same protein.
Substances that are recognized by the body as foreign and provoke an immune response are called? a) Antibodies. b) Antigens. c) Cytokines. d) White blood cells.
b) Antigens.
Acquired Immune Deficiency Syndrome (AIDS) is caused by a retrovirus. Which of the following best represents the genetic information flow used by retroviruses? a) DNA - mRNA - protein. b) DNA - protein c) RNA - DNA - mRNA - protein d) RNA - protein.
c) RNA - DNA - mRNA - protein.
What is opsonization?
complement proteins "flag" the microorganism for phagocytosis.
Which Domain contains viruses? a) Bacteria. b) Archaea. c) Eukarya. d) It depends upon their host. e) They are not classified at the domain level.
e) They are not classified at the domain level.
What is the viral envelope made of?
phospholipid bilayer and proteins and viral glycoproteins on the surface of then envelope to serve and identify and bind to receptor sites.
What is apoptosis?
programmed cell death
Once activated, what does complement do to a targeted cell?
promotes inflammation through recruiting both the innate and adaptive immune cells, and attacks the pathogen's cell membrane itself.
Define neoplasia
the formation or presence of a new, abnormal growth of tissue.
What are oncoviruses?
viruses that cause cancer