Unit 4 Part 5 Viruses: Basic Structures and Functions

Question 1

what is virology

Answer 1

the study of viruses

Question 2

unlike other microganisms (such as bacteria, fungi, and protozoa) viruses are

Answer 2

acellular infectious agents

obligate intracellular parasites

Question 3

are viruses able to metabolize, generate energy, and multiply independently

Answer 3

no

Question 4

what is meant by the term obligate intracellular paraistes

Answer 4

they must enter a suitable host in order to propogate

Question 5

outside of a host cell viruses are

Answer 5

inert

Question 6

true or false: viruses are bigger than microbes

Answer 6

false

Question 7

what unit are viruses measured in

Answer 7

nanometers

Question 8

what is the size range of viruses pathogenic to humans

Answer 8

20 - 300nm

Question 9

what are two characteristics of structure every virus has

Answer 9

a capsid

viral genome: RNA or DNA (not both)

Question 10

some viruses have extra structural components such as

Answer 10

replication enzymes
envelope
glycoprotein spikes

Question 11

what 3 ways are viruses classified

Answer 11

1. based on their (genome) nucleic acid types
2. the presence or absence of an envelope
3. capsid symmetry

Question 12

what is viral capsid and what is its purpose

Answer 12

a protein coat enclosing and protecting the viral genome and replication enzymes from degradation

Question 13

what is a viral capsid made up of

Answer 13

individual and identical protein subunits called capsomers

Question 14

what can capsomers do during viral replication

Answer 14

spontaneously self-assemble into the capsid

Question 15

capsomers can be assembled and arranged into precise patterns in the capsid to form two final shapes. what are they

Answer 15

1. helical (symmetry)

2. icosahedral

Question 16

in helical viruses if you were to cut the capsid into two what would you find

Answer 16

the two halves are identical to each other

Question 17

helical viruses capsomers fit together as either a _____ or _____

Answer 17

spiral or helix

Question 18

how do helical viruses often appear under an electron microscope

Answer 18

as rod-shaped

Question 19

what are 3 examples of helical viruses

Answer 19

measles
mumps
influenza

Question 20

how many sides does a icosahedral virus have

Answer 20

20 sided

Question 21

what does each side of a icosahedral consist of regarding capsomers

Answer 21

21 identical capsomers arranged in the shape of a equilateral triangle

Question 22

capsids of icosahedral viruses may allow what to attach to the host cell receptors

Answer 22

naked viruses

Question 23

where is the viral genome packaged in icosahedral viruses

Answer 23

inside the capsid

Question 24

the viral genome inside the capsid or a icosahedral virus is known as what

Answer 24

nucleocapsid

Question 25

what is the viral envelope made of

Answer 25

proteins and host cell membrane (phospholipids) that enclose the nucleocapsid

Question 26

is the viral envelope found in all viruses

Answer 26

no, only some

Question 27

what can the viral envelope have on it

Answer 27

surface projections called glycoprotein spikes

Question 28

what do glycoprotein spikes on a viral envelope allow for

Answer 28

attachment to specific host cell surface receptors | facilitate the release of newly created mature viruses from infected cells

Question 29

enveloped viruses are more susceptible to what then naked viruses

Answer 29

chemical biosides such as alcohol

Question 30

what is a notable virus with a viral envelope that contains glycoprotein spikes

Answer 30

HIV

Question 31

in the HIV virus what does the glycoprotein spike do

Answer 31

gp120 binds to CD3 receptor on T helper lymphocytes in humans

Question 32

How many types of glycoprotein spikes does influenza virus have

Answer 32

2 hemaglutinin (aka H or HA spikes) Neuraminidase spikes (N or NA)

Question 33

what is the role of the hemagglutinin (aka H or HA) spikes in the influenza virus

Answer 33

spikes attach to the receptor sialic acid on cells in the respiratory tract

Question 34

what is the role of the neuraminidase (N or NA) spikes in the influenza virus

Answer 34

cleave and release the viral progeny from the infected cell to promote spreading

Question 35

how many types of influenza virus are there

Answer 35

2 Type A and type B

Question 36

Type A influenze can be classified into subtypes based on what

Answer 36

according to the H and N spikes

Question 37

how many strains does the 2016-2017 vaccine contain

Answer 37

3

Question 38

different H spikes on the influenza virus determine what

Answer 38

host specificity and range

Question 39

what subtypes are the most common caues of human flu

Answer 39

H1, H2 & H3

Question 40

whats the difference between the swine flu and the avian flu regarding receptors

Answer 40

swine flu: H1 receptors bind to cells in the upper respiratory tract avian flu: H5 tends to bind to cells in the human lungs

Question 41

what has limited transmission between humans between swine flu and avian flu

Answer 41

swine flu is more contagious because they latch in the upper respiratory tract

Question 42

true or false: some viruses carry replication enzymes with them

Answer 42

true

Question 43

what is an example of a virus that carries replication enzymes

Answer 43

HIV | carries: reverse transcriptase and protease (targeted by antiviral drugs)

Question 44

can viruses contain both DNA and RNA

Answer 44

no, one or the other

Question 45

true or false the virus genome is single stranded

Answer 45

false, viral genome can either be single stranded or double stranded i.e. ssDNA, ssRNA, dsDNA or dsRNA

Question 46

the type of DNA or RNA and its polarity of the viral genome can influence what

Answer 46

how they multiply in the host cell

Question 47

what does the coronavirus cause

Answer 47

sars and the common cold