microbiology (guest lec)

Question 1

eukaryote cell wall:

Answer 1

• cellulose

- chitin

Question 2

bacterial cell wall:

Answer 2

peptidoglycan

- network of sugar polymers cross-linked by polypeptides

Question 3

archeal cell walls:

Answer 3

polysaccharides and proteins

- no peptidoglycan

Question 4

Gram staining: features

Answer 4

• bacterial groups classified based on cell wall composition
• gram negative: less peptidoglycan, outer membrane (pink/ red- red safranin dye)
• gram positive: thick cell wall of peptidoglycan (purple- crystal violet)

Question 5

Gram staining: process

Answer 5

• stained with crystal violet and iodine
• rinsed in alcohol
• stained with red dye (safranin)

Question 6

capsule:

Answer 6

• some prokaryotes make polysaccharide or protein layer

Question 7

fimbriae:

Answer 7

hair like appendages for adherence or motility

Question 8

sex pili:

Answer 8

longer than fimbriae

- allow prokaryotes to exchange DNA

Question 9

motility: and taxis

Answer 9

• most commonly use flagella

- taxis: ability to move toward/ away from certain stimuli

Question 10

reproduction:

Answer 10

• binary fission

- divide every 1-3 hrs

Question 11

endospores:

Answer 11

most prokaryotes form metabolically inactive endospores which remain viable in harsh conditions for centuries

Question 12

factors contributing to genetic diversity:

Answer 12

• rapid reproduction
• mutation
• genetic recombonitation

Question 13

prokaryotes: rapid reproduction

Answer 13

via binary fission

- although generally identical

Question 14

prokaryotes: mutation rates

Answer 14

• low due to binary fission

- however rapid reproduction (short generation times) accumulate mutations rapidly in population

Question 15

prokaryotes: high diversity

Answer 15

• from mutations allows for rapid evolution

Question 16

prokaryotes: genetic recombination and eg.

Answer 16

• transformation
• transduction
• conjugation

Question 17

transformation:

Answer 17

prokaryotic cell take up foreign DNA from surrounding environment

Question 18

transduction:

Answer 18

movement of genes btw bacteria by bacteriophages (viruses which infect bacteria)

Question 19

conjugation: and eg.

Answer 19

transfer of DNA btw cells from direct cell-to-cell contact (sex pili)
- eg. F plasmid of E.coli

Question 20

R plasmid:

Answer 20

carry genes for antibiotic resistance

Question 21

phototrophs:

Answer 21

obtain energy from light

Question 22

chemotrophs:

Answer 22

obtain energy from chemicals

Question 23

autotrophs:

Answer 23

require CO2 as carbon source

Question 24

heterotrophs:

Answer 24

require organic nutrient to make organic compounds

Question 25

obligate aerobes:

Answer 25

• prokaryotes which require O2 for cellular respiration

Question 26

obligate anaerobes:

Answer 26

• prokaryotes which are poisoned byO2 and use fermentation or anaerobic respiration

Question 27

facultative anaerobes:

Answer 27

• prokaryotes which can survive with or without O2

Question 28

nitrogen fixation:

Answer 28

• some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)
• they can make nitrogen available to plants

Question 29

metabolic cooperation: and eg

Answer 29

• cooperation btw prokaryotes allows them to use environmental resources they could not use as individual cells
• eg. biofilm of dental plaque made of numerous bacterial species

Question 30

chemical recycling:

Answer 30

• chemoheterotrophs (decomposers)

- nitrogen-fixing prokaryotes add usable nitrogen to environment

Question 31

mutualism:

Answer 31

both organisms benefit

Question 32

commensalism:

Answer 32

one organism benefits, while neither harming/helping other significantly

Question 33

parasitism:

Answer 33

parasite harms but does not kill host

Question 34

pathogens:

Answer 34

parasites that cause disease

• only bacteria
• produce toxins (exotoxins/ endotoxins)