Final Exam

Question 1

Bacteriophages are viruses that ____ _____

Answer 1

infect bacteria

Question 2

Viruses recognize their host through interactions between molecules on the ______ of the virus and host. Such interactions lead to viral genetic material being _____ into the host.

Answer 2

surface; injected

Question 3

Once a virus injects viral genetic material into the host, there are two pathways that can occur. What are they and explain

Answer 3

1. lytic – makes more virus (viral DNA is packaged in newly formed virions)
2. lysogenic – can be incorporated into the host genome

Question 4

Transduction is the process by which DNA is

Answer 4

transferred from one host to another by a bacterial virus

Question 5

In lytic pathway, sometimes host DNA gets packaged instead of the viral DNA, such virions are called

Answer 5

transducing particles

Question 6

The transducing particles do not contain all of the viral DNA, and cannot function as ______ ______, but they can still ______ host cells and _______ their DNA which can get ______ into the host genome or ______ the host in some manner

Answer 6

normal virions, recognize, inject, integrated, influence

Question 7

Koch’s Postulates were developed to

Answer 7

create guidelines for examining causal
relationships between microorganisms and disease

Question 8

In this lab, we will
attempt to perform Koch’s Postulates on a bacterium (_____ _______) that causes potatoes to
rot (____ ____ ____).

Answer 8

Erwinia carotovora, potato soft rot

Question 9

Koch’s postulates (4)

Answer 9

1. The organism must be found in all animals (or plants or other) suffering from the disease, but
   not in healthy animals
2. The organism must be isolated from a diseased animal (or plant or other) and grown in pure
   culture
3. The cultured organism should cause disease when introduced into a healthy animal (or plant
   or other)
4. The organism must be reisolated from the experimentally infected animal (or plant or other)

Question 10

epidemiology is

Answer 10

The branch of microbiology and public health devoted to studying the spread of
disease

Question 11

What is an epidemic

Answer 11

ituation in which an infectious disease spreads
from one individual to another until a considerable number of people are involved

Question 12

Bacteria are sometimes able to grow in an environment that could not normally
support their growth by utilizing materials excreted by ______ ______. This phenomenon is termed _____-_______ or ________

Answer 12

other organisms; cross-feeding or
syntrophism.

Question 13

Lecture 7

Answer 13

Lecture 7

Question 14

Bacteriophages do not harm ________

Answer 14

eukaryotes

Question 15

Bacteriophages are/are not enveloped?

Answer 15

are NOT

Question 16

All viruses require _____ ____ for reproduction

Answer 16

host cell

Question 17

Viruses all face the same needs for host infection: (5)

Answer 17

1. Host recognition and attachment
2. Genome entry
3. Cellular takeover/synthesis of viral components with cellular machinery
4. Assembly of virions
5. Exit and transmission

Question 18

In a viral growth curve what is the first period?

Answer 18

eclipse period

Question 19

What happens in the viral growth curve: eclipse period?

Answer 19

1. Viral particles are binding to their host cells
2. Viruses start making proteins, genomes, and assembling particles
3. Concentration of free viral particles drops (because they are attaching to bacteria)
4. Eventually, no free viruses can be detected

Question 20

What happens in the viral growth curve: rise period?

Answer 20

1. Burst of bacteriophage = bacterial cell lysis
2. A large amount of packaged viruses can be detected

Question 21

What happens in the lytic cycle?

Answer 21

bacteriophage quickly replicates, killing host cell

Question 22

What happens in the lysogenic cycle?

Answer 22

1. Bacteriophage is quiescent (not active)
2. Viral genome integrates into cell chromosome as a prophage (something that is before the phage)
3. Can reactivate to become lytic

Question 23

The decision between two cycles is dictates by _________

Answer 23

environment

Question 24

what type of events will trigger a lytic burst?

Answer 24

events that threaten host cell survival

Question 25

What are coliphages

Answer 25

phages that infect E. coli (T4 and lamba)

Question 26

T4 and lambda genome type and head?

Answer 26

double stranded linear DNA genome and both have capsid head

Question 27

T4 phage tail and what cycle for each?

Answer 27

T4 phage: contractile tail and lytic cycle (intemperate) lambda phage: non-contractile tail and lysogenic cycle (temperate)

Question 28

What are temperate phages

Answer 28

phages that maintain a stable relationship with the host cell in which they neither multiply nor are lost from the cell

Question 29

temperate phages are capable of _______

Answer 29

lysogeny

Question 30

How many lysogenic viruses of a particular type can be present in a host cell

Answer 30

only 1, immune to superinfection

Question 31

Induction of lytic Cycle is stimulated by what

Answer 31

1. DNA damage to host cell 2. UV light 3. Chemical mutagens 4. SOS response activated by DNA damage

Question 32

The SOS response activated by DNA damage initiates what

Answer 32

transcription of xis for excision of the prophage from the bacterial genome

Question 33

Why is host damage a signal for lysis?

Answer 33

a compromised host is less likely to be able to propagate and replicate the viral genome along with its own genome

Question 34

3 gene transfer processes and their explanations

Answer 34

Transformation: free DNA taken up from the environment Conjugation: cell-cell contact (sex pilus) Transduction: DNA transfer is mediated by virus that targets bacteria (bacteriophage)

Question 35

Explain transduction a bit

Answer 35

Transduction is the process in which bacteriophages carry DNA from one cell that has been infected to another cell * This occurs accidentally as an offshoot of the phage life cycle * Sometimes package bacterial DNA by mistake

Question 36

Are transducing particles active phage? (transducing particles are viruses carrying host DNA)

Answer 36

they may not be, as they may have incorporated only host DNA vs complete viral genomes.

Question 37

* In your bacteriophage lab, you will infect an E. coli strain containing a

Answer 37

plasmid that confers resistance to ampicillin

Question 38

* Some of the resulting phages in your lab will have packaged (randomly) this plasmid but not a complete viral genome, and they will be able to transduce new E. coli cells with this plasmid, and you can evaluate how this process worked by counting resulting:

Answer 38

ampicillin-resistant E. coli

Question 39

_______'s s work suggested that microbes could be the source of disease

Answer 39

Pasteur

Question 40

Koch proved what theory and what is it about

Answer 40

Germ Theory of Disease A specific type of microorganism causes a specific disease

Question 41

Koch's theory led to the isolation of

Answer 41

pure bacterial cultures

Question 42

Who developed the solid medium using agar

Answer 42

Angelina and Walther Hesse

Question 43

Who developed the double-dish container

Answer 43

Julius Petri

Question 44

* Growth on solid medium allows the isolation of

Answer 44

clonal (pure) cultures of bacteria

Question 45

Growth of microbes in pure culture: Each _______ or spot of bacterial growth represents the progeny of one original cell. Colonies are _______ – replicates of the _____ _____ that started the colony * Isolating colonies of bacteria and growth in broth allowed for isolation of clonal populations of bacteria in ______ ____

Answer 45

colony, clonal, original cell, pure culture

Question 46

What are 3 limitations of Koch's potulates

Answer 46

1. Slow-growing pathogens or pathogens may fail postulates 2. Pathogens may not be culturable with known techniques 3. The original host (e.g. human) is not always available for inoculation (Animal can be used as a host model)

Question 47

Considerations for choosing a host model (8)

Answer 47

Anatomical similarity to humans * Similar symptoms and courses of diseases * Similar bacterial distribution * Similar routes of transmission * Similar immune system * Inexpensive to obtain and maintain * Endangered species are not allowed * Genetic modification available?

Question 48

Most times, there are/are no perfect animal models for human diseases

Answer 48

are NO

Question 49

What is an epidemic

Answer 49

when a disease occurs in an unusually high number of individuals in a population at the same time

Question 50

What is a pandemic

Answer 50

is a worldwide epidemic (e.g. COVID-19

Question 51

What do epidemiologists do

Answer 51

study epidemics (or pandemics) and the factors that influence them

Question 52

What is quarantine

Answer 52

enforced isolation or restriction of free movement imposed to prevent the spread of contagious disease

Question 53

3 things that help in detection of a synthetic epidemic

Answer 53

* Clinical isolation/culturing of potential disease-causing microbes * Nucleic acid tests (i.e. PCR) for pathogens by presence of specific genes or genome sequences * Detection of microbial cells or microbial macromolecules

Question 54

Lecture 8

Answer 54

Lecture 8

Question 55

What is syntrophy?

Answer 55

a process where two or more microbes cooperate to catabolize a substance neither can catabolize by themselves

Question 56

In lab 12, there are _______ proteins (?) required to fully ________ a specific substance (1) to its end product (4). If the product is made, the bacteria will produce a pigment that is ____

Answer 56

3, (X Y Z), catabolize, red

Question 57

* But each of these three organisms also has a _________ in one of the genes – with each organism having a _________ in a different gene – making that protein product ____ ______

Answer 57

mutation, mutation, non-functional

Question 58

* If a bacterium can make the product when next to another bacterium providing _________, then that bacterium will turn red

Answer 58

intermediates