Bacterial structure

Question 1

What are bacteria?

Answer 1

single-celled organisms, prokaryotic cells

Question 2

How can bacteria exist?

Answer 2

as independent (free-living) or as parasites

Question 3

Do prokaryotes have a nucleus?

Answer 3

no

Question 4

Where is their genetic material stored?

Answer 4

in the nucleoid region in the cytoplasm; it’s protected and encased by the cell membrane

Question 5

Are eukaryotic cells bigger than prokaryotic cells?

Answer 5

yes

Question 6

Which has a cell wall?

Answer 6

prokaryotes

Question 7

What is the size range for bacteria?

Answer 7

0.2 to 2 um in diameter and 2 to 8 um in length

Question 8

What are the different shapes of bacteria?

Answer 8

spherical, rod shaped (bacillus), spiral

Question 9

How do spherical bacteria reproduce?

Answer 9

they remain attached to one another

Question 10

Define diplococci

Answer 10

cocci that remain in pairs after dividing

Question 11

Define streptococci

Answer 11

cocci that remain attached in a chain

Question 12

Define staphylococci

Answer 12

cocci that divide and form grapelike clusters

Question 13

How do rods reproduce?

Answer 13

Most divide only across their short axis and appear as single rods

Question 14

How do spiral bacteria reproduce (spirochetes)?

Answer 14

they have one or more twists and are NEVER straight.

Question 15

What is the size difference btw the different shaped bacteria?

Answer 15

cocci < bacilli < spirochete

Question 16

Name some structures external to the cell wall?

Answer 16

glycocalyx, flagella, fimbriae(pili)

Question 17

Define Monotrichous, lipotrichous, amphitrichous and peritrichous

Answer 17

Mono - 1 flagellum
Lipo - many flagella on 1 side
Amphi - 1 flagellum on each side
Peri - many flagella on both sides

Question 18

What do capsules look like under the microscope?

Answer 18

halos surrounding bacterium

Question 19

What structure impacts staining?

Answer 19

peptidoglycan

Question 20

What’s the difference btw the structure of gram + and gram - cell wall?

Answer 20

gram + has a thick layer of peptidoglycan and greatly cross-linked while gram - has a thin layer

Question 21

How does that reflect in staining?

Answer 21

gram + appears purple and gram - appears pink

Question 22

Do all bacteria have flagella?

Answer 22

no

Question 23

what are flagella used for?

Answer 23

attached to cell wall and provide motility

Question 24

What are characteristics of flagella?

Answer 24

composed of glycoproteins, highly immunogenic and are called H antigens

Question 25

What are fimbriae (pili)?

Answer 25

smaller protein appendages used for motility

Question 26

Are there more cilia or flagella?

Answer 26

cilia

Question 27

what can cilia help with?

Answer 27

attachment to host cells

Question 28

What are capsules?

Answer 28

outermost layer covering some bacteria, provide a "slime" covering; important virulence factors

Question 29

Do gram stains show capsules?

Answer 29

no, typically need special stains

Question 30

How do capsules help in pathogenesis?

Answer 30

1) disrupt phagocytosis 2) mediate attachment to host mucous layers 3) prevent dessication of the cell 4) resist lysis by complement 5) inhibit lysis within phagolysosomes

Question 31

What can several bacteria form?

Answer 31

spores

Question 32

What are spores?

Answer 32

resting stage that enables the organism to endure adverse conditions (for long period of time)

Question 33

What happens with spores when conditions improve?

Answer 33

spores transform into active bacteia

Question 34

Examples of spores that cause disease

Answer 34

anthrax, botulism and tetanus

Question 35

do all bacteria form spores?

Answer 35

no

Question 36

What is sterilization?

Answer 36

any process that effectively kills or eliminates transmissible agents from a surface, equipment, article of food or medication, or biological culture medium

Question 37

what does sterilization NOT remove?

Answer 37

prions

Question 38

How is sterilization achieved?

Answer 38

application of heat, chemicals, irradiation, high pressure or filtration

Question 39

Name 2 types of sterilization

Answer 39

dry and moist heat

Question 40

What does dry heat sterilization involve?

Answer 40

utilizes hot air; 320F for 2hrs or 340F for 1hr; destroys microorganisms by causing coagulation of proteins

Question 41

What is dry heat sterilization used for?

Answer 41

metal, glass and other solid material; UNSUITABLE for rubber and plastics

Question 42

What does moist heat sterilization involve?

Answer 42

utilizes hot air that is heavily laden with water vapor - moisture plays imp role; coagulates the proteins in organisms and aided by water vapor - high penetrating property --> death

Question 43

What is moist heat sterilization used for?

Answer 43

culture media, laboratory items and surgical equipment

Question 44

What is icineration used for?

Answer 44

destruction of infected carcasses; to kill spore-former bacteria, viruses

Question 45

What is gamma irradiation?

Answer 45

electromagnetic radiation of high frequency (short wavelength)

Question 46

What is gamma irradiation used for?

Answer 46

ionizing rays - sterilization of disposable plastic lab and surgical equipment; UNSUITABLE for glass and metal equipment

Question 47

What is UV light?

Answer 47

electromagnetic radiation with a shorter wavelength than that of visible light; non-ionizing rays with poor penetration

Question 48

What is UV light used for?

Answer 48

biosafety cabinets

Question 49

What is membrane filtration used for?

Answer 49

filtering out bacteria from heat sensitive fluids -serum, tissue culture media