Viruses & Prokaryotes

Question 1

Individual viral particle.

Answer 1

Viron

Question 2

3 hypotheses of virus evolution:

Answer 2

Regressive Hypothesis
Progressive Hypothesis
Virus-First Hypothesis

Question 3

Virus Evolution.
De-evolution Hypothesis
States that viruses were once free-living cells or intracellular parasites that decreased in complexity and eventually lost the ability to reproduce on their own.

Answer 3

Regressive Hypothesis

Question 4

Virus Evolution.
Escapist Hypothesis
States that viruses arose simply from RNA or DNA, or from self-replicating mobile genetic material (like transports), that acquired the ability to leave their native host cell for another.

Answer 4

Progressive Hypothesis

Question 5

Virus Evolution.
Suggest that viruses existed as the first self-replicating entities, predating cells.

Answer 5

Virus-First Hypothesis

Question 6

The genome of single-stranded RNA (ssRNA) viruses can act not only to store genetic information but also as the mRNA used for protein translation.

Answer 6

Positive Sense —> (+)ssRNA

Question 7

Have a genetic sequence complementary to their mRNA.

Answer 7

Negative Sense —> (-)ssRNA

Question 8

4 types of viral capsids:

Answer 8

Helical Capsids
Icosahedral Capsids
Enveloped Viruses
Complex Viruses

Question 9

Viral Capsid
Shaped like long cylinders.

Answer 9

Helical Capsids

Question 10

Viral Capsid
Look like multifaceted 3D spheres but are formed from 20 equilateral triangles.

Answer 10

Icosahedral Capsids

Question 11

Can have Icosahedral or helical capsid and posses a plasma membrane that’s derived from their host surrounding their capsid.

Answer 11

Enveloped Viruses

Question 12

Can have Icosahedral or helical shapes with an outer shell wall or have the 2 shapes put together to form a head and tail.

Answer 12

Complex Viruses

Question 13

Viruses that infect bacteria.

Answer 13

Bacteriophages

Question 14

5 steps in the infection/replication cycles of a virus:

Answer 14

Attachment
Penetration
Uncoating (if necessary)
Replication
Assembly
Release

Question 15

Step 1 in the infection/replication cycle of a virus:
A capsid protein or envelope glycoprotein of a vision binds to a receptor on the membrane of the host cell.

Answer 15

Attachment

Question 16

Step 2 in the infection/replication cycle of a virus:
A virion enters the host cell through one of several methods - endocytosis, fusion, injection.

Answer 16

Penetration

Question 17

Method of Penetration
The host cell membrane engulfs the virion.

Answer 17

Endocytosis

Question 18

Method of Penetration
The viral envelope merges with the host cell membrane.

Answer 18

Fusion

Question 19

Method of Penetration
The contents of the capsid are injected into the host cell.

Answer 19

Injection

Question 20

Step in the infection/replication cycle of a virus if the viron entered the host cell:
The capsid is degraded, releasing its contents.

Answer 20

Uncoating

Question 21

Step 3 in the infection/replication cycle of a virus:
DNA viruses - typically exploit the existing machinery of a host cell to replicate DNA, transcribe mRNA, and direct protein synthesis
RNA viruses - replicate in a similar manner but their genetic code may also function as mRNA

Answer 21

Replication

Question 22

If a host cell not only allows a virus to attach, but also to use the cell to replicate, the cell is __________.

Answer 22

Permissive

Question 23

Step 4 in the infection/replication cycle of a virus:
Once replicated, involves packaging the viral genome into newly assembled capsids.

Answer 23

Assembly

Question 24

Step 5 (last step) in the infection/replication cycle of a virus:
Egress.
Newly assembled visions are released from the host cell via lysis or exocytosis.

Answer 24

Release

Question 25

Cell bursts open killing the cell by rupturing the membrane.

Answer 25

Lysis

Question 26

When budding occurs on the cell membrane allowing individual virions to exit without much damage. *Common with many viruses that affect animals.*

Answer 26

Exocytosis

Question 27

Programmed cell death.

Answer 27

Apoptosis

Question 28

A lag between when the virus infects the host and when it replicates and affects the host.

Answer 28

Latency

Question 29

2 main cycles of virus reproduction:

Answer 29

Lyric Cycle Lysogenic Cycle

Question 30

*Virus Reproduction* Viruses quickly reproduce inside the host cell until it bursts open, releasing many new viruses. -most common

Answer 30

Lytic Cycle

Question 31

*Virus Reproduction* Viral DNA becomes a part of the host’s genome and can persist for a long time before environmental triggers cause the virus to switch to the lytic cycle. -slower -only seen in viruses that infect bacteria

Answer 31

Lysogenic Cycle

Question 32

*Virus Reproduction* Follows the steps of attachment, penetration, Uncoating, replication, and assembly *BEFORE* finally ending with the production of so many virions that the host cell lyses (bursts) and releases them all.

Answer 32

Lytic Cycle

Question 33

*Virus Reproduction* Slower process through which viral DNA becomes integrated into the host genome. Only seen in bacteria and the viruses that infect them (bacteriophages). -In this cycle, DNA from the bacteriophage enters the host cells and becomes part of the host’s genome, where it can persist indefinitely.

Answer 33

Lysogenic Cycle

Question 34

Virus that infects bacteria.

Answer 34

Bacteriophage

Question 35

Replication of bacteriophages.

Answer 35

Lysogeny

Question 36

Environmental triggers eventually cause a virus to shift from the lysogenic cycle to the lytic cycles. The prophase DNA is removed from the host DNA and the virus enters the lytic cycle.

Answer 36

Induction

Question 37

Koch’s Postulates:

Answer 37

1. The microorganism can be found in high abundance in symptomatic individuals. 2. The microorganism can be isolated from a symptomatic individual and grown in a laboratory culture. 3. Inoculating a healthy individual with the cultured microorganism produces the disease. 4. The microorganism in the inoculated, diseased individual can be retrieved and identified as the same microorganism from the original diseased host.

Question 38

Disease-causing microbes (infection) transmitted from a parent to offspring.

Answer 38

Vertical Transmission

Question 39

Disease-causing microbes (infection) transmitted from one individual to another. Infection from one person to another (usually due to contact with bodily fluids).

Answer 39

Horizontal Transmission

Question 40

Symptoms develop and resolve within a relatively short period of time.

Answer 40

Acute Disease

Question 41

Symptoms last for longer periods of time or event indefinitely.

Answer 41

Chronic Disease

Question 42

When a disease occurs suddenly and in high numbers within an area.

Answer 42

Outbreak

Question 43

Ensues when a disease outbreak spreads to a greater number of people over a larger area.

Answer 43

Endemic

Question 44

Is declared if the original outbreak rapidly spreads to afflict multiple countries, continents, or the entire globe.

Answer 44

Pandemic

Question 45

Viruses that have the capacity to cause cancer.

Answer 45

Oncogenic Viruses

Question 46

Weakened viruses.

Answer 46

Attenuated Viruses

Question 47

A single viral protein.

Answer 47

Prion

Question 48

A circular strand of RNA.

Answer 48

Viroid

Question 49

Proteinaceous infectious particles that contain no genetic code. Extremely hardy and don’t break down in the intestinal tract. Irregular variant of a normal protein produced by the host. Replicate by entering a cell, binding to the normal version of the protein, and converting that protein into the infectious variant, forming a new prion. —> Go on to alter more normal proteins (so prion replication increases exponentially. -ex. *Spongiform encephalopathy* —> “mad cow disease”

Answer 49

Prions

Question 50

Small, circular ssRNA particles that aren’t housed in a capsid nor do they produce any proteins. Their sole function is to reproduce RNA sequence using the host cellular machinery

Answer 50

Viroids

Question 51

Additional layer surrounding the cell wall of bacteria that serves as camouflage from a host’s immune system and to aid in attachment to surfaces.

Answer 51

Gelatinous Capsule

Question 52

How genetic material is shared in prokaryotes:

Answer 52

Transformation Transduction Conjugation

Question 53

Fragments of DNA are taken in from the environment and incorporated into the genome.

Answer 53

Transformation

Question 54

Genetic material is transferred from one cell to another by a bacteriophage (from one bacterial cell to another).

Answer 54

Transduction

Question 55

A donor cell extends a long, hollow pious to a recipient cell, forming a conjugation bridge.

Answer 55

Conjugation

Question 56

Fragment of DNA are taken in from the environment and incorporated into the genome.

Answer 56

Transformation

Question 57

Genetic material is transferred from one cell to another by a bacteriophage.

Answer 57

Transduction

Question 58

Involves the duplication and transfer of a plasmid from a donor cell to a recipient cell via pious bridge.

Answer 58

Conjugation

Question 59

Primary mode of reproduction for prokaryotes. Results in the formation of 2 identical daughter cells. Genetic material in the nucleotide region is duplicated and separated. —> As the DNA is replicated, the cell enlarges and begins to produce material for a new cell wall, creating a septum through the equatorial region of the cell, the cell pinches inward to form 2 separate cells. DOES NOT allow for the recombination/exchange of genetic material.

Answer 59

Binary Fission

Question 60

A symbiosis in which one species benefits and the other is unharmed.

Answer 60

Commensalism

Question 61

Pathogenic prokaryotes are considered parasites. —> Harming their hosts by infecting them.

Answer 61

Parasitism

Question 62

Bacteria are used to degrade/remove pollutants from the air, water, and soil by processing materials like raw sewage, petroleum/crude oil spills, and industrial waste.

Answer 62

Bioremediation

Question 63

Thin films of bacteria that stick to surfaces.

Answer 63

Biofilms