409 Quiz 4

Bacteria sex and reproduction

1. These taxa separate sex and reproduction 2. Genetic exchange occurs among taxa that are much more distant from one another than eukaryotic recombination 3. Gene flow is unidirectional and involves a small amount of the genome a. Gene flow may trigger divergence in bacterial pops while the opposite is true in eukaryotes

Limitation to RNA world

Catalytic RNAs have not been found to replicate themselves

Morphological is arbitrary

Microbes dont have many feautures

Antigenic drift in influenza

Minor antigenic changes in HA and NA Allow the virus to elude some host immunity

morphospecies concept

The definition of a species is a population or group of populations that have measurably different anatomical features from other groups.

Allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

coincidental hypothesis

Virulence is not the target of selection itself but an accidental by product

chromosomal inversion

When part of the chromosome becomes oriented in the reverse of its usual direction

Antagonistic pleiotropy

a. Emergence of a mutant that leads to new use of a new resource

Early life

a. No complex metabolism b. Anaerobic because of a lack of oxygen in atmosphere

Dispersal

a. People moving away from original pop

Secondary contact and its outcomes

a. Species that Diverged in allopathy and come into contact with one another b. Possible outcomes - Select against hybrids - Selection favors hybrids in novel habitat - Selection favors hybrids in transitional habitats

vector bourne

asymetric

Virulence

harm caused to host

RNA world hypothesis

hypothesis that RNA served as the genetic information of early life Cech and Altman

A good species concpet

i. Be mechanistic ii. Be testable iii. Accurately reflect evolutionary history

antigenic sites

specific parts of a foreign protein that the immune system recognizes and remembers

Vicariance

the physical splitting of a habitat

assortative mating

the type of mating that occurs when an organism selects a mating partner that resembles itself

Integrons

this non-mobile genetic element is unique because it carries genes in circular units called gene cassettes which are freely transmissible between these elements

Speciation steps

variation, isolation, selection

Modes of transmission

Vector borne, sexual contact, air-bourne, waterbourne

Holy grail of RNA world

1. Gaining the ability to self-replicate a molecule or collection of molecules can be the transition to "life" 2. Researchers are trying to recreate such an RNA

Compartmentalization

1. How do you get a membrane without something hereditary? Miller's experiment - wrong kind of lipid bilayers formed

phylogenetic species concept

A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

Morphological uses

Asexual and Sexual Extant and extinct

shortsighted evolution hypothesis

Because pathogens reproduce within hosts, traits that increase their short-term fitness may actually be detrimental High virulence could cause immediate fitness but it may spell low long-term fitness if the pathogen is too virulent to be passed on

Ribozymes

Genotype and enzyme in one step

Oparin issues

How did proteins and nucleic acids arive Chirality Activation is hard to explain without a membrane Protein and nucleic acid instability in water

Fitness hybrids < Parents

Hybrid zone is narrow and short lived

Fitness hybrids = parents

Hybrid zone is wide and long lived

Antibiotic mechanisms

Interference with a specific step in bacterial cell wall synthesis Inhibition of bacterial protein synthesis Interruption of bacterial nucleic acid synthesis Interference with normal bacterial metabolism

Biological issues

Not useful for extinct or asexual organisms

Hemagglutinin

One of the enzymes found on the surface of the Influenza virus. It is responsible for binding the virus to the cell that is being infected.

Oparin and Haldane

Oparin and Haldane were two scientists who proposed in the 1920s that the primitive atmosphere contained the following gases: methane, ammonia, hydrogen, and water. They believed that these gases collided, producing chemical reactions that eventually led to organic molecules.

biological species concept

Species is a group of populations whose members have the potential to produce fertile offspring.

Phylogenetic uses

Useful for micro and macro organisms Distinguish cryptic species Problem is it increases the number of species there are

divergence mechanisms

i. Genetic Drift - Neutral evolution especially in new, small pops could cause rapid divergence ii. Natural Selection - Selection for habitat or resource use is expected to differ after isolation leading to divergence i. Sexual Selection - Changes in mate-choice promote divergence because they directly affect gene flow

the case for RNA as an early life form

i. Most conserved and universal component of information transfer. Ribosomes are built on an RNA frame and use RNA adaptors to function ii. RNA on ribosome carries out catalytic function iii. Basic units of energy are ribonucleosides - ATP and GTP

LUCA

i. No one single common ancestor but their was a community of organisms exchanging genes until a Darwinian threshold was reached

Resistance cost

less growth

antigenic shift

major change in influenza virus antigen due to gene reassortment

Instability

may be explained by clay-catalyst

trade-off hypothesis

natural selection should favor pathogens that strike an optimal balance between the costs and benefits of harming the host.

Symmetric speciation

occurs when two subpopulations become reproductively isolated within the same geographic area