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Bacteriology > Bacterial structure > Flashcards

Bacterial structure Flashcards

1
Q

What are bacteria?

A

single-celled organisms, prokaryotic cells

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2
Q

How can bacteria exist?

A

as independent (free-living) or as parasites

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3
Q

Do prokaryotes have a nucleus?

A

no

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4
Q

Where is their genetic material stored?

A

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

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5
Q

Are eukaryotic cells bigger than prokaryotic cells?

A

yes

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6
Q

Which has a cell wall?

A

prokaryotes

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7
Q

What is the size range for bacteria?

A

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

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8
Q

What are the different shapes of bacteria?

A

spherical, rod shaped (bacillus), spiral

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9
Q

How do spherical bacteria reproduce?

A

they remain attached to one another

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10
Q

Define diplococci

A

cocci that remain in pairs after dividing

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11
Q

Define streptococci

A

cocci that remain attached in a chain

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12
Q

Define staphylococci

A

cocci that divide and form grapelike clusters

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13
Q

How do rods reproduce?

A

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

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14
Q

How do spiral bacteria reproduce (spirochetes)?

A

they have one or more twists and are NEVER straight.

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15
Q

What is the size difference btw the different shaped bacteria?

A

cocci < bacilli < spirochete

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16
Q

Name some structures external to the cell wall?

A

glycocalyx, flagella, fimbriae(pili)

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17
Q

Define Monotrichous, lipotrichous, amphitrichous and peritrichous

A

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

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18
Q

What do capsules look like under the microscope?

A

halos surrounding bacterium

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19
Q

What structure impacts staining?

A

peptidoglycan

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20
Q

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

A

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

21
Q

How does that reflect in staining?

A

gram + appears purple and gram - appears pink

22
Q

Do all bacteria have flagella?

A

no

23
Q

what are flagella used for?

A

attached to cell wall and provide motility

24
Q

What are characteristics of flagella?

A

composed of glycoproteins, highly immunogenic and are called H antigens

25
Q

What are fimbriae (pili)?

A

smaller protein appendages used for motility

26
Q

Are there more cilia or flagella?

A

cilia

27
Q

what can cilia help with?

A

attachment to host cells

28
Q

What are capsules?

A

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

29
Q

Do gram stains show capsules?

A

no, typically need special stains

30
Q

How do capsules help in pathogenesis?

A

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

31
Q

What can several bacteria form?

A

spores

32
Q

What are spores?

A

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

33
Q

What happens with spores when conditions improve?

A

spores transform into active bacteia

34
Q

Examples of spores that cause disease

A

anthrax, botulism and tetanus

35
Q

do all bacteria form spores?

A

no

36
Q

What is sterilization?

A

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

37
Q

what does sterilization NOT remove?

A

prions

38
Q

How is sterilization achieved?

A

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

39
Q

Name 2 types of sterilization

A

dry and moist heat

40
Q

What does dry heat sterilization involve?

A

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

41
Q

What is dry heat sterilization used for?

A

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

42
Q

What does moist heat sterilization involve?

A

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

43
Q

What is moist heat sterilization used for?

A

culture media, laboratory items and surgical equipment

44
Q

What is icineration used for?

A

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

45
Q

What is gamma irradiation?

A

electromagnetic radiation of high frequency (short wavelength)

46
Q

What is gamma irradiation used for?

A

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

47
Q

What is UV light?

A

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

48
Q

What is UV light used for?

A

biosafety cabinets

49
Q

What is membrane filtration used for?

A

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

Bacteriology (2 decks)

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