Unit 6 Flashcards
Why aren’t viruses considered alive?
They do not reach all the characteristics of a living thing
Which characteristics of living things (REACH N GO) do they NOT have
● Reproduce (they replicate) ● use Energy ● made of Cells ● maintain Homeostasis ● Grow (instead they assemble) ● not Organized
What characteristics of living things DO they have
● Adapt / Evolve
● contain Nucleic Acids (DNA/RNA)
What are the two general parts of a virus?
a) Nucleic Acid (DNA or RNA)
b) Protein capsid/coat
What are the protein projections that stick out from a virus used for?
Antigens (proteins) that act as Keys used to unlock and enter/infect a cell.
Explain a lysogenic infection
Lysogenic infection (HIV), occurs when a virus infects a cell but the cell does not show symptoms and is generally unharmed. The cell continues to live and divide, each time continuing to replicate the viral DNA
If you start feeling ill from a virus, what type of infection do you have and why?
One begins to feel ill or show symptoms once a
Lytic infection begins because your cells are being
ruptured/destroyed (lysed) each time millions of
copies of the virus are released
Why can’t an antibiotic be given to someone ill with a viral infection?
Viruses are not alive therefore they cannot be “killed”. Antibiotics work by damaging
living bacteria cells. Since a virus is not a cell, antibiotics are not effective.
What are the characteristics of bacteria and what basic cell type are they considered?
Prokaryotic cells: simple, do not have a nucleus or complex organelles
Contain a Cell Wall, can be either heterotrophic or a variety of forms of autotrophic
What are 3 general ways bacteria can be grouped together and what are the prefixes for this terminology?
a) Staphylo = clusters
b) Diplo = pairs
c) Strepto = chains
What are the 3 general shapes of bacterial cells?
a) Bacilli = Rod shaped
b) Spirilla = Spiral shaped
c) Cocci = Sphereshaped
Explain WHY bacteria are able to live nearly everywhere
Bacteria are the smallest living cells, contain a rigid cell wall, can form endospores under extreme conditions,
and some can survive without oxygen.
What is the role of bacteria in the ecosystem?
Decomposers – recycle energy, producers (oxygen), nitrogen fixers
What are the three ways in which bacteria reproduce or exchange genetic material?
a) Binary Fission simple cell division of prokaryotic cells
b) Conjugation linking together to exchange genetic information
c) Endospore formation forming a nearly indestructible barrier in order to
survive harsh environmental conditions
During what type of conditions would bacteria begin to form endospores?
Harsh environmental conditions (drought, lack of food, toxins) causing the bacteria
species to die off.
Why/How do bacteria harm us?
a) Deprive cells of nutrients (starve our cells) and secrete enzymes that break down tissue
b) Poison our cells by releasing toxins as waste. (endotoxins and exotoxins)
What are the two general ways in which antibiotics kill bacteria?
a) Tear down cell walls
b) Disrupt formation of DNA / Inhibit protein synthesis (cellular processes)
Which antibiotic worked the best in the picture above and how did you determine
your answer? (Underline the phrase, “Zone of Inhibition” in your answer)
Antibiotic A was the most effective because it has the largest zone of inhibition, which is the area around the
antibiotic disc where bacteria has been killed.
How do we know that bacteria continually evolve? (Hint: Why must we keep formulating new antibiotics?)
Bacteria continue to evolve ways of becoming resistant to antibiotics. As their DNA mutates they are able to
be less affected by the ways in which the antibiotics work against them.
Macrophage
Engulf pathogens
B-Cell
Produce antibodies
Killer T-cell
Target and destroy body cells that have been infected
Memory cells
WBCs that recognize the antigens on pathogens
Antibodies
Bind to the antigens, mark for destruction and/or render ineffective
