Chapter 17 - Microorganisms, Viruses, Bacteria And Protist Flashcards
1
Q
What are microorganisms?
A
- unicellular
- microscopic
- prokaryotic or eukaryotic
- pathogenic
2
Q
What are some infectious agents?
A
- bacteria
- fungi
- protozoa
- viral
- prion
3
Q
What is a prion?
A
- infectious proteins
* transmissible spongiform encephalopathy
4
Q
What are the characteristics of life?
A
- structurally organized- order
- ability to acquire materials and energy
- ability to reproduce
- life comes from life - ability to respond to stimuli
- behavior - ability to maintain homeostasis
- “staying the same”
- maintaining relatively constant internal temperature - ability to grow and develop
- ability to adapt to the environment
- evolution- process by which a species changes over time resulting in increased adaption
5
Q
Viruses are not includes in the classification of organisms because…
A
- noncellular
- obligate intracellular parasites
- alive or not?
6
Q
What are the two parts to every virus?
A
- outer capsid - composed of protein subunits
- inner core -either DNA or RNA
- viral genome very small
7
Q
What do only some viruses have?
A
- spikes or attachment to host cell
- outer envelope
8
Q
Explain viral reproduction…
A
- specific to a particular host cell
- -must be able to attach
- once inside host cell, viral genome takes over the metabolic machinery of the host cell to make more viruses
9
Q
How can bacteriophages or phages reproduce?
A
- inside a bacterium
- lytic or lysogenic cycles
10
Q
Explain the steps of the lytic cycle..
A
- virus takes over immediately
- bacteria dies immediately after virus release
- 5 stages - attachment, penetration, biosynthesis, maturation, and release
11
Q
Explain the steps in the lysogenic cycle…
A
- phage lies latent until triggered to enter lytic cycle
- bacteria does not die until phage enters lytic cycle
- after attachment and penetration, phage integrates into host chromosome as a prophage
- trigger causes phage to enter lytic cycle biosynthesis, maturation and release
12
Q
Plant viruses…
A
- tend to enter through damaged tissues
- move through plasmodesmata
- tobacco mosaic virus
- until recently, the only way to control viruses was to destroy symptomatic plants and control insect vector (if there is one)
- with bioengineering, possible to transfer genes for disease resistance between plants
- -creation of transgenic papaya plants in Hawaii resistant to PRSV
13
Q
Animal viruses…
A
- reproduce similar to bacteriophages
- some,but not all, will have an outer membranous envelope beyond capsid
- -made from host cell plasma membrane
- herpesviruses (causes cold sores, genital herpes, and chickenpox in humans) are infectious that remain latent most of the time
- stress can cause them to enter lytic cycle
- retroviruses
- -RNA animal viruses with a DNA stage
- HIV - causes AIDS
- reverse transcriptase makes DNA from RNA template
14
Q
Emerging viruses…
A
- causative agent of a disease that only recently has infected large number of people.
- hiv, west nile virus, sars virus, hanta virus, ebola virus, bird flu virus… Etc.
- emerge in several ways
- transported to new location
- able to infect new species
- new mode of transmission
15
Q
Drugs…
A
- difficult to develop - use cell’s own machinery.
- some drugs structurally similar to nucleotides to interfere in viral genome synthesis.
- some block viral enzymes like reverse transcriptase in hiv
