Viruses and Prokaryotes

What are viruses?

obligate intracellular parasites

What does it mean that viruses are obligate intracellular parasites?

they reproduce usings the host “equipment”

What are bacteriophages?

Viruses that infect bacteria

How do bacteriophages reproduce?

through the lytic cycle or through the lysogenic cycle

What happens in the lytic cycle?

Phage nucleic acid takes over the host cell, host transcription is stopped, host DNA digested, viral genome copied, capsid produced, infected cell produces viruses

what is produced in the lytic cycle?

infected bacterium lyses

What is an example that uses the lytic cycle?

the common cold and flu viruses

What happens in the lysogenic cycle?

Phage DNA (prophage) inserted into host chromosome, Prophage replicates with host, Prophage expressed as proteins in host, bacteria produces what the virus wants (toxins), no lysis

What is an example that uses the lysogenic cycle?

Scarlet fever, diphtheria, botulism

Without what would the lysogenic cycle be not so harmful?

without prophage genes

What are examples of bacteria defenses?

Restriction nucleases and natural selection

How are restriction nucleases a defense for bacteria?

eliminate DNA or RNA virus

How is natural selection a defense for bacteria?

receptors are no longer recognized by phage

How do prokaryotes reproduce?

through binary fission

What is binary fission?

a type of cell division where the chromosome replicates and the two daughter chromosomes actively move apart

How do prokaryotes have genetic diversity?

through rapid reproduction, mutation, and genetic recombination

What does it mean that prokaryotes have rapid reproduction?

they can divide every 1 - 3 hours meaning they have a short generation time, leading to rapid evolution

What does it mean that prokaryotes have genetic diversity through mutation?

their mutation rates are low which is compensated by rapid evolution

How do prokaryotes have genetic diversity through genetic recombination?

they have additional genetic material from other individuals through transformation, transduction, and conjugation

What is transformation?

changes in genotype and phenotype due to acquisition of external DNA from a dead bacterium

What is transduction?

movement of genes caused by viruses (bacteriophages)

What is conjugation?

transfer of genetic material between bacterial cells

What are Chemoheterotrophic prokaryotes?

function as decomposers, breaking down corpses, dead vegetation, and waste products

What functions as decomposers, breaking down corpses, dead vegetation, and waste products?

Chemoheterotrophic prokaryotes

What are Nitrogen-fixing prokaryotes?

add usable nitrogen to the enviroment

What add usable nitrogen to the enviroment?

nitrogen-fixing prokaryotes

What is symbiosis?

two species living in close contact

What is mutualism?

where both organisms benefit from the interaction

What is commensalism?

where one organism benefits and the other is unaffected

What is parasitism?

where one organism (the parasite) benefits and the other (the host) is harmed

What is biological evoltuion?

change overtime in the genetic makeup of a population of organisms, meaning changes in the frequencies of alleles overtime

What are the 3 main types in which natural selection can be presented?

Directional, disruptive, and stabilizing

What is directional selection?

favors one extreme of a trait, causing the population to shift in that direction

What is disruptive selection?

favors both extremes of a trait, while individuals with an average trait are at a disadvantage

What is stabilizing selection?

favors the average trait, while extremes are selected against