BIO 205 Exam 3

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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


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