1.2 unit test

Question 1

Gram positive bacteria

Answer 1

• Stains purple (absorbs dye)
• Thick layers of peptidoglycan
• Lacks outer membrane

Question 2

Gram negative bacteria

Answer 2

• Stains pink (doesn’t retain dye)
• Thinner peptidoglycan layers
• Outer membrane that protects it from antibiotic penetration

Question 3

Types of antibiotics

Answer 3

Penicillins (beta-lactams)
Tetracyclines
Fluoroquinolones
Sulfonamids

Question 4

Penicillins (beta-lactams) function

Answer 4

Inhibit peptidoglycan production (occurs in the call wall) -> inner membrane bursts due to osmotic pressure

Question 5

Efflux

Answer 5

Antibiotics enter through porin, but an efflux pump continuously pumps out the antibiotics so there is not a high enough concentration to cause cellular damage

Question 6

E. Coli I

Answer 6

Streptomycin-resistant
Chromosomal DNA

Question 7

E. Coli II

Answer 7

Ampicillin-resistant
Plasmid DNA

Question 8

Diseases caused by more antibiotic-resistant bacteria

Answer 8

Tuberculosis, gonorrhea, malaria, skin/ear infections, pneumonia

Question 9

Flagella

Answer 9

Help cells move (motility) - can be one or multiple flagella

Question 10

Pilli

Answer 10

Short, hair-like structures found on bacteria that help them adhere to surfaces/other cells and DNA transfer

Question 11

Tetracyclines function

Answer 11

Inhibit DNA translation by preventing tRNAs from binding to ribosomes
(occurs in cytoplasmic ribosomes)

Question 12

Fluoroquinolones function

Answer 12

• Inhibit DNA replication
• Occurs in nucleoid region
• Prevents topoisomerases (gyrases) from functioning in replication

Question 13

Sulfonamids function

Answer 13

• Inhibit folic acid synthesis
• Occurs in mitochondria
• Bacteria aren’t killed, but they can’t multiply

Question 14

Lab steps (days 1, 2, 3)

Answer 14

End of day 1:
- LB agar plate (no antibiotics): both strains grew on their respective sides
- LB/strep plate: only E. Coli I grew because it had strep resistance
- LB/amp plate: only E. Coli II grew
- LB/amp/strep: no growth

Day 2:
- Combined E. Coli I from strep plate + E. Coli II from amp plate (mixed the strains on the mix plate)
- End of day 2: the mix plate did not contain antibiotics, so E. Coli I & II grew (plus the new strain - E. Coli IA)

Day 3:
- Transferred bacteria from mix plate onto 3 plates- just strep, just amp, & both strep and amp
- Bacteria grew on all 3 plates since the IA strain had amp & strep resistance

Question 15

G+ cell structure (outer->inner)

Answer 15

Capsule (thinner)
Cell wall
Cell membrane
Cytoplasm
Nucleoid

Question 16

G- cell structure (outer->inner)

Answer 16

Capsule (thicker)
Outer membrane (unique to G- and contains endotoxins)
Cell wall
Cell membrane
Cytoplasm
Nucleoid