Bacterial structure

Question 1

what 3 organelles do prokaryotic cells lack

Answer 1

• golgi
• ER
• nucleus

Question 2

genetic material in prokaryotic cells

Answer 2

nucleoid region enclosed in a cell membrane

Question 3

2 examples of prokaryotes

Answer 3

• bateria

- cyanobacteria

Question 4

how much bigger are eukaryotes than prokaryotes

Answer 4

10x bigger

Question 5

3 bacterial shapes

Answer 5

• coccus
• bacillus
• spirochete

Question 6

cocci info (post-division)

Answer 6

• 2 = diplococci
• chain = streptococci
• cluster = staphlococci

Question 7

how do most bacilli divide and appear

Answer 7

• divide across their short axis

- appear as single rods

Question 8

3 external structures in bacteria

Answer 8

• glycocalyx
• flagella
• fimbriae (pilli)

Question 9

what is glycocalyx

Answer 9

a coating or layer of molecules external to the cell wall –> protective, adhesive, and receptor functions

Question 10

4 types of flagella

Answer 10

• monotrichoid (1)
• lopotrichois (multiple out one end)
• amphitrichous (1 out each end)
• peritrichious (many all over)

Question 11

gram + versus gram - structure

Answer 11

• positive: thick peptidoglycan layer (single membrane –> monoderms)
• negative: thin peptidoglycan layer, periplasmic space (double membrane –> diderms)

Question 12

steps in a gram stain

Answer 12

• fixation
• crystal violet
• iodine
• alcohol decolorizer
• safranin

Question 13

gram + in a gram stain

Answer 13

• picks up crystal violet
• gets lighter but not decolorized
• stays purple

Question 14

gram - in a gram stain

Answer 14

• picks up crystal violet
• gets lighter with iodine
• decolorized
• picks up safranin
• turns red

Question 15

flagella info

Answer 15

• can have any or none
• attached to the cell wall
• provide motility
• composed of glycoproteins
• highly immunogenic
• used for serotyping
• called H antigens

Question 16

fimbriae (pili)

Answer 16

• smaller protein appendages
• present in higher number on a cell
• not used for motility
• can participate in attachment to host cells

Question 17

capsules

Answer 17

• outermost layer covering some bacteria
• not easily viewed under gram stain (need india ink or CuSO4)
• virulence factors –> phagocytosis, attachment, desiccation, lysis

Question 18

spores

Answer 18

• resting stage that enables organism to endure harsh conditions
• transform into active bacteria when conditions improve
• not all bacteria can form spores

Question 19

methods of sterilization (5)

Answer 19

• heat
• chemicals
• irradiation
• high pressure
• filtration

Question 20

heat sterilization

Answer 20

• dry heat: coagulates proteins (metal, glass, other solid materials)
• moist heat: coagulates proteins, high penetrating property (culture media, lab items, surgical equipment)

Question 21

incineration

Answer 21

for infected carcasses

Question 22

gamma irradiation

Answer 22

• electromagnetic radiation
• disposable plastic lab and surgical equipment
• not for glass or metal

Question 23

UV light sterilization

Answer 23

• electromagnetic radiation

- used in biosafety cabinets

Question 24

membrane filtration

Answer 24

used for filtering out bacteria from heat sensitive fluids such as serum, tissue culture media