Bacterial Shapes

Question 1

What is the name for cocci that remain in pairs after dividing?

Answer 1

Diplococci.

Question 2

What is the name for cocci that divide and remain attached in a line?

Answer 2

Streptococci.

Question 3

What is the name for cocci that divide and form grapelike clusters?

Answer 3

Staphylococci.

Question 4

What is a common bacteria that is spiral-shaped?

Answer 4

Spirochetes.

Question 5

How do most bacilli divide?

Answer 5

Across their short axis.

Question 6

How do most bacilli appear (as compared to cocci)?

Answer 6

As single rods.

Question 7

How many twists do spiral bacteria have?

Answer 7

One or more twists. They are NEVER straight.

Question 8

What three non-essential appendages can bacteria have any or none of?

Answer 8

1) Glycocalyx (capsules).
2) Flagella.
3) Fimbriae (fimbriae).

Question 9

What is glycocalyx and what is its function?

Answer 9

Glycocalyx is a coating or layer of molecules external to the cell wall. It serves protective, adhesive, and receptor functions.

Question 10

What are flagella?

Answer 10

A flagellum is a lash-like appendage that protrudes from the cell body used in locomotion.

Question 11

What is the term for having one flagellum?

Answer 11

Monotrichous.

Question 12

What is the term for having two or more flagella at one end?

Answer 12

Lopotrichous.

Question 13

What is the term for having flagella at each end of the bacterium?

Answer 13

Amphitrichous.

Question 14

What is the term for having flagella around the entire surface of the bacterium?

Answer 14

Peritrichous.

Question 15

What are fimbriae?

Answer 15

A fimbria is an appendage composed of curlin proteins that is thinner and shorter than a flagellum. It is used by bacteria to adhere to one another and to adhere to animal cells and some inanimate objects.

Question 16

How can you differentiate Gram positive and Gram negative bacteria by their membranes?

Answer 16

Gram-positive bacteria are monoderms, only having a simple cytoplasmic membrane. Gram-negative bacteria are diderms, having double-membrane envelopes.

Question 17

What is the name of the protein in both Gram positive and negative bacteria that is essential for their survival?

Answer 17

Peptidoglycan.

Question 18

How does the peptidoglycan layer differ between Gram positive and Gram negative bacteria?

Answer 18

Gram + bacteria have a peptidoglycan layer which is much thicker and more highly cross-linked than a Gram - organism.

Question 19

What colors do Gram + and - bacteria stain with Gram stain?

Answer 19

Gram-positive = purple.
Gram-negative = reddish-pink.

Question 20

What allows the crystal violet during Gram staining wash out during decolorization for Gram negative bacteria?

Answer 20

The Gram negative peptidoglycan layer is thin and not greatly cross-linked unlike the Gram positive peptidoglycan layer.

Question 21

What are the four substances used for Gram staining (list in order of use)?

Answer 21

1) Crystal violet.
2) Iodine (mordant).
3) Alcohol (decolorization).
4) Safranin (counterstain).

Question 22

What are flagella composed of?

Answer 22

Glycoproteins.

Question 23

True or false. Flagella are highly immunogenic.

Answer 23

True.

Question 24

True or false. Flagella are used for serotyping and are called M antigens.

Answer 24

False. Flagella ARE used for serotyping, but they are called H antigens.

Question 25

True or false. Fimbriae are larger than flagella.

Answer 25

False. Fimbriae are smaller protein appendages.

Question 26

What are present in higher numbers on a cell? Flagella or fimbriae?

Answer 26

Fimbriae.

Question 27

Which appendage is used for motility? Flagella or fimbriae?

Answer 27

Flagella. Fimbriae can participate in attachment to host cells.

Question 28

What is a capsule?

Answer 28

A capsule is the outermost layer covering certain bacteria and provides a "slime" covering.

Question 29

True or false. Capsules are easily viewed under Gram's stain.

Answer 29

False. Capsules are NOT easily viewed under Gram's stain. Special stains (India ink or CuSO4) are used instead.

Question 30

What are five virulence factors associated with capsules?

Answer 30

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

Question 31

What is a spore, or endospore?

Answer 31

A spore is the resting stage of some bacteria that enables the organism to endure adverse conditions.

Question 32

What are three diseases that are caused by spores?

Answer 32

1) Anthrax. 2) Botulism. 3) Tetanus.

Question 33

True or false. All bacteria can form spores.

Answer 33

False. Not all bacteria can form spores.

Question 34

What is sterilization?

Answer 34

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

Question 35

What does sterilization kill? What does it not remove?

Answer 35

Sterilization kills bacteria, viruses, spore forms, etc. Sterilization does not, however, remove prions.

Question 36

What are five ways sterilization can be achieved?

Answer 36

1) Heat. 2) Chemicals. 3) Irradiation. 4) High pressure. 5) Filtration.

Question 37

What are the two types of heat sterilization?

Answer 37

1) Dry heat sterilization. | 2) Moist heat sterilization.

Question 38

What does dry heat sterilization utilize?

Answer 38

Hot air.

Question 39

What is the proper time and temperature for dry heat sterilization?

Answer 39

1) 320F for 2 hours. | 2) 340F for 1 hour.

Question 40

How does dry heat destroy microorganisms?

Answer 40

Dry heat destroys microorganisms by causing coagulation of proteins.

Question 41

What materials can it be used on? Not used on?

Answer 41

Dry heat can be used for sterilizing metal, glass, and other solid material. It is unsuitable for rubber and plastics.

Question 42

How does moist heat sterilization work?

Answer 42

Moist heat utilizes hot air that is heavily laden with water vapor and where this moisture plays the most important role in the process of sterilization.

Question 43

Why is the water vapor in moist heat sterilization important?

Answer 43

The water vapor has a very high penetrating property, leading to the organism's death.

Question 44

What is moist heat used to sterilize?

Answer 44

It is used for sterilizing culture media, laboratory items, and surgical equipment.

Question 45

What is used for the destruction of infected carcasses?

Answer 45

Incineration.

Question 46

What temperature needs to be reached to incinerate a carcass?

Answer 46

1000 C.

Question 47

True or false. Bacteria, including, spore-formers, and viruses will not survive incineration.

Answer 47

True.

Question 48

What is gamma radiation?

Answer 48

Gamma radiation, also known as gamma rays, is electromagnetic radiation of high frequency (very short wavelength).

Question 49

What is ionizing rays used for to sterilize?

Answer 49

Ionizing rays are used for sterilization of disposable plastic lab and surgical equipment.

Question 50

What is gamma irradiation unsuitable for?

Answer 50

It is unsuitable for glass and metal equipment.

Question 51

What is ultraviolet light?

Answer 51

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, or non-ionizing rays with poor penetration.

Question 52

What is UV light used for?

Answer 52

It is used in biosafety cabinets.

Question 53

What is membrane filtration used for?

Answer 53

It is used for filtering out bacteria from heat sensitive fluids such as serum and tissue culture media.