2.1

Question 1

Why is microbial structure important?

Answer 1

• virulence mechanisms: bacteria control the expression of any molecule that contributes to an organism’s virulence
• must understand how the organism functions to understand disease
• understand what to target on the cell to develop new medication

Question 2

What makes up the cell envelope?

Answer 2

1. cell membrane (inner)
2. cell wall (middle)
3. glycocalyx (outer)

Question 3

What are the cell characteristics of the cell envelope?

Answer 3

• partially responsible for structure and shape
• toxic & immunological properties
• some signs & symptoms

Question 4

Functions of the cell envelope?

Answer 4

protection
- from osmotic balances
- from elimination & infection
- from chemotherapeutic drugs
metabolic
- enzymatic activities
- location of transport proteins
- origin of many signal transduction pathways
- attachments & colonization of environmental surfaces

Question 5

shape of coccus?

Answer 5

spherical shaped

Question 6

shape of coccobacillus?

Answer 6

spherical & rod-shaped (oval)

Question 7

shape of bacillus?

Answer 7

rod shaped

Question 8

shape of vibrio?

Answer 8

curved-rod shaped, comma shape

Question 9

shape of spirilium and spirochete?

Answer 9

spiral shaped

Question 10

diplo-?

Answer 10

two

Question 11

tetrad?

Answer 11

four

Question 12

sarcinae?

Answer 12

cuboidal

Question 13

strepto?

Answer 13

chain

Question 14

staphylo?

Answer 14

clusters

Question 15

Which part of the cell membrane controls fluidity of bilayer similar to cholesterol?

Answer 15

hopanoid

Question 16

What does the cell membrane do?

Answer 16

keeps things in and/or out despite chemical gradients and osmotic pressure

Question 17

What are the three important cell membrane functions?

Answer 17

1. fast cell division
2. proteins for response and reaction
3. transportation of materials

Question 18

What happens during prokaryotic cell division?

Answer 18

FtsZ assembles at site of septum formation; analogous to actin ring for cytokinesis, and separates the two daughter cells and establishes cell polarity

Question 19

How are proteins involved in response and reaction?

Answer 19

• membrane receptors initiate a response to stimuli
  ex. chemotaxis and phototaxis
• membranes are crucial for the electron transport chain, similar to the mitochondria in eukaryotes
• photosynthetic microbes’ cell membrane can perform photosynthesis, similar to chloroplasts in plants
  ex. purple bacteria
• carboxysome: shell surrounding containing Rubisco for carbon fixation (photosynthesis)

Question 20

What is the endosymbiosis theory?

Answer 20

complex eukaryotes are a result of symbiotic combinations of prokaryotic cells
- mitochondria
- chloroplasts

Question 21

What is involved in the transportation of materials?

Answer 21

passive transport
- high to low
- simple diffusion
- channel-mediated
- carrier mediated
active transport
- low to high (use energy)
- ATP, light, or ion gradient

Question 22

What is a proton motive force?

Answer 22

active transport
simple transport: driven by the energy in the proton motive force
- bacteria can utilize the energy of moving protons with the gradient to transport molecules against the gradient
- similar to ATP synthase
ex. multidrug-resistant efflux pumps belong to RND family; tuberculosis

Question 23

What is group translocation?

Answer 23

active transport
chemical modification of the transport substance driven by phosphoenolpyruvate (PEP) to transport against a concentration gradient

Question 24

What are ATP-binding cassette (ABC) transporters?

Answer 24

active transport
uses energy from ATP to move a molecule
periplasmic binding proteins are involved
can use transports to move things out of the cell such as toxins and virulence factors

Question 25

what is the type I secretion system?

Answer 25

used to secrete factors such as toxins and virulence outside of the cell - ABC transporters ex. E. coli, vibrio cholera, and bordetella pertussis

Question 26

Functions of cell wall?

Answer 26

- provides structure and stability for the cell - provides points of attachment (colonization) and receptors for viruses (bacteriophage) - some signs and symptoms - target for antibiotics/chemotherapeutic agents - important for classification

Question 27

Characteristics of gram-positive cell wall?

Answer 27

Stains purple Two layers - thick peptidoglycan (outer) 1. glycan backbone - NAG---NAM (B-1,4 glycosidic linkage) - 80% NAM 2. side chain (tetrapeptide chains) - Side chain comes off NAM - Order: L-alanine, D-glutamic, L-lysine, & D-alanine (some may have 5th D-alanine) 3. inter bridge (cross-link) - pentaglycine inter bridge between L-lysine & D-alanine - cell membrane (inner)

Question 28

Characteristics of a gram-negative cell wall?

Answer 28

stains pink Three layers - outer membrane (outer) - thin peptidoglycan (middle) 1. glycan backbone - NAG---NAM (B-1,4 glycosidic linkage) - 30-40% NAM 2. side chain (tetrapeptide chains) - side-chain comes off NAM - Order: L-alanine, D-glutamic acid, Diaminopimelic acid, D-alanine (some may have 5th D-alanine) 3. inter bridge (cross-link) - direct linkage between D-alanine and diaminopimelic acid - cell membrane (inner)

Question 29

What do gram-positive microbes have in their peptidoglycan and the function?

Answer 29

teichoic acid - structural function - important in cell growth (has to be broken) - important for cell adherence - anchors cell wall into membrane

Question 30

What are bacterial porins?

Answer 30

Transport molecules through outer membrane into periplasmic space; limited selectivity

Question 31

What is unique to gram-negative microbes cell wall?

Answer 31

Lipopolysaccharide (LPS) - Repeating O antigen - core polysaccharide - Lipid A embedded into bilayer, bacterial endotoxin

Question 32

What are the microbes with no repeating O antigen called?

Answer 32

Lipooligosaccharide - Neisseria spp. - Haemophilus spp.

Question 33

What can endotoxin toxicity lead to?

Answer 33

Sepsis - SIRS: severe inflammatory response syndrome - Sepsis: 2 SIRS, confirmed infection - Severe sepsis: sepsis + signs of organ damage - Shock: persistent signs of organ damage

Question 34

What are acid-fast cell walls?

Answer 34

mycobacteria - named due to acid used during staining - contains lipids - mycolic acid (60-90 carbon chains) ex. mycobacterium & nocardia spp.

Question 35

What are the cell "wall-less" microbes?

Answer 35

mycoplasma spp. - m. pnuemoniae - m. hominis Ureaplasma spp. - u. urealyticum

Question 36

What are microbes called when they lose their cell wall?

Answer 36

L-Forms of bacteria - protoplasts: gram + - spheroplasts: gram -

Question 37

What are S layer proteins?

Answer 37

repeated proteins found on the exterior of some bacterial cell walls - increases structural integrity - involved in attachment & protection

Question 38

What is the purpose of the glycocalyx?

Answer 38

material surrounding the cell, often a thick stick sugar coat Two types - slime layer: temporary & less consistent - capsule: permanent & organized - protection - adherence - biofilms connect their glycocalyx ex. streptococcus mutans (dental plaque) - classification - carbohydrate reserves?