Evolution, Viruses, and Prokaryotes Flashcards
Prion
Misfolded protein which causes a chain reaction leading to more misfolding. Examples: Mad cow, Kuru, Creutzfeldt-Jakob, Chronic Wasting Disease, Scrapie, Feline Spongiform Encephalopathy, Zoo animal encephalopathy, etc
Nucleoid
Complex of RNA, DNA and proteins in prokaryotes that forms a structure visible under light microscope
Virulent Virus
Virus capable of causing disease
Virus in lytic cycle

viral envelope
A membrane that encloses the capsids of some viruses. Normally includes specialized proteins that attach to host-cell surfaces.
Enveloped viruses form envelopes from the host cell which protect against detection by the immune system.
Host cell may not die from lysis, but will die from degrading cellular membrane
Kingdoms in Eukarya
Protista, Fungi, Animalae, Plantae
Phylogeny refers to
evolutionary relationships that are based on shared characteristics including physical traits, genetics, and behavior
Speciation
Members from a single species have evolved into different groups that can no longer produce fertile offspring
Gene pool
Total of all alleles in a population

Bacteriophage
a virus that infects and replicates within bacteria
Bacteriophage are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures.
many of the most complex capsids
Injects nuclei acids into host cell through tail
Viral enzymes digest hole in cell wall
Host cell in viral infection
Cell that is being infected
Lysogenic infection:
In a lysogenic infection, the viral DNA is incorporated into the host genome, or, if the virus is an RNA virus and it possesses the enzyme reverse transcriptase, DNA is actually reverse-transcribed from RNA and then incorporated into the host cell genome. When the host cell replicates its DNA, the viral DNA is replicated as well. A virus in a lysogenic cycle is called a temperate virus.
A host cell infected with a temperate virus may show no symptoms of infection. While the viral DNA remains incorporated in the host DNA, the virus is said to be dormant or latent, and is called a provirus (a prohage if the host cell is in a bacterium). the dormant virus may become active when the host cell is under some type of stress. ultaviolent light or carcinogens also may activate virus. When the virus becomes active, it becomes virulent.
Provirus or Prophage
Virus incorporated into host DNA
RNA-dependent RNA polymerase (RdRP)
Enzyme that can synthesize new RNA from template RNA. Makes either RNA+ from RNA- or vice versa
RNA+ encodes for proteins
RNA- complimentary strand that cannot encode for protein
Viruses preferentially carry either RNA+ or RNA-
Ontogeny recapitulates phylogeny?
Embryonic development retraces the steps of evolutionary history
Latent period with viral infection
Period from infection to lysis
Retrovirus
ssRNA virus that transcribe RNA into dsDNA by using reverse transcriptase (carried by retrovirus)
Example: HIV
Virus
Tiny infectious agents that usually lack cellular machinery to reproduce and leverage the transfer of genetic information to cells to reproduce. Not considered living. Can contain DNA or RNA
Known as viral particle or virion as mature virus outside of host
Can be thought of as a eukaryotic nucleus
Natural selection
Genes that are advantageous in environment are preferentially passed down from generation to generation
Random Mating
Organisms are equally likely to mate with each other regardless of their phenotype
Taxonomical Classification System
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Prokaryotes
single-celled organism that lacks a membrane-bound nucleus (karyon),mitochondria, or any other membrane-bound organelle.
Two domains- Archaea and Bacteria
Differential Reproduction
Animals within a species having different amount of reproduction to allow success of the organism to live on
Mutational Equilibrium
Rate of forward mutations exactly equals rate of backward mutations.
Rare in real populations.
Evolutionary time can be measured by gradual changes in the genome.
Mammals belong to class __ and Phylum ___
Mammalia, Chordata
Reasons organisms cannot produce fertile offspring
Geographic isolation, temporal isolation, genetic incompatibility

How does a viral infection happen?
- Begins when a virus adsorbs to a specific chemical receptor (usually glycoprotein) site on the host’s cell membrane .
hardy weinberg equilibrium equations
p^2+2pq+q^2=1
p+q=1
Hardy Weinberg equilibrium
- Mutational equilibrium
- Large population
- Random Mating
- Immigration or Emmigration must not change gene pool
- No selection for fittest organism
Conditions under which no evolution occurs. Idealization and not exactly possible
Polymorphism
Gene that has multiple alleles, corresponding to distinct forms of a phenotype

Archaea
Domain consisting of unicellular prokaryotes that have cell walls lacking peptidoglycan (MAIN DIFFERENCE FROM BACTERIA); corresponding to the kingdom Archaebacteria
Bacteria shapes
Cocci (spherical)
Bacilli (rod-shaped)
Spirilla (spiral-shaped)
Spirochete (spiral shaped, but longer usually than spirilla)
Filamentous (long and thin string-like)
Vibrio (Slightly bent rod)
Describe the process of viral infection
Virus attaches to cell receptor, and either gets endocytosed/exocytosed by cell or injects it’s genetic material through cel membrane/wall
Viral DNA then translocates to the nucleus, to hijack cellular machinery for DNA replication and transcription
Persistent versus Latent Viral Infection
Latent viruses have alternating periods of replication and asymptomaticness. Herpes B is persistent, herpes simplex is latent
No selection for fittest organism
No members of population exploit environment more efficiently than others
Genetic Drift
random change in allele and genotype frequencies as a result of a sampling error
- the chances of a genetic drift increases with decrease in population size
- small population size and genetic drift are associated with bottleneck effect
– the result of unselective elimination of most members of a population
- many alleles can be lost by the random loss of individuals from the populations (when the population recovers, genetic variability is reduced)
Lack of immigration and emmigration
New alleles not introduced and old alleles not eliminated due to movement of individuals in population
Allele
An allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific
Three domains of life
1) Bacteria (prokaryotic)
2) Archaea (prokaryotic)
3) Eucarya (eukaryotic)
CARL WOESE (1928-) classified them
Viruses do not fall under any of these classifications because they are not prokaryotic or eukaryotic
Viroid
naked circular, highly complementary, single stranded RNA that is infectious with NO PROTEIN COAT. Does not encode genes (USES plants RNA-dependent RNA polymerase to replicate
Phylogeny
- The study of how living and extinct species are related
- the study of evolutionary history of different groups of organisms
Lytic infection
Virus commandeers host cell’s synthetic machinery to replicate viral
Proteins
RNA -> Proteins
Cell may lyse with viruses or viruses may be released one at a time
Specialization
Organism tailors to specific niche in environment through behavior or resources, usually refers to subset of species rather than whole species
Nonenvelopes Viruses
Viruses not surrounded by cell membranes.
Typically cause cells to lyse in the lytic stage
Parasitic relationships
Relationships which only benefit one organism
Pathogenic bacteria are parasitic
Species
All organisms that can reproduce fertile offspring with one another
Types of genetic material viruses can hold
Single stranded DNA (ssDNA): Translocates to nucleus and DNA polymerase replicates complimentary strand
Double stranded RNA (dsRNA): Strands separate to form RNA- and RNA+
Genetic Material in Prokaryotes
Typically a single circular double-stranded molecule of DNA.
Molecule is twisted into supercoils
Archaea- have histones
Bacteria- have proteins distinct from histones
Constituents of a Virus
Capsid- protein coat
Genetic material- DNA or RNA
No organelles or nuclei
Usually an envelope- lipid rich
Non random mating
Any mating system in which males are not randomly assigned to females.
-females choose out of visual appeal or those who live nearby, etc.
Symbiotic relationships
Relationship beneficial to two organisms
E.g., bacteria in intestinal tract help humans digest food efficiently and benefit by receiving nutrients
Adaptation
Genetic or behavioral changes that are advantageous in given environment
How can we measure success of gene?
Percent increase in representation in gene pool of next generation
Bacteriophage
A virus that infects bacteria
Injects nuclei acids into host cell through tail
Viral enzymes digest hole in cell wall
Causes of speciation
Polymorphisms make speciation possible. Inbreeding (mating of relatives) increases num of homozygous individuals in population and w/ geographic separation can cause speciation. Random events can cause a bottleneck. Specialization and adaptation
