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