Bio 1108 Unit 1 PPT Study Guide
Microevolution uses
population genetics to study of the change in: -Allele frequencies -Genotype frequencies -Phenotype frequencies
Muller's Ratchet
process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner
Antigens
are molecules capable of stimulating an immune response.
fast-lived species
are more likely to transmit zoonotic pathogens.
Antibodies
(immunoglobins) are Y-shaped proteins produced by B cells of the immune system in response to exposure to antigens.
Salk's vaccine
- first effective vaccine against polio - is an inactivated polio vaccine (IPV) (Formalin inactivated)
mRNA vaccine
-Faster because mRNA molecules are easier to produce -Components are injected into the arm and serve as instructions for the body to make microbial protein
Traditional Vaccine
-Microbial protein or inactive microbe -Slower and more difficult to produce the right type of protein -Components are made in a lab and injected into the arm to stimulate immune response
Characteristics of agrarian societies that favor zoonosis
-Sharing a home environment with livestock -Rural households where livestock such as chickens & pigs may live downstairs or in adjoining space
Sabin's vaccine
-live attenuated vaccine -oral vaccine
The invasion of the virus is a two-step process:
1)Attach to the ACE2 receptor. 2)Fuse to the cell membrane via TMPRSS2
Genotype frequencies stay the same if five conditions are met.
1. Large population size (therefore no genetic drift) 2. No gene flow among populations (i.e. no emigration or immigration). So no animals moving or for plants, no seeds or pollen moving. 3. No mutations (i.e. no new alleles added to gene pool) 4. Completely random mating among all individuals within a population 5. No natural selection (i.e. all traits contribute equally to survival)
Why is the size of the human population a problem?
1.Interconnectivity of our species across the planet 2.With increasing growth of our species, there has been a steady decrease in: §Habitat §Biodiversity 3.Greater opportunities for mutation & evolution of new variants
Viruses
20-400 nm Between living and non-living Virus does not respond to antibiotics.
The genome of Covid codes for how many structural proteins
4
Mutation
A change in a gene or chromosome.
genetic drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.
R0
A number that represents how quickly a contagious disease is spreading.
Naïve population
A population that has never been exposed to a specific antigen & therefore has no immunologic memory of the pathogen nor has there been selection for individuals who have an innate ability to resist infection by that pathogen.
Which pandemic has killed the most people?
A.Bubonic Plague.
Zoonosis
An infectious disease that is transmissible from animals to humans.
Imprinting
Any kind of phase-sensitive learning that is rapid and apparently independent of the consequences of behavior.
Where did SARS-Cov-2 come from?
Bat-> mammal Bat-> human transmission •Wet seafood/exotic animal market
Where did SARS-CoV-2 come from?
Bats, Pangolins, all animals can carry the virus.
Human Immunodeficiency Virus (HIV)
Belongs to retrovirus family * 2 identical RNA strands encode 15 proteins • Integrates into the patient's genomeDoes not contain "proof-reading" enzymes
H1N1
Easily spread, rarely fatal
Influenza strains are designated by the letters "H" and "N" (e.g. H1N3) What do these letters stand for?
Hemagglutinin and Neuraminidase.
Which of the following is NOT an explanation to account for the rapid increase in the number of strains of SAR-CoV-2?
Humans interacting with wild bats.
MERS-CoV
Middle East Respiratory Syndrome Coronavirus
antigenic drift
Minor change in influenza virus antigens due to gene mutation
There was also recombination between pangolin & bat coronoviruses that gave rise to
SARS-CoV-2.
SARS-COV
Severe acute respiratory syndrome coronavirus
Bacteria
Size 1000+ nm Living/Non-Living Living organisms Treatment Antibiotics
Why would allele & genotype frequencies change over time?
The action of one or more Evolutionary Factors
spillover event
Viruses can occasionally, but quite rarely, move from one population to another
Founder effects
Where a small number of colonists leave the source population & start a new small population.
Genetic bottlenecks
Where the population size has been greatly reduced by something, such as disease, but then later grows larger again.
Second strand of nucleic acid
Without this there is no matching strand to compare against and correct any errors (mutations) that might arise.
Why do bird flu and other forms of the influenza virus have a high rate of mutation?
due to the fact that they are typically passaged between humans, fowl, and pigs.
A completely naive population
a pathogen will propagate through susceptible hosts in an unchecked manner following effective exposure of susceptible hosts to infected individuals. However, if a fraction of the population has immunity to that same pathogen, the likelihood of an effective contact between infected and susceptible hosts is reduced, since many hosts are immune and, therefore, cannot transmit the pathogen."
SARS-CoV-2 is NOT
a retrovirus
By binding to the spike protein of the virus...
antibodies can physically block the attachment of the virus to receptors of the target cell.
biodiversity loss
appears to increase the risk of human exposure to both new & established zoonotic pathogens.
Zoonoses
are diseases transmitted from living animals to humans.
Viral genomes
are small and can be easily sequenced.
Viruses
are the simplest of biological entities. They consist of little more than genetic material (RNA or DNA) contained within a proteinaceous structure (capsid), surrounded by a membrane (envelope) that typically has embedded proteins. They have no metabolism of their own.
If the spike protein can be blocked from binding to the ACE2 receptor then...
attachment and invasion, of the virus can be prevented and the infection stopped.
Biodiversity
benefits human health by reducing transmission of some pathogens that have already established themselves in human populations.
Leishmaniasis
can be both spread between humans (Anthroponotic) or spread between humans & other species (Zoonotic).
Small changes in the amino acid composition of the HA protein determine its
characterization
SARS-CoV-2 may be a what (resulting from recombination of the bat & pangolin coronaviruses) AND is a close relative of two other bat strains?
chimera virus
Viruses are more likely to infect different species of animals that are
closely related
Mink & cats
could have served as the intermediary, as both species carry COVID-19.
Why is it important that different pathogens have different R0 values?
developing public health strategies such as patient quarantines, facemask use, social distancing and vaccination rates.
Microevolution
examines evolution within species.
Eukaryotes and prokaryotes have evolved progressively better methods of...
gene proofreading,
Most of the technology in developing an mRNA vaccine focused on how to deliver the genes (Plasmid DNA) needed to express, translate and export the viral protein (antigen) from a host cell and delivering the instructions for the viral antigen (mRNA). All that was needed was the
gene sequence for the antigen (SARS-CoV-2 spike protein).
The essential ingredient for evolutionary change to occur is
genetic variation.
In what scenario can a virus be driven to extinction?
if there is a collapse threshold U and population size exceeds that threshold.
When biodiversity is reduced, the species most likely to disappear are large-bodied species with slower life histories, while smaller-bodied species with fast life histories tend to
increase in abundance.
Genital HPV
infection is a sexually transmitted disease (STD) that is caused by human papillomavirus (HPV).
Indirect transmission
involves transmission of the pathogen by way of a vector.
Direct transmission
involves transmission of the pathogen through physical or close contact (e.g. contaminated surfaces/air) between individuals.
The human immunodeficiency virus (HIV)
is a type of retrovirus and is the causative agent of acquired immunodeficiency syndrome (AIDS).
Evolution
is defined as a change in the genetic composition of a population over successive generations.
Population genetics
is how we study microevolution.
Hemagglutinin
is needed to enable the virus to attach to the membrane of the target host cell.
Neuraminidase
is required to release that attachment and allow the virus to go free and spread.
Reverse transcription
is the enzyme-mediated synthesis of a DNA molecule from an RNA template.
If a virus cannot attach to a cell...
it cannot invade a cell and the infection is stopped
In less-disturbed areas, however, these zoonotic reservoir hosts are
less abundant & nonreservoir animals predominate.
antigenic shift
major change in influenza virus antigen due to gene reassortment
The enzyme reverse transcriptase
makes a DNA copy of the viral RNA genome.
non-random mating
mating between individuals of the same phenotype or by those who live nearby
Human Papillomavirus (HPV) is also a type of retrovirus
meaning that it can permanently insert its genes into the DNA of the host cell. Once a person is infected with HPV they can never be completely 'cured' of the virus.
Neutral
molecular markers are used to study population genetics.
gene flow
movement of alleles from one population to another
Glycoproteins
on the surface of the envelope serve to identify and bind to receptor sites on the host's membrane.
In the mid-1990's the U.S. and many other countries switched from a whole cell pertussis vaccine (DTwP) to
one based on component proteins (acellular) or DTaP.
Once incorporated into the genome ERVs tend to stay put. Thus as they are inherited from our ancestors and accumulate over long periods of time the sequences of ERVs and their position within the genome means that ERVs are an excellent type of data for use in
phylogenetic analyses
The infection is transmitted from the
reservoir population
Antibodies against the hemagglutinin
should prevent the virus from binding to host cells and therefore prevent the infection from becoming established.
Large populations are much more resistant to chance fluctuations in gene frequency than are
smaller populations.
These frequencies are measured in one or more populations within a
species
These animals often proliferate in human-dominated landscapes, increasing the likelihood of
spillover.
A second enzyme
splices (integrates) the viral genome into the host cell genome.
H5N1
spreads slowly, often fatal
The Hardy-Weinberg principle
states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences.
Some taxa are much more likely to be zoonotic hosts than others
taxa
Genes on the viral genome
then code for new viral particles.
Selection (biology)
variation in fitness; heritable. Causes non-random changes in allele frequencies and tends to reduce variation.
Because the weakened, but live, polio virus can replicate in the host and can revert back into what type of form it is essential that every member of a community be vaccinated at the same time to avoid an outbreak within the community.
virulent form
§Neutral genetic markers are non-coding regions in the genomes of:
§Nucleus §Mitochondrion §Chloroplast
§When the planetary population of humans was lower...
§When a novel pathogen or disease arises in one population of an organism, the pathogen does not necessarily transmit to every other population in the species. §Often the pathogen will run its course in one or a few populations and then die out.
Anthroponoses
§are diseases transmitted between humans.
Strict sense genetic drift
§occurs in small populations which remain small for considerable lengths of time (i.e., generation after generation population size remains small). Populations ultimately become fixed for one allele or another.
Regions of 2 genes may have resulted from HGT & recombination between 2
§pangolin coronaviruses.
Novel Coronavirus (SARS-Cov2)
• Belongs to coronavirus family * 1 RNA strand encodes 4 proteins • Does not integrate into the patient's genome * Contains "proof-reading" enzymes
Flu (A + B)
• Belongs to influenza virus family 8 RNA strands encode between 8-11 proteins based on reading frame Does not integrate into the patient's Genone * Does not contain "proof-reading*enzymes
Factors influencing the frequency & pattern of zoonotic diseases in a community
•Extent of animal-human contacts •Socioeconomic conditions •Cultural influences (bushmeat, traditional medicine, religious practices) •Climate & environmental disasters •Human & animal movements •Animal management - intensive farming, waste disposal, wet markets