Bio Ch 20

Question 1

Virus

Answer 1

associated with a number of plant, animal, and human diseases; biological enigma

Question 2

Capsid

Answer 2

all viruses have; composed of protein subunits and an inner core of nucleic acid (either DNA or RNA, but not both)

Question 3

Obligate intracellular parasites

Answer 3

viruses; can’t reproduce outside a living cell

Question 4

Bacteriophages (phages)

Answer 4

viruses that parasitize bacteria

Question 5

Lytic Cycle

Answer 5

5 stages: attachment, penetration, biosynthesis, maturation, & release

Question 6

Lysogenic Cycle

Answer 6

infecting phage does not immediately proliferate, but may do so sometime in the future; in the meantime, the phage is latent (not actively replicating)

Question 7

Prophage

Answer 7

while latent, the viral DNA is called this

Question 8

Lysogenic Cells

Answer 8

prophage is replicated along with the host DNA and all subsequent cells (called this) carry a copy of the prophage genome

Question 9

Retroviruses

Answer 9

animal viruses with an RNA genome that is converted into DNA within the host cell by a special enzyme called reverse transcriptase

Question 10

Reverse Transcriptase

Answer 10

special enzyme that converts an RNA genome into DNA within a host cell

Question 11

Emerging Viruses

Answer 11

new or previously uncommon illnesses caused by viruses that are able to infect large numbers of humans; AIDS, West Nile encephalitis, hantavirus pulmonary syndrome (HPS), severe acute respiratory syndrome (SARS), Ebola hemorrhagic fever, and avian influenza (bird flu)

Question 12

Viroids

Answer 12

naked strands of RNA (not covered by a capsid); causes crop diseases (potatoes, coconuts, citrus)

Question 13

Prions

Answer 13

proteinaceous infectious particles; cause a number of fatal brain diseases known as transmissible spongiform encephalopathies (TSE’s); proteins that normally exist in an animal, but have a different conformation/structure; cause infection by interacting with a normal protein and altering its structure

Question 14

Neurogenerative Diseases

Answer 14

TSE’s; those that destroy nerve tissue in the brain; ex = mad cow disease

Question 15

Prokaryotes

Answer 15

bacteria & archaea; fully functioning, living, single-celled organisms

Question 16

Flagella

Answer 16

some prokaryotes move by means of this; bacterial type has a filament composed of strands of the protein flagellin wound in a helix

Question 17

Fimbriae

Answer 17

short bristlelike fibers extending from the surface of many prokaryotes

Question 18

Nucleoid

Answer 18

dense area in a prokaryote where a single chromosome consisting of a strand of circular DNA is found

Question 19

Plasmids

Answer 19

many prokaryotes have accessory rings of DNA called this; can be extracted and used to carry foreign DNA into host bacteria during genetic engineering processes

Question 20

Binary Fission

Answer 20

prokaryotes reproduce asexually by means of this

Question 21

Conjugation

Answer 21

two bacteria temporarily linked together, often by means of a conjugation pilus; while linked, the donor cell passes DNA to a recipient cell

Question 22

Transformation

Answer 22

occurs when a cell picks up free pieces of DNA from its surrounding medium; this DNA has been secreted by live prokaryotes or released by dead ones

Question 23

Transduction

Answer 23

bacteriophages carry portions of DNA from one bacterial cell to another

Question 24

Bacteria

Answer 24

more common type of prokaryote

Question 25

Peptidoglycan

Answer 25

part of the cell wall of bacteria; = complex of polysaccharides linked by amino acids

Question 26

Gram-positive bacteria

Answer 26

single plasma membrane; thick peptidoglycan layer, stains dark purple

Question 27

Gram-negative bacteria

Answer 27

stains lighter purple or lacks purple color completely; peptidoglycan layer is sandwiched between 2 plasma membranes; this extra, outer membrane reduces the amount of Gram stain that binds to the peptidoglycan, so iodine-dye complex is washed away; 2nd dye (safranin) needed to stain bacteria pink so that it can be seen under a microscope

Question 28

Obligate Anaerobes

Answer 28

some bacteria are this; unable to grow in the presence of free oxygen

Question 29

Facultative Anaerobes

Answer 29

some bacteria are this; able to grow in either the presence or the absence of gaseous oxygen

Question 30

Photoautotrophs

Answer 30

photosynthetic; use solar energy to reduce CO2 to organic compounds

Question 31

Chemoautotrophs

Answer 31

carry out chemosynthesis; oxidize inorganic compounds such as hydrogen gas, hydrogen sulfide, and ammonia to obtain the necessary energy to reduce CO2 to an organic compound

Question 32

Chemoheterotrophs

Answer 32

take in organic nutrients

Question 33

Saphrotrophs

Answer 33

aerobic bacteria that decompose almost any large organic molecule into smaller ones that can be absorbed; AKA decomposers

Question 34

Symbiotic relationships

Answer 34

2 different species live together in an intimate way

Question 35

Mutualism

Answer 35

both species benefit from their association

Question 36

Commensalism

Answer 36

Only one species benefits while the other is unaffected

Question 37

Parasitism

Answer 37

one species benefits while harming the other

Question 38

Pathogens

Answer 38

parasitic bacteria that cause diseases

Question 39

Endospores

Answer 39

some of the deadliest pathogens form these when faced with unfavorable environmental conditions

Question 40

Toxins

Answer 40

in almost all cases, the growth of microbes themselves does not cause disease; the poisonous substances they release, called this, are the pathological portion

Question 41

Cyanobacteria

Answer 41

Gram-negative bacteria with a number of unusual traits; photosynthetic

Question 42

Lichens

Answer 42

cyanobacteria in association with fungi form these that can grow on rocks

Question 43

Archaea

Answer 43

at one time thought to be unique group of bacteria; in 1977, Woese and Fox discovered that the rRNA of archaea has a different sequence of bases than the rRNA of bacteria

Question 44

Methanogens

Answer 44

Methane makers; obligate anaerobes found in environments such as swamps, marshes, and the intestinal tracts of animals; chemoautotrophs; use H2 to reduce CO2 to methane (biogas)

Question 45

Halophiles

Answer 45

archaea that require high salt concentrations (usually 12 - 15%); use chloride pumps that use halorhodopsin to pump chloride to the inside of the cell to prevent water loss; aerobic chemoheterotrophs

Question 46

Thermoacidophiles

Answer 46

isolated from extremely hot, acidic environments, such as hot springs, geysers, submarine thermal vents, and around volcanoes; chemoautotrophic anaerobes; use hydrogen as electron donor and sulfur (or sulfur compounds) as terminal electron acceptors for their ETC's; H2S and protons (H+) are common products