Chapter Two

Question 1

Cell envelope:

Answer 1

Structure that surrounds the cytoplasm of prokaryotes.
Cell membrane, Cell wall, Appendages attach/integral to envelope

Question 2

Monomorphic:

Answer 2

Single-shaped, most bacteria are monomorphic.
ex.) antibiotic-resistant Staphylococcus aureus

Question 3

Pleomorphic:

Answer 3

Many shapes, a few bacteria are pleomorphic.
ex.) Helicobacter pylori

Question 4

Peptidoglycan:

Answer 4

Peptidoglycan is a rigid envelope surrounding the cytoplasmic membrane of most bacterial species.
Major component of the cell wall in bacteria.

It helps protect bacterial cells from environmental stress and helps preserve cell morphology throughout their life cycle. Peptidoglycan biosynthesis is also an important regulator of bacterial cell division.

Question 5

Murein and its composition:

Answer 5

Unique to bacteria, a target for antibiotics.
ex.) B-lactams (Penicillin) inhibit synthesis.

Lipopolysaccharides, sugar part is made of N-acetylglucosamine and N-acetylmuramic acid units

Question 6

Periplasm:

Answer 6

Aqueous space between the inner and outer membrane.
Secreted proteins (like B-lactamase and other enzymes).

Question 7

What are the things that protect the cell membrane?

Answer 7

Gram-positive, gram-negative, acid-fast, mycoplasma (none).

Question 8

Gram-positives:

Answer 8

Thick cell wall (thick peptidoglycan)
Teichoic acid and Lipoteichoic acid.

Question 9

What are teichoic acids (Gram-positive Cells)?

Answer 9

– Lipoteichoic acid links to the plasma membrane
– Wall teichoic acid links to peptidoglycan
- May regulate movement of cations
- Provide antigenic variation
- Pathogenesis- Adherence
- Rigidity

Question 10

Gram-negatives:

Answer 10

Thin cell wall, out membrane with LPS (hydrophilic)- hydrophobic barrier.
Periplasm, LPS and endotoxin, porin.

Question 11

Gram-negative cell wall:

Answer 11

Outer membrane is chemically distinct from all other biological membranes, resistant to harmful chemicals, inner part regular phospholipids, outer part has Lipopolysaccharides (LPS), Lipid A is an endotoxin.

• Outer membrane makes the cell wall less permeable.
• Porins permit the diffusion of hydrophilic compounds.
• Transport systems – special proteins for
  larger hydrophilic compounds.
• Periplasm: Aqueous space between the
  inner and outer membrane
• Contains murein and gel-like solution of cell wall precursors and proteins that assist in nutrition
• Concentrate valuable enzymes

Question 12

Periplasm:

Answer 12

In gram-negatives, the aqueous space between the inner and outer membrane.

Question 13

Acid-fast cells:

Answer 13

Waxes (mycolic acids- branched hydrocarbons, 60-90 carbons long).

Question 14

Archaea cell walls:

Answer 14

Many have no cell wall, they have an S-layer, which are glycoproteins. They have a special cell membrane: isoprenoid-containing, bilayer, long monolayer.

Question 15

Shape of prokaryotic cells
Bacillus:
Coccus:
Spiral:

Answer 15

Bacillus: rod-shaped
Coccus: spherical-shaped
Spiral: vibrio, spirillum, spirochete

Question 16

Arrangement of prokaryotic cells
Pairs:
Clusters:
Chains:
Groups of four:
Cubelike groups of eight:

Answer 16

Pairs: diplococci, diplobacilli
Clusters: staphylococci
Chains: streptococci, streptobacilli
Groups of four: tetrads
Cubelike groups of eight: sarcinae

Question 17

Shapes and arrangements of bacterial cells:

Answer 17

Question 18

Morphology’s link to properties of prokaryotic cells:

Answer 18

typically does not predict
physiology, ecology, phylogeny, or other
properties of a prokaryotic cell.

Question 19

Selective forces involved in setting the morphology:

Answer 19

• Optimization for nutrient uptake (small cells and high surface-to-volume ratio, like appendaged cells).
• Swimming motility in viscous environments or near surfaces (helical or spiral-shaped cells).
• Gliding motility (filamentous bacteria).

Question 20

What are the units used when visualizing prokaryotic cells?

Answer 20

Measured using the metric system
1 micrometer (µm) = 10^-6 m
1 nanometer (nm) = 10^-9 m

Question 21

Microscopy resolution:

Answer 21

The ability of the lenses to distinguish fine detail and structure.
White light- Resolution: 0.2 µm
Shorter wavelengths of light provide greater resolution.
A microscope with a resolving power of 0.2μm can distinguish between two points ≥ 0.2 μm apart.

Question 22

Microscopy refractive index:

Answer 22

Measures the light-bending ability of a medium.
Specimen’s refractive index must be different from the medium.

Question 23

What are the four types of microscopy and when would each be used? What resolution is used for each?

Answer 23

Light microscopy: Uses light to observe specimens. Stains, fluorescent stains. Uses 0.2 microns resolution.

Electron microscopy (TEM and SEM resolution):
TEM: extremely high resolving power, visualize internal structures of the cell, 10,000–10,000,000X; resolution 0.01 nm
SEM: Less resolving power than TEM, but examines intact surfaces. 1,000–500,000X; resolution 10 nm

Scanning Probe Microscopy: Studying surfaces at the nanoscale level.

Question 24

What is the Compound Light Microscope used for in Brightfield microscopy, and describe the parts (11 parts).

Answer 24

Question 25

What is the structure and function of the prokaryotic cell membrane?

Answer 25

Selective barrier, all cells have a cell membrane, The membrane consists of a phospholipid bilayer, 200+ proteins, some have sterols or sterol-like molecules, but many don’t.

Question 26

Differences between archaeal and bacterial cell membranes/cell membrane lipids

Answer 26

Question 27

Cell membrane structure and function:

Answer 27

Busy places, osmotic and solute barriers, establishment of an ion gradient (production of motive force and ATP generation), some have photosynthesis.

Question 28

What are the four structure types that protect the cell membrane and what separates them?

Answer 28

Gram-positive, gram-negative, acid-fast, mycoplasma (none).

Gram-positive bacteria have a thick peptidoglycan layer and no outer lipid membrane whilst Gram-negative bacteria have a thin peptidoglycan layer and an outer lipid membrane. Acid-fast bacteria are gram-positive, but in addition to peptidoglycan, the outer membrane or envelope of the acid-fast cell wall of contains large amounts of glycolipids

Question 29

Gram-stain mechanism:

Answer 29

• Crystal violet-iodine crystals form in the cell
  Gram-positive:
• Alcohol dehydrates peptidoglycan
• CV-I crystals do not leave.
  Gram-negative:
• Alcohol dissolves the outer membrane and leaves holes in peptidoglycan
• CV-I washes out.

Question 30

Special properties of gram-positive vs. gram-negative cells:

Answer 30

Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives

Question 31

Structure and function of archaeal cell wall:

Answer 31

Many do not have a cell wall. They have S-layers (glycoproteins). Have a special cell membrane (isoprenoid containing, bilayer, long monolayer). Psuedomuerin.

Question 32

Psuedomuerin in Archaea cell wall:

Answer 32

Different from meurin by linkage of sugar backbone and type of amino acids (L instead of D).

Question 33

Extracellular Structures:

Answer 33

Capsules and slime layers- different in degree of attachment, adherence and protection.
Pili- attachment, transfer of substrate, straight proteins, usually smaller than flagella.
Flagella- usually involved in movement.
Axial filaments- movement.

Question 34

Capsules, Slime Layers, and Exopolysaccarides:
*What they do, where they are

Answer 34

Outside the cell wall.
Capsule: well attached and uniform
Slime layer: loose
Exopolysaccaride (EPS): usually viscous, sticky, and gelatinous polymer, composed of polysaccharide, polypeptide, or both.

Retain water and nutrients
Prevent phagocytosis
Protection from chemicals (antibiotics or bactericides)
Communication
Attachment
Biofilm formation

Question 35

Flagella:

Answer 35

Embedded in the cell wall/plasma membrane
Bacterial Motility:
1. Filament with chains of flagellin protein
2. Attached to a hook
3. Anchored to the wall and membrane by the basal body

Question 36

Types/Arrangements of flagella:

Answer 36

Question 37

What is running and tumbling in flagella?

Answer 37

Rotate flagella to run: move in one direction for a length of time.
Tumble: abrupt changes, random changes in direction caused by reversal of flagellar movement.
Taxis: move toward or away from stimuli
Flagella proteins are H antigens useful for distinguishing among serovars

Question 38

Axial Filaments (endoflagella):

Answer 38

In spirochetes, anchored at one end of a cell and spirals around the cell. Rotation causes cell to move.

Question 39

Pili:

Answer 39

Pili (aka fimbriae):
* Nearly all Gram-Negative
* Hairlike appendages that are shorter, straighter, and
thinner than flagella
* Used for attachment, transfer of DNA, motility, antigen