Bio Unit 4 Module 1
Some but not all viruses have what which surrounds the entire capsid
lipid membrane, or envelope,
Historically, biologists have not classified viruses as what?
living organisms
What are RNA virsues more prone to?
mutations
The capsid may have proteins attached to it, such as tail fibers or spikes, that assist what?
the virus in attaching to the target cell
How are Viruses are different
their genome may use either DNA or RNA as their genetic material.
Proteins often have complex, three-dimensional shapes, and in the case of the capsid proteins?
these complex shapes allow the virus to target specific molecules on the surface of the target cell.
Viruses are typically considered nonliving bc?
they cannot reproduce by themselves without a host
Viruses that possess an outer envelope leave by endocytosis in Release in lytic cycle. As they exit, what happens?
they often create an envelope about themselves by acquiring pieces of the host cell's plasma membrane.
Viruses do possess the ability to change over time, or evolve. In the case of the influenza virus?
they present an excellent example of the importance of understanding the impact of evolutionary change on our lives.
Often, viruses are picked up on the hands and introduced to the body when we touch our faces or mouth, or handle food From here, what happens?
they quickly enter into the respiratory system and travel down the pharynx into the trachea and lungs
Viruses do possess the ability to do what?
to change over time, or evolve
The genetic material of a virus contains the instructions needed to do what?
to manufacture the proteins that compose the capsid surrounding the virus and spikes
What is DNA surrounded by?
proteinaceous capsid
The influenza A virus, which uses RNA as its genetic material, contains how mant genes?
11
How many genes do humans have?
19,000
The influenza virus are very specific in what?
the types of cells they interact with.
Scientists have estimated that almost _% of the human genome is actually viral in nature, and thus evidence of how active the lysogenic cycle has been in our evolutionary history.
8%
Some viruses, such as the as what possess an envelope that surrounds a capsid
9nfluenza virus
How are Bacterial and viral infections are treated differently
Antibiotics helping against bacteria, but not viruses
What is step 1 of The Lysogenic Cycle?
As the host cell divides, the viral DNA is replicated along with the host cell DNA, thus creating new cells that contain the virus.
What are giant viruses?
As their name suggests, these viruses are much larger than a typical virus [which may be as small as 10 micrometers in size] with some almost half the size of bacteria
What does the envelope of a virus assist in?
Assists in the attachment and entry of virus into the host
Explain Biosynthesis lytic cycle?
At this point, the virus hijacks the host cell's machinery to manufacture new capsid proteins and copies of its genetic material. Energy and materials for these processes are all provided by the host cell
What are the 5 stages of the The Lytic Cycle?
Attachment: viral capsid combines with host cell receptor Penetration: Viral DNA enters host cell Biosynthesis: Viral component are synthesized Maturation/assembly: Viral components are assembled Release: New viruses leave the host cell
What may cell do between pentration and biosyntheis
Cell enter lysogenic cycle at this point as the viral DNA integrates into host cell
As far as we know, all living organisms use what?
DNA as their genetic material.
Viruses are made up of _____ inside a protein cell called a capsid
DNA or RNA genome
What is step 7 of Life Cycle of RNA Viruses
During maturation, viral particles are assembled into new viruses and then, release occurs as viral particles are released outside of the cell.
How are viruses different from bacteria?
Even though they both can make us sick, they are very different at the biological level Bacteria: small and single cell organisms that do not depend on a host cell to reproduce Bacterial and viral infections are treated differently - Antibiotics helping against bacteria, but not viruses
What is an example of Viruses are not capable of processing energy or materials, instead rely on a host cell for those processes?
For example, the influenza virus requires epithelial cells that line our respiratory system in order to reproduce
Example of the Lysogenic cycle is?
HIV
What is an example of an RNA virus
HIV
What do RNA virsues include?
HIV and influenza
RNA genetic material in humans example
HIV, influenza
What is important to note about the envelope in accordance to the plasma membrane?
It does not function the same as the plasma membrane w regulation and movement of materials in and out the cell
What are the size of viruses?
Very small, smaller than most living things
What is Release in the lytic cycle?
New viruses leave the host cell
What is step 5 of Life Cycle of RNA Viruses
Next, replication occurs as the viral genetic material is duplicated
What is Penetration in the lytic cycle?
Viral DNA enters host cell
What is step 1 of how influenza effects the body?
Once in the respiratory tract, the H spikes of the influenza A virus identify host epithelial cells by detecting the presence of specific glycoproteins on the surface of the cells.
What is step 4 of how influenza effects the body?
Once inside the cell, the virus not only hijacks the cellular machinery to make new viruses but also produces proteins that interfere with the normal function of the epithelial cell.
What is step 6 of Life Cycle of RNA Viruses
Once that is complete, biosynthesis of new viral proteins can occur.
Explain penetration in the lytic cycle?
Once the virus has identified the host, its genetic material enters the cell.
Influenza has 2 types of spikes, what do they do?
One type fuses with the host cell membrane, allowing the virus particle to enter the cell Help the newly formed virus particle to bud out from the host cell membrane Also play a role in seeing how the virus evolves over time
Biologists use five characteristics to determine if something is considered alive or not. These include the ability to?
Process energy and materials Maintain an internal environment Reproduce Adapt to changing environmental conditions
The influenza A virus, which uses ____ as its genetic material, contains just 11 genes.
RNA
What is the difference between RNA and DNA Viruses
RNA viruses - Contains ribonucleic acids as genetic material - Surrounded by a proteinaceous capsid - Incorporates its genetic material into the host cell - Requires reverse transcriptase to synthesize proteins - Includes HIV and influenza - More prone to mutations DNA viruses - Contains deoxyribonucleic acid as genetic material - Surrounded by a proteinaceous capsid - Incorporates its genetic material into the host cell - Includes small pox, chicken pox, and herpes
What is step 1 of Life Cycle of RNA Viruses
RNA viruses binds to the plasma membrane of the host cell during attachment,
What is Biosynthesis in the lytic cycle?
Viral component are synthesized
What is step 3+4 of Life Cycle of RNA Viruses
Reverse transcription is the process by which viral RNA is converted into DNA with the aid of the reverse transcriptase enzyme.
What is evidence of how active the lysogenic cycle has been in our evolutionary history.
Scientists have estimated that almost 8% of the human genome is actually viral in nature,
What are the 2 major steps of The Lysogenic Cycle?
Step 1: As the host cell divides, the viral DNA is replicated along with the host cell DNA, thus creating new cells that contain the virus. Step 2: The virus remains latent until some environmental factor signals it to re enter the lytic cycle and begin the process of biosynthesis and maturation
What are the Steps how influenza effects the body?
Step 1: Once in the respiratory tract, the H spikes of the influenza A virus identify host epithelial cells by detecting the presence of specific glycoproteins on the surface of the cells. Step 2: The N spikes then act to break down the membrane and initiate the entry of the virus into the target cell. - The initial infection may occur at any point along the respiratory tract, from the nasal cavity to the lungs. Step 3: The replication cycle of the influenza virus begins almost immediately, and the production of new viruses can start within just a few hours. Step 4: Once inside the cell, the virus not only hijacks the cellular machinery to make new viruses but also produces proteins that interfere with the normal function of the epithelial cell.
What are the steps of Life Cycle of RNA Viruses
Step 1: RNA viruses binds to the plasma membrane of the host cell during attachment, Step 2: enters the cell during fusion and entry, and then become uncoated once in the cell. Step 3+4: Reverse transcription is the process by which viral RNA is converted into DNA with the aid of the reverse transcriptase enzyme. Step 5: Next, replication occurs as the viral genetic material is duplicated Step 6: Once that is complete, biosynthesis of new viral proteins can occur. Step 7: During maturation, viral particles are assembled into new viruses and then, release occurs as viral particles are released outside of the cell.
How do viruses work with a host?
Take over host cell and uses its resources and using it as a virus factory
What is step 2 of how influenza effects the body?
The N spikes then act to break down the membrane and initiate the entry of the virus into the target cell. - The initial infection may occur at any point along the respiratory tract, from the nasal cavity to the lungs.
Once the virus has entered the target cell, there are two pathways; or cycles, it can follow. What are they?
The lytic cycle The lysogenic cycle
What is Maturation/assembly in the lytic cycle?
Viral components are assembled
What is step 3 of how influenza effects the body?
The replication cycle of the influenza virus begins almost immediately, and the production of new viruses can start within just a few hours.
Explain Attachment in the lytic cycle?
The structure of the proteins in the capsid allows it to recognize and target specific cells for infection
What is step 2 of The Lysogenic Cycle?
The virus remains latent until some environmental factor signals it to re enter the lytic cycle and begin the process of biosynthesis and maturation
Viruses have some important features in cell based life, what are they?
They have nucleic acid genomes used in the cells of all living organisms Viruses have genetic mutations and can evolve
How does the virus must convert it's RNA into DNA?
This is done by an enzyme supplied by the virus called reverse transcriptase
Explain Release in lytic cycle?
This is possible by either causing the host cell to burst (called lysis) or by exiting through the plasma membrane (exocytosis). - Viruses that possess an outer envelope leave by endocytosis. - As they exit, they often create an envelope about themselves by acquiring pieces of the host cell's plasma membrane.
What is the problem with converting it's RNA into DNA by an enzyme supplied by the virus called reverse transcriptase
Unfortunately, the reverse transcripstae enzyme is not always efficient in copying the RNA into DNA, and it introduces mistakes, or mutations that cause variations in the new viruses
What is still being debated about giant viruses?
Whether these viruses were actually at one time cells, which became parasitic or lost some internal functions, or whether these viruses accumulated the protein making machinery from bacteria
The number of genes in a virus is often only what?
a fraction of what is found in living organisms.
Viruses need what in order to replicate
a host cell
Viruses are not capable of processing energy or materials, instead rely on what?
a host cell for those processes
Historically, biologists have not classified viruses as living organisms. This idea is being challenged by the discovery of what?
a new group of viruses, called the giant viruses
What do many scientists suggest about the tree of life?
a number of scientists are suggesting that the tree of life be reorganized to include the viruses as living organisms.
What is Capsid
a protein coat that surrounds the genetic material.
What are RNA virsues surronded by
a proteinaceous capsid
What is bacteriophage?
a type of virus that infects bacteria
In the lytic cycle, viral reproduction begins when?
almost immediately after the virus enters the host cell
Cytokines act as what?
an alarm to the organ systems of the body, alerting them that a pathogen is present.
Some viruses, such as the influenza virus possess what
an envelope that surrounds a capsid
What are viruses?
are obligate intracellular parasites of cells They have to have a in order to live within the cell
how many genes do rice plants have
as many as 32,000 genes.
The capsid may have proteins attached to it, such what, that assist the virus in attaching to the target cell
as tail fibers or spikes
The N spikes then act to break down the membrane and initiate the entry of the virus into the target cell. - The initial infection may occur?
at any point along the respiratory tract, from the nasal cavity to the lungs.
Why do cells play a very important role in regulating the activities of the body?
because any substances that enter or leave the body must pass through them before entering the blood stream and other body tissues.
When may Cell enter the lysogenic cycle at this point as the viral DNA integrates into host cell
between pentration and biosyntheis
influenza effect the muscular system cytokine action
breakdown of muscle fibers and accumulation of fluid
How does influenza infect?
by convincing the host cell to engulf the entire virus (a process called endocytosis). once in the cell the virus releases its genetic material into the host cell.
Viruses that possess an outer envelope leave by what in Release in lytic cycle?
by endocytosis.
Once this molecule is identified, the influenza virus can do what?
can begin to integrate into the host cell
Viruses are made up of DNA or RNA genome inside a protein cell called a?
capsid
Viruses do not have what?
cells
Most other flu symptoms are not the direct result of the influenza virus, but are due to the body's response to the virus with activation of the immune system. This is due primarily to what?
chemical signals released by the immune system in response to an infection.
influenza effect the integumentary system symptoms
chills
Proteins often have ?, and in the case of the capsid proteins, these complex shapes allow the virus to target specific molecules on the surface of the target cell.
complex, three-dimensional shape
The number of genes in a virus varies how?
considerably between species.
What is step 2 of Life Cycle of RNA Viruses
enters the cell during fusion and entry, and then become uncoated once in the cell.
In RNA Viruses before the proteins for new viruses can be manufactured during the biosynthesis stage what must happen?
convert it's RNA into DNA
What is hypothesizd about giant viruses?
could have at one time been parasitic cells that lost some internal functions OR could have accumulated this ability from bacteria.
The white blood cells of the immune system release proteins called?
cytokines
What do DNA contain as genetic material?
deoxyribonucleic acid
The purpose of a virus is to do what?
find a host cell, then hijack the metabolic machinery of that cell to produce more copies of itself
What are epithelial cells?
form the boundary between the tissues of our bodies and internal environments, such as the respiratory and digestive track
Within the DNA of an orgamsims are set of instructions, called?
genes
Despite their differences, all viruses have the following two components?
genetic material capsid
Viruses have a similar structure, but different what
genetic materials
The sum of all the genes in an organism (or species) is commonly called?
genome
These proteins, also called spikes, recognize ______ on the surface of host cells.
glycoproteins
Because epithelial cells are involved in regulating the movement of materials into and out of the tissues of the body, any disruption of this function will have what
have an adverse effect on the tissue or organ—in this case, the lungs. - One of the first reactions to this is accumulation of fluid in the lungs.
influenza effect the nervous system symptoms
headache, fever
Studying the envelope of these viruses are protein spikes which do what?
help the virus invade host cells
Influenza viruses reproduce by what?
hijacking the machinery of our body
The genetic material of a virus contains the instructions needed to manufacture the proteins that compose the capsid surrounding the virus and spikes. These proteins play an important role in what?
identifying the type of host cell for the virus.
What is the lytic cycle?
immediately begins using the resources of the host cell to manufacture new viruses
As the epithelial cells lose their function, they may also undergo apoptosis, or programmed cell death. When this occurs, it may cause what?
inflammation of the tissue, which in turn activates the immune system.
In penetration Once the virus has identified the host, its genetic material enters the cell. This can occur by what?
injecting the genetic material directly into the host cell (leaving the capsid outside) by convincing the host cell to engulf the entire virus (a process called endocytosis).
At this point, the virus is able to _____ with the host cell.
integrate
What is the The lysogenic cycle
integrate directly into the host cell genome and delay its own reproduction until a later time
In the lysogenic cycle, following penetration into the cell, the viral DNA does what?
integrates into the host cell's DNA.
How are epithelial cells arranged?
into a thin layer of tissue, called epithelium, that is often only one cell-layer thick.
In the lysogenic cycle, reproduction?
is delayed and the viral DNA integrates into the host cell genome.
What do RNA virsues incorporate
its genetic material into the host cell
What does DNA incorporate?
its genetic material into the host cell
influenza effect the muscular system symptoms
joints and aches
What are viruses bascially?
just packages of nucleic acids and proteins
influenza effect the digestive system symptoms
loss of appetite, nausea, vomitting
What is genetic material?
may be in the form of DNA or RNA, contains small number of genes in comparison to a cell
What are the structurs of the respiratory system?
nose, pharynx, larynx, trachea, bronchi and lungs
By understanding how viruses reproduce, we can better appreciate what?
not only how they evolve, and why we need annual vaccinations, but also how scientists are developing treatments to prevent some of the diseases that viruses cause.
This specificity is the function of the proteins located where?
on the capsid of the virus
How are viruses picked up?
on the hands and introduced to the body when we touch our faces or mouth, or handle food
cells play a very important role in regulating the activities of the body, because any substances that enter or leave the body must pass through them before entering the blood stream and other body tissues. Influenza disrupts these functions, which causes what?
or many flu symptoms.
Proteins often have complex, three-dimensional shapes, and in the case of the capsid proteins, these complex shapes allow the virus to target specific molecules on the surface of the target cell. These molecules may be what?
other proteins, receptors on the surface of the cell, or other molecules integrated into the membrane of the host cell.
Influenza virus interacts with our respiratory system and indirectly causes what
other symptoms associated with the flu
influenza effect the nervous system cytokine action
presence of cytokines tells the hypothalumus in the brain to increase body temp
It is the ____ that are located on the surface of the virus capsid that determine which cells the virus infects.
proteins
The capsid may have _____ attached to it, such as tail fibers or spikes, that assist the virus in attaching to the target cell
proteins
These ______, also called spikes, recognize glycoproteins on the surface of host cells.
proteins
influenza effect the digestive system cytokine action
reduces action of appeptite centers in brain
Influenza virus interacts with our _____ system and indirectly causes other symptoms associated with the flu
respiratory
influenza effect the integumentary system cytokine action
restriction of blood vessels in the skin to conserve heat
What do RNA virsues require?
reverse transcriptase to synthesize proteins
What do RNA virsues contain as genetic material
ribonucleic acids
Unlike the lytic cycle, the virus remains what?
s inactive or latent
How do virues vary?
shape and in the types of cells they infect
What is bacteria?
small and single cell organisms that do not depend on a host cell to reproduce
What does DNA include?
small pox, chicken pox, and herpes
DNA genetic material in humans example
smallpox, chicken pox, herpes
Viruses are ____ in the cell types that they infect.
specific
What is interesting about giant viruses?
that some of them possess the ability to manufacture their own proteins, a characteristic that was traditionally reserved for organisms classified alive
Most other flu symptoms are not the direct result of the influenza virus, but are due to?
the body's response to the virus with activation of the immune system.
The primary targets of the influenza virus are what?
the epithelial cells lining the respiratory system
The respiratory system is responsible for what?
the exchange of gases with the external environment.
The HIV virus is an example of an RNA virus This presents a problem for the virus, because why?
the hosts cell's protein synthesis processes require DNA as the starting template
Influenza viruses enter the respiratory system through either?
the mouth or the nose
What is the envelope of a virus?
the remininants of the plasma membrane of the host cell
Most viruses are very specific in what?
the types of cells they infect
As the epithelial cells lose their function, they may also do what?
undergo apoptosis, or programmed cell death.
Viruses, such as influenza viruses, are amazingly efficient in what?
using the cells of our bodies as biological factories to produce millions of new viruses at an amazing rate
Scientists have estimated that almost 8% of the human genome is actually ____ in nature, and thus evidence of how active the lysogenic cycle has been in our evolutionary history.
viral
What is attachment in the lytic cycle?
viral capsid combines with host cell receptor
What is a. Tiny infectious particle that can reproduce only by infecting a host cell
virus
The ____ blood cells of the immune system release proteins called cytokines
white
