Biology - Unit II Module 1 and 2
When are strains of influenza chosen for vaccine production in the Southern hemisphere?
September prior to the start of flu season
If a favorable mutation increases the ability of an individual to reproduce then natural selection would
favor this variation
The quadrivalent influenza vaccine contains
four different influenza strains including B/Phuket/3073/2013 (Yamagata lineage) virus
The trivalent influenza vaccine contains
three different strains of influenza, which are chosen specifically each year.
The primary target of the influenza virus is the
epithelial cells lining the respiratory system.
The scientific definition of ______ refers to changes in a species or population over time.
evolution
A comparison of genetic and biochemical similarities can indicate what?
evolutionary relationships
Mammalian Cell-based Method
-Cells are placed in mammalian cell cultures, extracted, killed, and remaining virus particles are used to produce vaccines -Production is egg free
describe how an animal virus may evolve into a strain that is harmful to humans.
Certain types of influenza virus originate in an animal host, like a bird. The avian influenza virus may typically infect and transmit the virus among one animal species at a time. In some instances, an intermediate host, like a pig, allows for the exchange of genetic material between two different strains of the influenza virus: an avian influenza strain and a human virus strain. The exchange of genetic material allows the influenza virus to evolve into a new form. The virus can now be transmitted to a new host, such as humans, and spread easily from person to person causing a flu outbreak.
Integumentary: Cytokine Action
Restriction of blood vessels in the skin to conserve heat
Thomas Malthus
Stated that populations sometimes increase at rates faster than their food supply can increase, thus creating competition
During which viral life cycle does viral reproduction begin almost immediately once the virus has entered the host cell?
The lytic cycle
the general process of how viruses reproduce?
Viruses use the machinery of their host cell to make copies of themselves.
Which attributed to the outbreak of the Spanish flu in 1918?
a new variant of the influenza virus
During the process of choosing strains for the annual influenza vaccine, which of the following characteristics is most likely to qualify a strain to be included?
a strain that has a high potential for causing global pandemic
The importance of transitional fossils is that they
demonstrate relationships between two groups of organisms.
What is the primary target of the influenza virus?
epithelial cells
The process of natural selection
favors some mutations, when they increase fitness
In the northern hemisphere, influenza strains are chosen to produce the vaccinations for the following flu season. when?
in February of each year.
genetic material
is the comparison of genetic and biochemical similarities to indicate evolutionary relationships.
Similarities between Antigenic Drift and Shift
-Changes are noted on the surface spikes H and N of the Influenza virus -results in the virus evading the immune system
evidence of natural selection that Darwin observed aboard the Beagle
-Collecting fossilized remains of extinct animals along the west coast of South America challenged Darwin's idea that the Earth was young. -In regard to biogeography, Darwin discovered similar environments and animals with similar appearances in South America and Europe. -Darwin noted that unique island finch species are descendants from the mainland species that have developed adaptations to survive on the island's food source.
Quadrivalent Vaccine
-Contains two A viruses -Virus particles are inactivated and not capable of reproducing -Contains different strains of four viruses -Contains two types of Influenza B virus
Individuals Vary in Their Traits
-Heritable traits such as physical characteristics, physiology, and behavior very within a population
Antigenic Drift only
-Mutation of the virus itself -Small changes to the genetic makeup of influenza strains -After the flu strain mutates, the immune system may recognize the virus but at a reduced level of efficiency -Makes the annual flu vaccine ineffective
Body system: Integumentary system
Chills
Which molecules contain instructions for specific traits?
DNA and RNA
An influenza A virus is able to identify a host cell because of its
H Spikes
characteristics of influenza viruses
RNA and Capsid
Influenza is a(n) ______ virus surrounded by ______.
RNA; a capsid and an envelope
Characteristics of living things present in viruses
- Ability to change over time or evolve -Contain genetic material
Characteristics of living things NOT present in viruses
- Capable of processing energy or materials -Maintain an internal environment -Respond to stimuli from the environment -Contain cell machinery to replicate their genetic material: DNA or RNA
Recombinant Method
-Production is egg free -The most recent way in which flu vaccines are made -Requires the shortest development time to create a flu vaccine -Small portions of the influenza virus genome are inserted into a virus that infects insect cells, cultured, and extracted to make vaccines
Identifying the target cells of influenza
-Proteins located on the capsid of the virus allow the virus to attach to molecules on the surface of a host cell. -The capsid proteins of a virus may attach to protein receptors on the surface of the host cell. -Upon identification of a specific protein molecule on the surface of the host cell, the virus can integrate into the host cell.
Characteristic of RNA
-Single stranded -not used as the genetic material of any known living thing -nitrogen bases are U,A,C, and G
Body System: Digestive Symptoms
Loss of appetite
Antigenic shift
occurs when two different influenza viruses infect the same host cell, and a new form of the virus is manufactured.
Mutations represents what?
represent the source of genetic variation in a population
The genes of a living thing contain
the information needed to produce proteins and RNA.
Body System: Muscular Symptoms
Joint and muscle aches
Does natural selection cause mutations?
NOOO
Stabilizing Selection
- Selection favors the most common form of variant for the trait -Selection occurs against the extreme variants -The average individuals are most adapted to the environment -The population distribution narrows toward the average
Indirect effects of influenza virus on body systems
-Digestive system: Loss of appetite -Muscular System: Joint and muscle aches -Nervous system: Headache and fever -Integumentary system: Chills
criteria used to choose influenza strains for annual vaccines
Ability to produce an effective vaccine against the strain A strain's potential to cause a worldwide pandemic
describe how evidence from genetic material supports the theory of evolution
All living organisms share the type of genetic material used to store information and the same basic process of gene expression. These shared features suggest that all living things are descended from a common ancestor. When comparing genetic and biochemical similarities between species, the more similar the information is between two species, such as the nucleotide sequences of a gene, the closer their evolutionary relationship. Why? The source of variation is mutation, and for two organisms that are closely related, there is less time for changes to occur in genetic information for the trait than for organisms that are not closely related. These sequences of genetic variation may also be used to determine evolutionary history of the organism by tracing the trait back to its shared evolutionary ancestry.
Physical characteristic of the influenza virus
An RNA virus enclosed in a spherical capsid surrounded by an envelope with spikes
Biological systematics
An area of biology that studies biological diversity and the evolutionary relationships of organisms
Genetics
An area of biology that studies how genetic material changes over time
Ecology
An area of biology that studies how organisms have evolved to fill their roles within an ecosystem
Why is it challenging to choose influenza strains to include in vaccines?
Because the virus can evolve quickly, and may have changed before flu season
Muscular: Cytokine Action
Breakdown of the muscle fibers and accumulation of fluid
Common symptoms associated with the influenza virus
One of the first symptoms of an influenza virus infecting the respiratory system is an accumulation of fluid in the lungs. As the epithelial cells lose their function, they undergo apoptosis, which in turn causes inflammation of the tissue. The inflamed tissue activates the immune system. All other flu symptoms are not the direct result of the influenza virus. The symptoms start after the release of chemical signals from the immune system's white blood cells, called cytokines, which alarm the organ systems of the body that a pathogen is present. Several effects on the body system due to the release of chemical signals from the immune system are a loss of appetite, joint and muscle aches, headache, fever, and chills.
Evolution is described as the change in heritable traits of a(n) __________ over a period of time.
Population
Nervous: Cytokine Action
Presence of cytokines tells the hypothalamus in the brain to increase the body temperature
Erasmus Darwin
Proposed that evidence from animal development and animal breeding shows that species may evolve over time
Charles Lyell
Proposed that the Earth's surface is dynamic and constantly changing
Georges Cuvier
Proposed the idea of catastrophism; he believed that all species were created at the same time, yet catastrophic events have caused some species to go extinct and studied the fossil record and noticed that fossils showed a succession of different forms of life over time
Jean-Baptiste Lamarck
Proposed the idea referred to as inheritance of acquired characteristics
Digestive: Cytokine Action
Reduces actions of appetite centers in the brain
Fitness
Reproductive success among individuals with favorable traits, which they pass on to the next generation
Common symptoms associated with the influenza virus
Sore Throat Congestion, body aches, fever, etc
Which characteristic of proteins allows influenza to specifically target its host cells?
Specific, complex, three-dimensional shape
History of Spanish flu
Influenza virus has continued to be a significant threat to global public health because it is highly infectious and can evolve very rapidly. Each year, 3 to 5 million people are infected with influenza worldwide, resulting in an average of 500,000 deaths. However, when a new variant of the virus evolves, the consequence can be far worse. In 1918, a variant of the H1N1 influenza virus, the Spanish flu, caused a pandemic and infected over 500 million people across the globe. The Spanish flu was the result of antigenic shift when two different influenza viruses infect the same host and a new form of the virus was manufactured. Because the change in the virus was so rapid, the immune system of humans was unable to respond to the virus. The death toll was estimated between 30 to 50 million people but could have been higher, since the exact numbers are impossible to know due to the lack of medical records.
Which contains more genes? Living things or viruses?
Living Things
Cytokines released in the immune response
Loss of appetite
When comparing species, some traits are more common in who than what?
More commonly in closely related species than distantly related ones
Increased blood flow and collection of immune cells in the respiratory tissues causing what flu symptom?
Mucus production
describe how the process of natural selection leads to evolution
Mutations in a gene can produce a new or altered allele that may encode for a unique trait. The new trait could be advantageous or disadvantageous to members within a population but is only able to persist if the new allele is heritable . b. The differences between heritable traits of organisms of a population, also known as genetic variation , is the primary force driving the mechanism of natural selection . c. Natural selection leads to an evolutionary change due to differential survival and reproduction rates of individuals, because of differences in traits. d. When some individuals with certain traits in a population have a higher survival and reproductive rate than others, they pass on these better adapted genetic features to their offspring. e. The change in the heritable traits of a population continues because natural selection increases the frequency of the advantageous trait in the population and decreases the frequency of detrimental traits. f. Over many generations, natural selection leads to evolution , an explanation for the process of how organisms change over time.
describe the path of influenza through the body
The influenza virus enters the human body through the mouth or nose. 1 The influenza virus travels down the pharynx into the trachea and lungs. 2 The H spikes of the influenza virus identify the target cells of the respiratory system by detecting the presence of specific glycoproteins. 3 The N spikes of the influenza virus break down the membrane of the host cell, and the virus enters the host cell. 4 The replication of the influenza virus occurs immediately and within just a few hours disrupts the function of the lungs. 5 Inflammation in the lungs in turn activates the immune system, which sends a host of cells to the respiratory system. 6 Various flu symptoms such as congestion, cough, body aches, and chills are due to the body's response to the activation of the immune system.
Which viral life cycle includes integration of genetic information with the host cell DNA and a latent period?
The lysogenic cycle
Embryonic evidence
focuses on embryo comparisons because some features may be present in the embryo that are not apparent in the adult form.
The genetic material ________ a history of the organism's evolutionary past
is
the fossil record
is a line of evidence that provides information on transitional species.
anatomical evidence
is the comparison of physical structures between species.
The closer two organisms are related, the more time for what?
less time there is for mutations to change their genetic info for a trait
There are two basic methods by which the influenza virus changes its genetic information
mutations or reassortment
In support of the idea that species change over time, Darwin proposed a four step process called
natural selection
Antigenic drift
occurs when a mutation causes a change in the H and N spikes on the influenza virus.
When fossils are arranged and compared according to their age, from _______, successive evolutionary change becomes apparent.
oldest to youngest
The genes of a virus contain
the instructions needed to manufacture its protein capsid and surface spikes (if it has spikes).
Natural Selection favors what?
variation, which increases the ability of the individual to reproduce and pass the trait on to the next generation, and acts against detrimental traits
The target cells of influenza virus, which are epithelial cells in the respiratory system, are identified by the virus because
viral capsid proteins (spikes) identify specific glycoproteins embedded in the host cell membrane.
Populations Become Adapted to Their Environment
-Natural selection increases the frequency of the advantageous trait in the population and decreases the frequency of detrimental traits
Production of flu vaccines
-People with egg allergies should pay attention to how the flu vaccine is made, since some flu shots may contain remnants of eggs due to the egg-based technology used to make the flu vaccine. -Vaccines contain either inactivated or weakened viruses. -Vaccines include additives to preserve the vaccine's contents before use.
Individuals Struggle to Exist
-Population produces more offspring than can survive -Competition exists among individuals for available resources
Charles Darwin
-South America and the Galapagos Islands -Biogeography; similar but distinct species are found on near by, similar islands -Extinct animals resemble living animals of the same region -Observations provided him with his ideas on how natural selection drives evolutionary change
Alfred Russel Wallace
-South Pacific Islands -Biogeography; similar but distinct species are found on nearby, similar islands -Observations led him to propose the concept of speciation
Which process by which the influenza virus evolves?
A mutation that changes the viral spike is introduced into the genetic material
Describe the structural components of a virus.
A virus is a type of intracellular parasite that finds a host cell and hijacks its metabolic machinery so that cell may produce more copies of the virus. Varying considerably in shape and the different types of cell they infect, all viruses have two components. Component 1, the genetic material, contains a relatively small number of genes. Component 2, the capsid, is a protein coat that surrounds the genetic material. Some viruses may also possess an envelope that surrounds the capsid. The structure is actually a remnant of the host cell and not made by the virus.
Direct effects of influenza virus on body systems
-Apoptosis of epithelial cells lining the respiratory system -Accumulation of fluid in the lungs due to the disruption of respiratory cells function -Activation of the immune system due to inflammation in the lungs
Disruptive Selection
-Changes in the environment cause the average variant to be detrimental -The population distribution will favor the variants at the ends of the distribution, splitting the distribution into two peaks.
Directional Selection
-Changes in the environment direct natural selection to favor the variation at one end of the distribution -The population distribution of the trait shifts toward the extreme
The genes of a living thing
-Contain the information needed to produce all of the proteins for cellular metabolism -contain info needed to produc e RNA
Trivalent Vaccine
-Contains different strains of the three viruses -Contains two A viruses -Contains one B virus -Virus particles are inactivated and not capable of reproducing
Nasal Spray
-Contains weakened versions of influenza -May produce flu-like symptoms
By recognizing the mechanisms through which organisms change over time, or evolve, we gain insight into which of the following?
-How to design better medications such as antiviral agents and vaccines -Resistance to insecticides and antibiotics -How the organization of life on our planet reflects evolutionary history
characteristics that explain the process of natural selection
-In a population, individuals vary in their heritable traits. -In a population, individuals struggle to exist. -In a population, individuals differ in their fitness. -Over multiple generations, populations become adapted to their environment.
Individuals Differ in Their Fitness
-Individuals with favorable traits will survive at a greater rate than those without them
Timing and choosing influenza strains for a vaccine
-The influenza vaccine is designed to protect humans against three or four influenza viruses that are most likely to spread and cause a pandemic during the flu season. -Flu vaccines take up to six months to prepare and are synthesized based on surveillance information sent to the five influenza centers across the world.
Chicken Egg-based Method
-The most common way in which flu vaccines are made -Requires the longest development time to create a flu vaccine -Candidate viruses are grown in fertilized chicken eggs, extracted, killed, and remaining virus particles are used to produce vaccines
Antigenic Shift only
-The reassembly of viral genomes derives from various strains -Greater consequences for humans -Major changes to the genetic makeup of influenza strains -After the flu mutates, the immune system recognizes as a new virus
necessary for evolution to occur
-Variation for a particular trait exists within a population. -A particular trait must be able to be passed on to the next.
components of a flu vaccine
-Weakened viruses or inactive viral particles -Three to four strains of the influenza virus -Additives, including antibiotics, stabilizers, and remnant egg proteins
The genes of the viral genome
-contain the instructions needed to produce a protein capsid -in some cases, contain information to produce surface glycoproteins
Characteristic of DNA
-the only genetic material found in known living things -nitrogen bases are A,T,G,C -double stranded
steps in producing vaccines with fertilized eggs, beginning with the first step at the top
1. Inject virus into fertilized chicken eggs 2. Eggs incubate while virus replicates 3. Extract liquid portion of eggs 4. Inactivate (kill) viruses 5. Isolate and purify viruses
Proteins produced by the flu virus that disrupt the normal function of epithelial cells causing what flu symptom?
Congestion/trouble breathing from fluid accumulation in the lungs
Mutations are _______occuring in the genetic material
Constantly
describe how both fossils and living organisms provide record of evolutionary change
Darwin described the process of evolution as descent with modification, a progression in which species change and eventually give rise to new species over time. All living things, therefore, can trace their descent to an ancient common ancestor. Evidence of long-term evolutionary change starts with the fossil record, which provides evidence for the past existence of species that are now extinct. Although it is not a complete record of evolutionary history, it not only provides evidence of what organisms were like but also gives an indication of how they evolved over time. Anatomical features shared between organisms, whether visible as an adult or only visible during embryonic development, can indicate a trait has been inherited from a common ancestor, and the organisms have shared evolutionary ancestry. If two or more species share a unique physical feature, such as a similar forelimb structure, they may have inherited this feature from a common ancestor. Physical features shared due to evolutionary history are said to be homologous.
explanation of the relationship between biology and evolution
Evolution is the unifying theme of biology. This process helps to explain nearly every aspect of the biological sciences.
describe the scientific evidence that evolution does occur
From the perspective of a biologist, evolution is one of the unifying theories, or a widely accepted explanation for how the natural world works. Evolution is supported by experimental evidence from all branches of biology, and scientists continue to test, evaluate, and refine their understanding of how evolution impacts life. Below are the different lines of evidence. Line of evidence 1, anatomical evidence, is the comparison of physical structures between species. Line of evidence 2, genetic material, is the comparison of genetic and biochemical similarities to indicate evolutionary relationships. Line of evidence 3, the fossil record, is a line of evidence that provides information on transitional species. Line of evidence 4, embryonic evidence, focuses on embryo comparisons because some features may be present in the embryo that are not apparent in the adult form. The accumulation of evidence supports that species change over time and that this change is the result of evolution by natural selection.
Structural components of a virus
Genetic Material and Protein Capsid
characteristics of all viruses
Genetic material and protein capsid
Body System: Nervous symptoms
Headache and fever
Describe the genetic material of viruses and living things
The set of instructions or genetic material used by living organisms is DNA. The sequence of nucleotides that holds a message inside DNA, known as genes, is decoded by the cell to make RNA and proteins; molecules that are needed for all cells to perform their cellular functions. In viruses, the genetic material may be either DNA or RNA. With only a few genes, the genetic material of a virus contains the instructions needed to manufacture the proteins that compose the capsid surrounding the virus and the proteins used to identify the type of host cell for the virus.
How does the influenza A virus target a host cell?
The virus has H spikes that are specific to receptors on the surface of the host cell.
Which of these is a description of how the flu affects the body systems?
The virus releases proteins that disrupt respiratory epithelial cells and the immune system releases cytokines in response to the virus that cause multiple symptoms in the respiratory and other body systems.
What role do H spikes play in influenza A infections?
They identify a specific glycoprotein embedded in the membrane of a host cell.
explains one of the processes by which the influenza virus evolves?
Two different forms of the same virus infect the same host cell and a new virus is created with parts of each form.
Naming influenza
Type of spikes found on the surface of the virus Type of influenza Location of isolation Strain number Year of isolation
difference between the lytic and lysogenic cycle
Upon inserting its genetic material into the target cell, the virus can proceed into one of two cycles of viral reproduction. In the lytic cycle, the virus immediately begins to use the resources of the host cell and most likely results in the destruction of the host cell. There are five stages to the lytic cycle. Stage 1, attachment, is when the structure of the proteins in the capsid allows it to recognize and target specific cells for infection. In step 2, penetration, the genetic material of the virus enters the host cell either by direct means or by endocytosis. In step 3, biosynthesis, the virus hijacks the host cell's machinery to manufacture new capsid proteins. Step 4, maturation, is the assemblage of new viruses, and Step 5 involves the release of the new viruses. In the lysogenic cycle, the viral DNA integrates into the host cell genome after penetration. Remaining inactive or latent, viral reproduction is delayed until some environmental factor signals the virus to reenter the lytic cycle.
Which of these best explains how influenza vaccines are produced?
Viral strains are selected well ahead of flu season based on their threat and our ability to make a vaccine against them. Vaccines are then produced using one of three common methods. This process can take up to six months.
Describe how viruses reproduce
Viruses are typically a piece of genetic material encased in a protein capsule. They are only capable of reproducing once inside a living host cell.
best general explanation of how viruses reproduce?
Viruses use one of two life cycles, both of which take over a host cell's resources, in order to copy themselves.
