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MICR 221 - Final Biology Exam Questions with Answers Latest Update 2024 Test.
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MICR 221 - Final Biology ExamQuestions with Answers Latest Update
2024 Test
2 ways that viruses can be driving forces in host evolution - Correct
Answers - can be selective forces in a population
- can provide direct or indirect advantages to host survival
example of virus as a driving force: Coterie congregate polydnavirus and
mandala seta - Correct Answers contusion congregate = parasitic wasp
whose genome encodes a polydnavirus (in ovaries)
- wasp lands on mandala seta (caterpillar) and injects both the virus and its
eggs. The virus will suppress the immune system of the caterpillar, allowing
the eggs to develop inside.
example of virus as a driving force: Spodoptera litura - Correct Answers
Female noctuid moth produces an RNA virus that kills male embryos
- advantageous to the population because females have higher
reproductive value than males
example of virus as a driving force: Human endogenous retroviruses
(HERVs) - Correct Answers - retroviruses are converted from sera to
dada and integrated into human genome
- this has been shown to occur throughout history as human genome
contains 8% HERVs
- fusion mediating proteins of retroviruses are shown to manifest from
HERVs to mediate the process of the fusion of the trophoblastic and
syntiotrophoblast to form the placenta
Why is it necessary for viruses to reach a balance in their host population?
- Correct Answers - Viruses can't kill host 100% of the time, or there will
be no host to persist in
- Host population can't clear virus completely, or there will be no reservoir
for the virus to persist
,How has the study of virus replication enhanced our study of molecular cell
biology - Correct Answers - virus/host interactions are molecular
negotiations that must be understood in order to defend ourselves against
viruses
- we can exploit the properties of viruses (specificity, lethality etc) for
practical use through the development of viruses as therapeutic agents
Virus - Correct Answers submicroscopic, obligate intracellular parasites
that are assembled from pre-formed components and do not grow or
undergo division
- genomes do not encode for energy production, ribosomes, trans, lipid
membrane synthesis
Mimi virus - Correct Answers "mimicking microbe"
Blurs boundary between bacteria and virus
- larger genome than all other viruses that encodes for protein translation,
DNA repair, lipid metabolism
- has its own virus particles inside it (sputnik)
True or False: viruses can contain viruses within them - Correct Answers
True
example, Mimi virus contains sputnik visions
5 part strategy of - Correct Answers 1. They build small particles to
contain their nucleic acid genome
2. They have small genomes: usually less than 100 genes, often less than
10
3. They have an infectious cycle: particles bind to cells; enter; release
genome; decode genome; replicate genome; build particles; exit cells
4. They establish a relationship with their host, ranging from benign to
lethal
5. They overcome host defenses with comparative ease
size of viruses - Correct Answers generally larger than ribosomes and
proteins, yet smaller than bacteria
Plaque assay - Correct Answers Used to quantify viruses
- each plaque produced represents a single "successful" infection,
expressed as PFU/volume
,- Cannot tell you the number of virus particles, just the number of infectious
viruses
Chicken egg propagation of viruses - Correct Answers 1931 - Woodruff
and Good pasture
- used embrocated chicken eggs as a host for viruses; different inoculation
locations; amniotic sac, yolk sac, allantois
- different viruses are inoculated in different locations
Cell culture system propagations - Correct Answers 1948-1955
- development of cell culture systems for studying virus replication
- growing a layer of cells then adding virus to observe differences
Fluorescent visualization of virus replication - Correct Answers fluorescent
proteins from corals and jelly fish have been isolated and used to visualize
the spread of viruses between cells
Why must a virus build a particle to protect it - Correct Answers Must
protect their genomes from proteolysis and nucleolytic enzymes, extremes
of pH and temperature, various forms. of natural radiation and shearing by
mechanical forces
Considerations for the virus particle - Correct Answers - information
necessary to specify the structural proteins must not exhaust the coding
capacity of the genome
- particle must be stable enough to protect the nucleic acid, but also
mediate attachment to the host cell
Capsid - Correct Answers The protein shell that encloses and protects the
viral nucleic acid
- selective genome delivery device - has selective incorporation of the viral
genome into the capsid
- 2 general mechanisms: helical capsids and capsids with icosahedral
symmetry
Cashmere - Correct Answers The morphological unit of the icosahedral
capsid
Core - Correct Answers the internal part of the virus particle that consists
of the nucleic acid and closely associated proteins
, nucleocapsid - Correct Answers the structure composed of the capsid
containing the nucleic acid or core
naked virus - Correct Answers virus without an envelope
envelope - Correct Answers the viral membrane consisting of a lipid
bilayer containing spike proteins
spike proteins - Correct Answers viral glycoproteins that project from the
envelope
2 ways of packaging capsids - Correct Answers helical capsids and
capsids with icosahedral symmetry
helical capsids prevalence - Correct Answers found in many plant viruses
and bacteriophages
- only found in animals as enveloped RNA genomes
helical capsid structure - Correct Answers Formed by a planar net for
identical protein subunits (promoters)
- capsids are open structures, ends of rod are not sealed
- dimensions of nucleocapsids vary between different types of viruses
- flexible or rigid
icosahedron - Correct Answers 20 sided geometrical structure that forms
a sphere
- composed of a triangular building blocks
- has five hold (faces), threefold (vertices) and twofold (edges) of symmetry
capsids with ices - Correct Answers building blocks (triangles) can be
formed by the virus using 3 of the same promoter that have different amino
interactions
- different viruses are different sizes, thus their icosahedrons will have
different numbers of proteins
retrovirus capsid - Correct Answers - neither helical or icosahedral
- elongated sphere of pen tamers, capsizers and heaters
poxvirus capsid - Correct Answers - neither helical or icosahedral
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