Lecture 2 Study Questions

Question 1

List the main differences between prokaryotic and eukaryotic cells.

Answer 1

Prokaryotic cells: bacterial and archaeal cells, smaller, no nuclear membrane or nucleus, no membrane structures and have a complex cell wall containing peptidoglycans
Eukaryotic cells: animal, plant, fungal, algae and protozoan cells, larger, have nuclear membrane and nucleus, have membrane structures, only plants, algae and fungi have simple cell walls (animals and Protozoa don’t)

Question 2

Describe the function and/or types of

a) glycocalyx, b) flagella, c) pili and fimbriae

Answer 2

A) Glycocalyx: a gelatinous material which coats the surface of some bacteria. Has two types: capsules (highly organised) & slime (not highly organised)
B) Flagella: motility only
C) pili: long projections, adherence and conjugation
D) fimbrae: short projections, adherence only.

Question 3

What is the main difference between gram positive and gram negative bacteria?

Answer 3

Gram pos have a large amount of peptidoglycan in cell wall- stain purple
Gram neg have a small amount of peptidoglycan in cell wall- stain pink

Question 4

List the steps of a gram stain. List the colour of both a GPOS and GNEG at the end of each step.

Answer 4

1. Fixation: heat fix smear on slide
   - -G. pos & G. Neg colourless
2. Crystal violet: 30 secs, stains all bacteria
   - -G. pos & G. neg: dark blue/ purple
3. Iodine treatment: 30 secs, fixes stain
   - -G. Pos & G. neg: lighter purple
4. Decolorisation: alcohol or acetone (15 secs/ 1 sec), decolourises
   - -G. Pos: purple, G. Neg; colourless
5. Counter stain/ safranin: Carbon fuchsin, 30 secs
   - - G. Pos: purple, G. Neg: pink

Question 5

How do bacteria reproduce and list the 4 growth phases in a broth culture?

Answer 5

A) asexual reproduction called binary fission

B) initial lag phase, exponential phase, stationary phase, death or decline phase

Question 6

What are: mesophiles, psychrophiles, obligate anaerobes, facultative anaerobes and carboxyphiles?

Answer 6

A) mesophiles: bacteria that grow in 10-45C temp (optimum= 37C (body temp))
B) psychrophiles: bacteria that grow in 0- <20C temp (optimum= 15C)
C) obligate anaerobes: bacteria that are unable to grow in the presence of oxygen.
D) facultative anaerobes: able to grow with or w/o oxygen
E) carboxyphiles: grow best in increased conc of CO2 (2.5-5-10%)

Question 7

Briefly describe bacterial respiration and fermentation.

Answer 7

bacterial respiration (uses oxygen):
-includes obligate aerobes & facultative microbes.
-produces lots of ATP & CO2 and H2O via kerbs cycle & ETC.
Bacterial fermentation (no oxygen):
-includes obligate anaerobes
-produces low ATP & organic wastes such as acids & alcohols.

Question 8

Describe glycolysis: what is the starting carbohydrate; what is the storage molecule produced; and
what is the end product? How many nett energy molecules are produced from 1 carbohydrate
molecule during glycolosis?

Answer 8

• Glycolysis is an anaerobic process (no oxygen) that includes all microbes.
• It’s starting carbohydrate is glucose
• the storage molecule produced is ATP
• the end products are 2 molecules of pyruvic acid.
• 2 net energy molecules are produced

Question 9

Describe the terms: catabolism, anabolism, oxidation, reduction, and enzymes.

Answer 9

• Catabolism (decomposition): Breaking of chemical bonds, larger molecules broken into smaller molecules and energy is released (exergonic)
• Anabolism (biosynthesis): Creation of chemical bonds to form larger molecules from smaller molecules, requires energy (endergonic).
• Oxidation- electron(s) loss, Reduction- electron(s) gain
• enzymes are biological molecules that act as catalysts for metabolic reactions, they greatly increase rate of reactions but are not consumed in reactions.