BIO 205 Exam 3
Globally, about what % of human cancers are associated with viruses?
12%
What percent of infectious diseases in humans are zoonotic infections?
70%
Lytic cycle
A type of viral (phage) replication cycle resulting in the release of new phages by lysis (and death) of the host cell - cell bursts open letting viruses out
Some viruses have an envelope surrounding the nucleocapsid which is what?
Acquired from the host cell when the virus buds off from the host cell
There are 3 ways (mechanisms) by which oncogenic viruses cause tumors. During which of the following mechanism, the virus infects a normal human cell and the viral oncogene integrates and expresses the viral oncogene in the host cells converting the normal cell into a tumorous or cancerous cell? Gene activation Oncogene activity All choices are correct Gene suppression
All choices are correct
What is budding?
Asexual reproduction in unicellular fungi.
Most fungi grow well at what temperature?
At ambient (room) temperature of 23 to 25 degrees Celsius
What are viruses that infect bacterial cells called?
Bacteriophages
How do we see viruses?
By looking at the damage they cause to the host cell = cytopathic effect
It is believed that smallpox and measles viruses evolved from which of the following animals?
Cattle viruses
According to which hypothesis for the origins of viruses, they were derived from subcellular components (DNA and RNA) and functional assemblies of macromolecules that escaped from cellular forms of life due to their ability to replicate separately in host cells?
Cellular origins hypothesis
Fungal cells have a cell wall made up of ______.
Chitin
Fungal cells have all of the following except
Chlorophyll
According to which hypothesis for the origins of viruses, they coevolved with cellular organisms from the self-replicating molecules which were present in the primitive prebiotic earth?
Coevolution hypothesis
Where are spike proteins present?
Either on the capsid (on non-enveloped viruses) or on the viral envelope. The spike proteins are specific for the receptors on the host cell
What do viruses use to replicate inside a host cell?
Enzymes and metabolites of host cells
A malignant tumor is a cluster of cells or a local tumor surrounded with fibrous tissue called a capsule. True False
False
It is very easy to study the origins of viruses because viruses are often present in fossil records. True False
False
Name some characteristics of lysogenic cycle
GN lysogenic cycle of replication the viruses genome integrate w/ the host cell chromosome. They remain in the host cell in a latent state
All viruses have which characteristics?
Genome Protein coat called a capsid nucleocapsid
Dysbiosis (imbalance) in the bacterial and mycobiome communities can make an individual susceptible to all of following diseases except ______________.
HIV
Which of the following virus is an oncogenic (tumor-causing) virus which causes cervical and uterine cancer in woman?
Human papillomavirus (HPV)
LUCA is an acronym for what?
Last unknown common ancestors
All of the following are examples of newly emerging viruses except
Measles Virus
A mass of intertwined filaments (or hyphae) of fungi is called a _____.
Mycelium
Fungi which live in a symbiotic (mutualistic) beneficial relationship in and around plant roots are called _____________.
Mycorrhizae
Is there fossil record of viruses?
No.
Viruses are acellular - what does that mean?
Not self replicative - don't grow
Regressive evolution hypothesis
One of the first biologists to suggest devolution was Ray Lankester, he explored the possibility that evolution by natural selection may in some cases lead to devolution, an example he studied was the regressions in the life cycle of sea squirts.
Based on Stanley Prusiner's research, prions are made up of
Proteins only
Fungi include all of the following organisms except ____________.
Protists
Which of the following is a cause of zoonotic diseases in humans?
Proximity of human populations to wild and domestic animals due to an increase in human population
What led to the emergence of H1N1 flu virus in 2009?
Reassortment of genomes of avian flu virus, human flu virus and swine flu virus human
According to which hypothesis for the origins of viruses, they are thought to be degenerate life forms which lost all the functions of a free-living cellular form of life and retained only the components needed for infection and replication in living host cells as intracellular parasites?
Regressive evolution hypothesis
The fungi which feed on dead plants and animals by secreting enzyme to break down the organic molecules in dead decaying matter into simpler molecules are called ____.
Saprobes
When conditions become harsh or unfavorable what happens to the viral genome?
The viral genome excises from the host chromosome and lytic cycle occurs. These are called temperature viruses
In bacteriophage there is no uncoating true false
True
Normal prions are present in normal brain and nerve tissues and play important roles in neuron protection and learning during infant development. True False
True
Scrapie in sheep and goat is a neurological degenerative disease similar to mad cow disease. True False
True
Some fungi can be filamentous at ambient temperature of 23-25 degrees Celsius and limited nutrients but these fungi can transform to a pathogenic unicellular yeast-like form at human body temperature of 37 degrees Celsius. These fungi are called dimorphic fungi. True False
True
The study of fungi is called mycology. true false
True
Viruses are among the oldest life forms on earth. True False
True
What is pro-virus
Viral genome integrated w. eukaryote cell chromosome
Name some characteristics of lytic cycle
Virulent viruses Replicate and cause lysis of the host cell
What are the most abundant microbes on earth?
Viruses
In 1986, the cattle in Great Britain died of a mysterious illness called "mad cow disease". Cows suffering from mad cow disease had all of the following symptoms except _____.
Well-coordinated and calm behavior
When an abnormal misfolded prion binds to a normal prion in nervous tissue, the normal prion becomes misfolded and abnormal. This continues like a chain reaction leading to more misfolded prions which form insoluble protein fibers and aggregate forming sponge-like holes in the nervous tissues causing transmissible spongiform encephalopathies (TSEs) disease.
When an abnormal misfolded prion binds to a normal prion in nervous tissue, the normal prion becomes misfolded and abnormal. This continues like a chain reaction leading to more misfolded prions which form insoluble protein fibers and aggregate forming sponge-like holes in the nervous tissues causing transmissible spongiform encephalopathies (TSEs) disease.
What is serology?
When you look for antibodies
Can viruses mutate and evolve?
Yes
What is retrovirus
any of a group of RNA viruses which insert a DNA copy of their genome into the host cell in order to replicate, e.g. HIV.
What are the steps of virus replication
attachment, penetration, uncoating, replication, assembly, and virion release
Unicellular yeasts which can thrive either in presence or absence of oxygen are ________________fungi which can do fermentation in the absence of oxygen.
facultative
Fungi are prokaryotic organisms lack that membrane-enclosed organelles like nucleus, mitochondria and endomembrane systems. true false
false
The oral mycobiome of HIV infected people is exactly same as the mycobiome in uninfected individuals. true false
false
Co-evoloution
reciprocal evolutionary changes brought about by interactions between species
What is the optimal pH for fungal growth?
slightly acidic pH between 5-6
What is prophage?
the genetic material of a bacteriophage, incorporated into the genome of a bacterium and able to produce phages if specifically activated.
All the fungi present on and in a human body make up the human mycobiome. true false
true
Cellular Origins Hypothesis
viruses come from small primordial cells (not necessarily primitive), which lost their cellular elements in the course of evolution
