Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 2 > CH. 19 Viruses > Flashcards

CH. 19 Viruses Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

cannot reproduce independently

A

infect every type of cell, including algae, bacteria, fungi, protozoa, plants and animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

seawater can contain 10 million viruses per milliliter

A

estimated 10^31 virus particles on earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

approximately 10 times the number of bacteria and archaea on earth

A

Miniscule, acellular infectious agents having either DNA or RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cause most of the diseases that plague the industrialized world

A

cannot carry out any metabolic pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Neither grow nor respond to the environment

A

Recruit the host cell’s metabolic pathways to increase their numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

No cytoplasmic membrane, cytosol, or organelles

A

Have extracellular and intracellular state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Not considered living due to the fact that they cannot reproduce but rather replicate. However they are not inert molecules by infectious molecules

A

Evolution of viruses most likely arose as bits of cellular nucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Plasmids and transposons or “jumping genes” serve as potential candidates for the source of viral genomes

A

plasmids, transposons and viruses are all mobile genetic elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Viruses infect cells and influence their genetic makeup

A

8% of the human genome contains sequences that come from viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

10 to 20% of bacterial DNA contains viral sequences

A

obligate intracellular parasites:
CANNOT multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

smallest infectious agents
smallest viruses: parvoviruses around 20 nm in diameter
Largest viruses: Herpes simplex virus around 150 nm in length
Pandoravirus~ 1 Micron
Megavirus ~680 nm

A

Viruses bear no resemblance to cells and lack machinery found in cells
The structure contains only those needed to invade and control a host cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Viruses exist as extracellular and intracellular state

A

Extracellular state called virion: a fully formed virus that is able to establish an infection in the host cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

protein coat (capsid) surrounding nucleic acid

A

Nucleic acid and capsid also called nucleocapsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Some have phospholipid envelope (enveloped vs. naked virus)

A

outermost layer provides protection and recognition site for host cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

intracellular state: capsid removed and virus exists as nucleic acid +

A

viral genomes may consist of either:
double or single stranded DNA
double or single stranded RNA
viruses are classified as either DNA or RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The genome of viruses are either single linear or circular molecule of the nucleic acid

A

viruses have between 3 and 2,000 genes in their genome

17
Q

For many years animal viruses were classified on the basis of their hosts and the diseases they caused

A

Newer classification systems emphasize the following when classifying viruses:

  • Hosts and diseases they cause
  • Structure
  • Chemical composition
  • Similarities in genetic makeup
18
Q

International committee on the taxonomy of viruses:

8 orders 38 families (another 84 families not yet assigned to any order)

A 
Most viral capsids come in two simple shapes\
Helical- rodlike or threadlike 
Icosahedral -generally spherical 
viral morphology is highly diverse:
Naked viruses (poliovirus)
some virsues are complex 
poxiviruses- multilayered capsid 
T-even bacteriophages - binal (two fold) symmetry 
enveloped virsues (influenza)
19
Q

Viruses are obligate intracellular parasites in every kind of organism investigated

A

Host range:
Each type of virus has a limited host range
Tissue tropism- inside a host the virus may only infect certain tissues
Viruses can remain dormant or latent for years ex. chicken pox can reemerge as shingles
More kinds of viruses exists than kinds of organisms

20
Q

Viral replication #1
Viral tricks host genome into making new viruses
cell with a virus is often damaged with infection
viruses can only reproduce inside cells
outside, they metabolically inert virions

A

Viral replication #2
Viruses lack their own ribosomes and enzymes for protein and nucleic acid synthesis
virus hijacks the cell’s transcription and translation machineries to express
End result is assembly and release of viruses

21
Q

viral infections: persistent vs. acute
categorized based -
How rapid or frequent it is produced
appearance of associated symptoms

A

persistent infections-latent or chronic
acute infections-rapid replication of virus and can lead to sudden symptom onset
can cause outbreaks, epidemics and pandemics

22
Q

Influenza
One of the most lethal viruses in human history
Influenza pandemic of 1918 and 1919 thought to have infected 1/3 of the world’s population
flu viruses are enveloped animal viruses

A 
Influenza 
3 "types" based on capsid protein 
-Type A -serious epidemics in humans and other animals 
- Types B and C - mild human infections 
subtypes differ in protein spikes 
-Hemagglutinin (H)-aids in viral entry 
-Neuraminidase (N)-aids in viral exit
23
Q

Antigenic drift and shift
H and N molecules accumulate random mutations
-thus we have annual flu shots and not a single vaccine
-antigenic shift produces strains of virus with novel combinations of HA and NA

A 
Spanish flu of 1918, A (H1N1)
-killed 50- 100 million worldwide
-Asian flu of 1957, A (H2N2)
-killed over 100,000 Americans
Hong Kong flu of 1968, A (H3N2)
24
Q

Human immunodeficiency virus
HIV causes acquired immune deficiency syndrome (AIDS)
HIV infection is Chronic
HIV infects and ultimately destroys certain types of immune cells
Without CD4+ cells and helper T cells the body cannot mount an effective immune response
Host may ultimately die from a variety of opportunistic
infections
-do not normally cause disease

A

Evolution of HIV
During an infection, HIV is constantly replicating and mutating
Eventually virus mutates to infect a broader range of cells, leading to a loss of T-Helper cells
Destruction of T cells block the body’s immunity response to opportunistic infections and cancer

25
Q

Latent viral infections
Virsues that “hide” within the host to evade the immune system can establish lifelong latent infections
-HSV-1 and HSV-2 trigger acute disease episodes and then become latent inside neurons
physiological stimuli can trigger their reactivation and lead to additional disease episodes
some latent viruses do not become incorporated into host chromosome
-incorporation of provirus into host DNA is permanent
-provirus: viral DNA incorporated into the DNA host

A

Viral role in Cancer:
-viruses cause 20 -25% of human cancers
-some carry copies of oncogenes as part of their genomes
-some promote oncogenes already present in the host
-some interfere with tumor repression
specific viruses are known to cause ~15% of human cancers
-Burkitt’s lymphoma
-Hodgkin’s disease
-Kaposi’s sarcoma
-cervical cancer
Transformation: the effect of oncogenic or cancer causing viruses
oncoviruses: mammalian viruses capable of imitating tumors

26
Q 
Viruses that infect Bacteria 
Bacteriophage "bacteria eating"
 Viruses that infect bacteria 
The bacteria they infect are often more pathogenic for humans 
diverse and only by bacterial hosts 
called phage for short 
E.coli infecting viruses are the best studied
viruses have also been found in archaea
A

Replication of phages
Phages have two alternative reproductive mechanisms the lytic cycle and the lysogenic cycle
Lytic: produces new phages and lyses (breaks open) the host’s cell wall, releasing the progeny (virulent phage)
Lysogenic: Viral DNA molecule is incorporated into the host cell’s chromosome (prophage)
-does not kill host cell
Temperate phages: use both the lytic and lysogenic
cycles
-commonly use λ in biology research
-Bacterial defense-restriction enzymes

27
Q

Prions-
“Proteinaceous infectious particles”
Cause transmissible spongiform encephalopathies (TSE’s)
-Mad cow disease
-scrape in sheep
-Creutzfeldt-Jakob disease in humans (CJD)
Host has normal prion proteins (PrP^c)
Misfolded proteins (PrP^sc) causes normal PrP to misfold, causing disease

A

Viroids
Tiny naked molecules of circular RNA
Cause diseases in economically important crops
use host protein to replicate
small interfering RNA’s (siRNAs) may be produced during infection
-interfering with plant growth and development

28
Q

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

A

Genetic material composed of nucleic acid

29
Q

What is the name given to a virus that attacks a bacterium?

A

Phage

30
Q

Which of the following processes does HIV use to synthesize a DNA strand using its RNA genome as a template?

A

Reverse transcription

31
Q

What is the most effective way to stop viral infections?

A

vaccines

32
Q

The H1N1 2009 outbreak is considered to have been ?

A

A pandemic

Biology 2 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions