8/3/2019 CE114HW3Sp12

1/2

Civil and Envirnmental Engineering 114 Assignment #3

ENVIRONMENTAL MICROBIOLOGY Spring 2012

Due: Thur. Feb. 9

Required Reading: Brock, remaining Chap. 3, start on Chapters 4.0-4.1, 4.4-4.7, appendix

1 and bSpace handout on energy.

1. Calculate the surface-to-volume ratio of the following cells. Explain the consequences

of these differences in surface-to-volume ratio for cell function.

D = diameter

L = length

Coccoid Cell:

V = 4/3*pi*(D/2)^3

A = 4*pi*(D/2)^2

A:V= 6/D

Rod Cell:

V = 4/3*pi*(D/2)^3 + pi*(D/2)^2*L

A = 4*pi*(D/2)^2 + 2*pi*D*L

V m3 A m2 A/V

a. coccoid cell, 1

m diameter

pi/6 pi 6

b. coccoid cell, 20

m diameter

4000pi/3 400pi 0.3

c. bacillus (rod)

cell, 1 m

diameter/4 m

length

7pi/6 9pi 7.71

d. bacillus (rod)

cell, 2 m diameter/

15 m length

49pi/3 64pi 3.92

2. Answer Brock Review Question 4 in Chapter 3.

Question: Describe a major chemical difference between membranes ofBacteria and

Archaea (section 3.3).

3. Answer Brock Review Question 6 in Chapter 3.

Question: Cells ofEsherichia coli take up lactose via lac permease, glucose via the

phosphotransferase system, and maltose via an ABC-transporter. For each of these

sugars describe: (1) the components of their transport system and (2) the source of

energy that drives the transport event (Section 3.5).

4. Answer Brock Review Question 8 in Chapter 3.

Question: List several functions of the outer membrane in gram-negativeBacteria.

What is the chemical composition of the outer membrane (Section 3.7)

5. Answer Brock Review Question 9 in Chapter 3.

8/3/2019 CE114HW3Sp12

2/2

Question: What cell wall polysaccharide common inBacteria is absent fromArchaea?

What is unusual about S-layers compared to other cell walls of prokaryotes? What

types of cell walls are found inArchaea (Section 3.8)?

6. Describe the structure and function of a bacterial pilus. How does it differ from a

fibriae?

7. Answer Brock Review Question 11 in Chapter 3.

Question:What types of cytoplasmic inclusions are formed by

prokaryotes? How does an inclusion of poly-B-hydroxybutyric aciddiffer from a magnetosome in composition and metabolic role(Section 3.10)?

8. Answer Brock Review Question 12 in Chapter 3.

Question:What is the function of gas vesicles? How are these

structures made such that they can remain gas tight (Section 3.11)?

9. Answer Brock Review Question 13 in Chapter 3.

Quesiton:In a few sentences, indicate how the bacterial endospore

differs from vegetative cell in structure, chemical composition, andability to resist extreme environmental conditions (Section 3.12)?

10. Answer Brock Review Question 15 in Chapter 3.

Question: Describe the structure and function of a bacterialflagellum. What is the energy source for the flagellum? How do theflagella ofBacteria differ from those ofArchaea in both size and

composition (Section 3.13)?

11. Answer Brock Review Question 17 in Chapter 3.

Question: In a few sentences, explain how a motile bacterium is able to sense the

direction of an attractant and move toward it (Section 3.15).

12. Answer Brock Application Question 3 in Chapter 3.

Question: Calculate the amount of time it would take a cell of Escherichia coli (1 2

m) swimming at maximum speed (60 cell lengths per second) to travel all the way

up a 3-cm-long capillary tube containing a chemical attractant.