Module 2: Bacterial Anatomy

Question 1

What is cellular morphology?

Answer 1

When bacteria is examined under the microscope for shape, size and arrangement.

Question 2

What measurement is used to bacteria?

Answer 2

Micrometer. 1micrometer= 1000mm = 1x10-6 m

Question 3

What are the three basic shapes of bacteria?

Answer 3

1. Cocci (coccus) - ball shaped (size 1um X 1um)
2. Bacilli (bacillus) - rods (size average 0.5um X 3um)
3. Spirilla (spirillum or spirochetes). - spiral shaped rods.

Question 4

What are cocci chains?

Answer 4

Bacteria cells divide in one plane only and adhere to each other after division. Eg. streptococci

Question 5

What are cocci clusters?

Answer 5

When bacteria divide in several planes and adhere to each other to form grape like clusters. Eg. Staphylococci

Question 6

What are diplococci?

Answer 6

Cocci that are arranged in pairs.

Question 7

What are cocci tetrads and sarcinae?

Answer 7

Cocci that divide in two planes at right angles to each other to groups of four.
AND
Cocci that divide in three planes at right angles to each other to groups of eight - like grapes.

Question 8

What are four different shapes that rods are?

Answer 8

1. Rounded rods
2. Square rods
3. Pointed ends
4. Short, oval coccoid rods are also called coccobacilli- look like rice grains.

Question 9

Describe the rod-shaped bacteria arrangement palisades?

Answer 9

Bacteria that divide and sheet (on top of each other).

Question 10

Describe the rod-shaped bacteria arrangement acute angles?

Answer 10

Bacteria snaps at point of division.

Question 11

Define involution forms.

Answer 11

Dead, degenerating or dying bacteria. Happens from lack of nutrients or proper atmospheric conditions for growth or antibiotic treatment.

Question 12

What is flagella?

Answer 12

Long filamentous appendages that allow movement 0.02 micrometers (not shown on gram stained slides). Gives bacteria moving patterns.
Flagella are found on some rods, but not on cocci.

Question 13

What are the five flagellar arrangements?

Answer 13

Atrichous: No flagella

Monotrichous: Single flagellum on one end of bacteria (very directional movement)

Lophotrichous: Tuft of flagella on one end of bacteria (very directional movement)

Amphitrichous: Tufts of flagella on both ends of bacterial cell (spinning motion)

Peritrichous: Flagella all around bacterial cell (spinning motion)

Question 14

What is slide motility of flagella?

Answer 14

When an organism is grown in pure culture in a liquid, once in log phase (actively motile) of growth a drop is looked at under 40X on microscope.

Question 15

What is brownian movement of flagella?

Answer 15

molecules bombard bacterial cells and they appear to jiggle or vibrate.

Question 16

What is drifting or streaming of flagella?

Answer 16

when everything flows in one direction.

Question 17

What is real mobility of flagella?

Answer 17

when bacteria move against the flow of liquid.

Question 18

Mobility media, what is plate media?

Answer 18

a semi solid media that is inoculated with bacteria, then incubated for 1-2day to allow growth. - more expensive method

Question 19

Mobility media, what is tube media?

Answer 19

test tube of media is inoculated half way down with bacteria, then incubated for 1-2 days.

Question 20

What is TTC (Triphenyltertrazolium chloride)?

Answer 20

may be added to aid in reading the test tube media test . If growth of bacteria occurs it will change to red color.

Question 21

What are the components of bacterial capsules?

Answer 21

Viscous Layer or Glycocalyx: excreted from some bacteria

Chemical composition: Polysaccharide, polypeptide, or polysaccharide/polypeptide polymer

Capsule: when the glycocalyx is organized and firmly attached to the cell wall.

Slime Layer: when the glycocalyx is unorganized and loosely attached.

Question 22

What are bacterial capsules 3 functions?

Answer 22

1. Phagocytosis
2. Increases bacterial virulence - better able to invade host
3. Protective layer - allows adhering to host surfaces

Question 23

When do you want to use negative stain with capsules?

Answer 23

when the part of the cell you wish to see is unstained.

Question 24

What causes capsule shrinkage?

Answer 24

drying and fixing of slides, as well as heat fixation

Question 25

What do capsules need for development?

Answer 25

Good carbon and energy sources

Question 26

What is the function of a bacteria's cell wall?

Answer 26

it is a rigid wall outside the plasma membrane that protects the plasma membrane and helps keep the shape.

Question 27

What are the components of a bacteria's cell wall?

Answer 27

Peptidoglycan- two alternating sugars joined together by amino acid chains. NAG-NAM chain- sugars from the backbone Tetra-peptide side chains- attach to NAM Peptide cross bridges- 1-5 amino acids hat bond to tetra-peptideside chains.

Question 28

Describe the gram positive cell wall.

Answer 28

- 30-60 (lots) peptidoglycan layer (thicker than gram negative) - responsible for holding the crystal violet of gram stain. - positive gram cells remain blue-black color after gram staining.

Question 29

Describe the gram negative cell wall.

Answer 29

- outer phospholipid/liposaccaride layer - lipoprotein links the outer layer with peptidoglycan (thin layer 7nm) - Gram negative cell wall: Outer lipid layer prevents crystal violet from being retained or penetrating cell wall - gram negative are red/pink because of the counterstain/`

Question 30

What do antibiotics do to the bacterial cell wall?

Answer 30

The break down the peptidoglycan bonds. Eg. penicillin | -Gram positive are more susceptible to this because they have more peptidoglycan.

Question 31

What is protoplast and spheroplast?

Answer 31

P- gram POSITIVE that has lost its cell wall. | S- gram NEGATIVE is lysed but there is still some of the outer membrane attached.

Question 32

What is a hypotonic, hypersonic and isotonic solution?

Answer 32

Hypotonic solution: water moves into cell causing rupture or lysis, lower water concentration/higher salt concentration inside cell than outside Hypertonic solution: water leaves cell causing shrinkage, higher water concentration in cell than outside Isotonic solution: 0.85% saline (NaCl), same concentration as bacterial cells, no water movement

Question 33

What are 4 things that fixation accomplishes?

Answer 33

1. Fixes/sticks bacteria to slide 2. Kills vegetative cells but not spores 3. Makes cells more permeable to stain 4. Prevents autolysis or changes in cells

Question 34

What is the process of fixation?

Answer 34

- Air dry or warm slide completely after applying specimen - Fix slide with bunsen burner(heat) or alcohol for one minute. - Pour alcohol off and let slide air dry again before staining

Question 35

Explain the gram staining procedure. (C.I.A.S.)

Answer 35

“C” Step 1: flood fixed slide with crystal violet for 1 minute, wash with water. All cells & bacteria are blue-purple. “I” Step 2: flood slide with iodine for 1 min.– mordanting effect to fix dye into cells and bacteria. All cells & bacteria are purple-blue-black. "A" Step 3: Decolorize with organic solvents such are ethanol, acetone-alcohol until no more blue comes off slide, wash slide immediately. ****Most important step**** Result should be that gram POSITIVE cells are not decolorized and are still purple-blue & gram NEGATIVE cells are decolorized and are colourless. "S" Step 4: Counterstain with safranin for 1 minute and wash off. Result: negative = pink/red & positive = purple/blue black

Question 36

What happens when over decolorization occurs?

Answer 36

Left on too long. - Gram positives appear gram negative, too much crystal violet has been taken out of bacterial cells - Gram negative bacteria, cells and debris will be still stain red

Question 37

What happens when under decolorization occurs?

Answer 37

Not on long enough - Gram negative bacteria and cells appear gram positive, not enough crystal violet has been removed from bacterial cells - Gram positive bacteria are still stained blue

Question 38

What are the function of plasmids?

Answer 38

1. Resistance to antibiotics 2. Transfer of resistance factors 3. Decomposition of organics 4. Production of toxins 5. Mating and exchange of genetic info

Question 39

Describe fimbriae and pili.

Answer 39

Fimbriae: Non-flagellar, hair-like projections on gram positive and negative cells. They adherence to surfaces and cells, important virulence factor. Pili: Longer than fimbriae, “sex pili”, transfer of genetic material between bacterial cells

Question 40

What are the components of the bacterial cytoplasm?

Answer 40

- 80% water - Ribosomes: 50S and 30S subunits = 70S ribosomes for protein synthesis - Volutin granules: phosphate for ATP - Polysaccharide granules: glycogen, starch - Lipids - Sulfur granules: energy reserve

Question 41

Which bacteria are the only ones that can produced spores?

Answer 41

Gram positive rods.